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Generac GT-990 Engine

The Generac GT-990 is a 992 L 2-cylinder air-cooled engine rated at 3600 rpm, producing up to 18.6 kW. It powers generator sets from Generac and Power Systems, including the 8.1 GN, Model 004666 and Model 005011. It holds 1.5 L (0.4 gal) of oil.

Also known as: Generac GT-990, GT-990

Part of the Generac GT990 engine family — 2 variants share parts & fitment.

992.0 L

Displacement

Cylinders

3600 rpm

Rated speed

18 kW

Gross power

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Oil capacity	1.5 L
Displacement	992.0 L
Cylinders	2
Aspiration	Air-cooled
Rated speed	3600 rpm
Gross power	18 kW

Generator sets powered by this engine

Shared across brands: Generac, Power Systems

Generac 8.1 GNGenerac Model 004666Generac Model 005011Power Systems GT-990

How to read your Generac engine serial & model number →

Troubleshooting

Symptoms & remedies

Symptom	Remedy
Generator Produces Zero Voltage or Residual Voltage	TEST 4 - PERFORM FIXED EXCITATION / ROTOR AMP DRAW PERFORM STATOR INSULATION RESISTANCE TEST - SECTION 1.4 PERFORM ROTOR INSULATION RESISTANCE TEST - SECTION 1.4 TEST 7 - TEST STATOR TEST 5 - WIRE CONTINUITY TEST 6 - FIELD BOOST TEST 8 - CHECK ROTOR CIRCUIT REPAIR OR REPLACE FUSES
Generator Produces Low Voltage at No-Load	TEST 11 - CHECK AC OUTPUT FREQUENCY TEST 12 - ADJUST ENGINE GOVERNOR TEST 12A - CHECK STEPPER MOTOR CONTROL TEST 2 - CHECK AC OUTPUT VOLTAGE TEST 13- ADJUST VOLTAGE REGULATOR
Generator Produces High Voltage at No-Load	REPLACE DEFECTIVE VOLTAGE REGULATOR
Voltage and Frequency Drop Excessively When Loads are Applied	TEST 14 - CHECK VOLTAGE AND FREQUENCY UNDER LOAD TEST 79 - CHECK IDLE CONTROL TRANSFORMER TEST 80 - CHECK LC1 & LC2 WIRING TEST 81 - CHECK IDLE CONTROL TRANSFORMER PRIMARY WIRING TEST 15 - CHECK FOR OVERLOAD CONDITION TEST 12 - CHECK AND ADJUST ENGINE GOVERNOR

Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.

Common problems

The engine will not crank.
Cause: 1. Fuse blown 2. Loose, corroded or defective battery cables 3. Defective starter contactor 4. Defective starter motor
Fix: 1. Replace fuse. 2. Tighten, clean or replace as necessary. 3. * 4. *
The engine cranks but will not start.
Cause: 1. Out of fuel 2. Defective fuel solenoid (FS) 3. Open #14 wire from engine control board 4. Defective spark plug(s)
Fix: 1. Replenish fuel. 2. * 3. * 4. Clean, re-gap or replace plug(s).
The engine starts hard and runs rough.
Cause: 1. Air cleaner plugged or damaged 2. Defective spark plug(s) 3. Fuel regulator not set. 4. Fuel pressure incorrect
Fix: 1. Check, replace air cleaner. 2. Clean, re-gap or replace plug(s). 3. Set fuel regulator. 4. Confirm fuel pressure to regulator is 10-12” water column (0.36-0.43 psi) for LP, and 5-7” water colum (0.18-0.25 psi) for natural gas.
The AUTO/OFF/MANUAL switch is set to OFF, but the engine continues to run.
Cause: 1. Defective switch 2. AUTO/OFF/MANUAL switch wired incorrectly 3. Defective control board
Fix: 1. * 2. * 3. *
Voltage and Frequency Drop Excessively When Loads Are Applied
Fix: TEST 14 - CHECK VOLTAGE AND FREQUENCY UNDER LOAD, BOTH LOW -> TEST 15 - CHECK FOR OVERLOAD CONDITION, NOT OVERLOADED -> GOOD -> IF RECONFIGURED TO LP GAS, VERIFY THAT PROPER PROCEDURE WAS FOLLOWED (REFER TO INSTALLATION MANUAL), GOOD -> OVERLOADED -> DISCONTINUE TESTING, REDUCE LOADS TO UNIT’S RATED CAPACITY, TEST 12 - CHECK STEPPER MOTOR CONTROL, GOOD -> BAD -> REPAIR OR REPLACE, LOOK FOR A SHORTED CONDITION IN A CONNECTED LOAD OR IN ONE OF THE LOAD CIRCUITS, GOOD -> TEST 7 - CHECK STATOR AC POWER WINDINGS, ENGINE CONDITION GOOD -> REPAIR OR REPLACE, BAD -> TEST 16 - CHECK ENGINE CONDITION, GOOD -> GO TO “PROBLEM 18 - ENGINE STARTS HARD AND RUNS ROUGH/LACKS POWER” SECTION 4.3
Unit consumes large amounts of oil.
Cause: Break-in procedure not followed (see Section 2.1)
Fix: *Contact the nearest Authorized Dealer for assistance.
Unit consumes large amounts of oil 807
Fix: Adjust oil to proper level. See 'Engine Oil Recommendations'. Check for oil leaks.
There is no transfer to standby after utility source failure.
Cause: 1. Defective transfer switch coil 2. Defective transfer relay 3. Transfer relay circuit open 4. Defective control logic board
Fix: 1. * 2. * 3. * 4. *
There is no AC output from the generator.
Cause: 1. Main line circuit breaker open 2. Generator internal failure
Fix: 1. Reset circuit breaker to ON (or closed). 2. *
Engine will not crank 801
Fix: Correct short circuit condition, replace 7.5A fuse in generator control panel. Tighten, clean or replace battery cables as necessary. Replace defective starter contactor or motor.
Engine starts hard and runs rough 803
Fix: Check, replace air cleaner as necessary. Clean, re-gap or replace spark plugs as necessary. Confirm fuel pressure to regulator is 10-12” water column (0.36-0.43 psi) for LP, and 5-7” water column (0.18-0.25 psi) for natural gas. Move selector to correct position. Verify choke plate moves freely.
Engine cranks but will not start 802
Fix: Replenish fuel/Turn on fuel valve. Replace defective fuel solenoid or open #14 wire from engine control board. Clean, re-gap or replace spark plugs as necessary. Reset valve lash. Verify choke plate moves freely.
Wiring Error ALARM 2099
Utility failure 0
Fix: Crank and start engine, transfer load to Generator if Utility returns above 75% nominal for 15 seconds
Unstable Voltage or Incorrect Output Which is Not Triggering a Shutdown
Fix: TEST 1 - CHECK AC OUTPUT VOLTAGE, ERRATIC -> PROCEED TO PROBLEM 3

Compiled from service & troubleshooting documentation across every generator set that uses the Generac GT-990.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			0C8127		Amazon eBay $15.99 NAPA $24.03 FridayParts $21.87
Fuel filter	Generac OE		924-0371	50 hr	Amazon eBay
Oil filter			70185		Amazon eBay $18.99 NAPA $9.09 KuduParts $11.00
Battery	12V, 75Ah		924-0380	600 hr	Amazon eBay
Belt			924-0365	1000 hr	Amazon eBay
Coolant	Generac OE		924-0370	1000 hr	Amazon eBay
Oil	Change the engine oil.	4.31 L	—	150 hr
Spark plug			—	1000 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Engine oil level	Check	8 hr		Check before each use / at least every 8 hours
Oil and oil filter	Change	8 hr		First service — First 8 hours of operation
Oil level	Check	24 hr	1 mo	Monthly or every 24 hours of continuous operation
Aceite del motor	Change	25 hr		First service — Después del período de asentamiento de 25 horas, se recomienda utilizar el aceite 5W-20 propiedad de Generac para uso continuo.
Engine oil	Change	25 hr		First service — After the 25 hour break-in period, use Generac 5W-20 GEO for continuous use
Oil and filter	Change	25 hr		First service — After first 25 hours of operation
Engine governor oil level	Check	50 hr		Check prior to initial use and every 50 operating hours thereafter.
Engine oil and filter	Replace	100 hr	12 mo	First service — After first 25 hours; then every 100 hours or 1 year. Cold weather (<4.4°C) or continuous hot (>29.4°C): every 100 hours or 1 year
Aceite de motor y filtro de aceite	Change	200 hr	24 mo	First service — Programa de mantenimiento A
Batería (condición, nivel de electrolito y estado de carga)	Check	200 hr	24 mo	Programa de mantenimiento A
Battery condition and charge	Check	200 hr	24 mo	Schedule A maintenance
Engine oil and oil filter	Replace	200 hr	24 mo	First service — Schedule A (Every Two Years or 200 Hours) and Schedule B (Every Four Years or 400 Hours). Change engine oil and filter after first 25 hours. In cold weather (below 40 F / 4.4 C) or continuous hot weather (above 85 F / 29.4 C), change every year or 100 hours.
Huile à moteur et filtre à huile	Change	200 hr	24 mo	First service — Calendrier A: tous les deux ans ou toutes les 200 heures. Changer l'huile et le filtre après les 25 premières heures. En conditions froides (moins de 4,4 °C/40 °F) ou fonctionnant en continu à plus de 29,4 °C/85 °F, changer annuellement ou toutes les 100 heures.
Oil	Change	200 hr	24 mo	First service — Every 2 years or 200 hours; change after first 8 hours then every 200 hrs/2 yrs thereafter, more often under heavy load, dust, or high temp
Oil filter	Change	200 hr	24 mo	First service — Every 2 years or 200 hours
Oil filter	Replace	200 hr	24 mo	200 hours or 2 years, whichever occurs first
Óleo lubrificante e filtro de óleo	Change	200 hr	24 mo	First service — Trocar após as primeiras 25 horas; Programação A (2 anos ou 200 h); em clima frio (<4,4 °C) ou quente contínuo (>29,4 °C) anualmente ou 100 h
Aceite del motor y filtro de aceite	Replace	400 hr	48 mo	First service — Programa B: cada cuatro años o 400 horas.
Air cleaner	Clean	400 hr		Clean or replace as necessary; R = Replace as Necessary; 400 hours
Air filter	Replace	400 hr	48 mo	Schedule B maintenance
Bougies d'allumage	Clean	400 hr	48 mo	Nettoyer les bougies, vérifier l'écartement ou les remplacer. Calendrier A et Calendrier B.
Bujía(s)	Replace	400 hr	48 mo	Programa B: cada cuatro años o 400 horas.
Bujías	Replace	400 hr	48 mo	Programa B; limpiar, comprobar separación y sustituir
Engine air filter	Replace	400 hr	48 mo	Schedule B. Emissions-critical.
Engine oil and oil filter	Change	400 hr	48 mo	First service — Schedule B (every four years or 400 hours).
Filtre à air du moteur	Replace	400 hr	48 mo	Calendrier B: tous les quatre ans ou toutes les 400 heures.
Filtro de aire del motor	Replace	400 hr	48 mo	Programa de mantenimiento B
Filtro de ar do motor	Replace	400 hr	48 mo	Programação B (4 anos ou 400 h)
Folga da válvula	Adjust	400 hr	48 mo	First service — Inspecionar/ajustar após as primeiras 25 h e depois a cada 400 h; Programação B; exclui 14/18 kW com motor 816 cc
Jeu des soupapes	Adjust	400 hr		First service — Vérifier et régler après les 25 premières heures de fonctionnement, puis toutes les 400 heures.
Luz de válvulas	Adjust	400 hr	48 mo	First service — Programa B; inspeccionar/ajustar cada 400 horas
Sediment trap	Clean	400 hr	48 mo	Schedule B maintenance
Separación de la válvula	Adjust	400 hr	48 mo	First service — Programa B. Inspeccione y ajuste después de las primeras 25 horas y luego cada 400 horas. No necesario en unidades 14/18 kW con motor 816 cc.
Spark plug(s)	Clean	400 hr		Replace every 4 years or 400 hours
Spark plugs	Replace	400 hr	48 mo	Every Four Years or 400 Hours (Schedule B); clean, check gap, replace
Valve clearance	Adjust	500 hr	48 mo	First service — Schedule B; inspect/adjust valve clearance after first 25 hours of operation, then at 400 hour intervals. Where applicable; excludes units with hydraulic lifters (14 or 18 kW with 816cc engine).
Vela(s) de ignição	Replace	400 hr	48 mo	Programação B (4 anos ou 400 h)
Air cleaner	Inspect	400 hr	24 mo	Yearly (Y); replace as necessary
Air cleaner	Replace	200 hr	24 mo	Yearly (inspect and replace as necessary)
Bateria	Check		12 mo	Estado da bateria; todos os anos

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Valve clearance	0.002 - 0.004 inch (0.05 - 0.1 mm)	inch (mm)	engine cool
Gap	Armature Air Gap	0.008-0.012	inch
Gap	Breaker Point Gap	0.018-0.022	inch
Gap	Folga da vela de ignição	0,020	pol
Gap	Folga da vela de ignição	0,040	pol
Gap	Folga da vela de ignição	0,508	mm
Gap	Folga da vela de ignição	1,02	mm
Gap	Ignition magneto (armature) air gap	0.008-0.012	inch (0.20-0.30 mm)
Gap	Ignition magneto (armature) air gap	0.008-0.012 inch (0.20-0.30mm)	inch	V-twin engines; not adjustable on single cylinder engines
Gap	Ignition magneto air gap	0.008-0.012 inch (0.20-0.30 mm)	gap	V-twin engines; fixed non-adjustable on single cylinder
Gap	Magneto gap between flywheel	0.010	inch
Gap	Separación de electrodos de bujía (11 kW)	0.030	in (0.76 mm)
Gap	Separación de electrodos de bujía (16/20/22 kW)	0.040	in (1.02 mm)
Gap	Separación de electrodos de bujía (9 kW)	0.020	in (0.508 mm)
Gap	Separación de las bujías	0.508	mm (0.020 pulg.)
Gap	Separación de las bujías	1.02	mm (0.040 pulg.)
Gap	Spark Plug Gap	0.020	in (0.508 mm)	9 kW (GH-426)
Gap	Spark Plug Gap	0.030	in (0.76 mm)	11 kW (GTH-530)
Gap	Spark Plug Gap	0.031-0.035	inch
Gap	Spark Plug Gap	0.040	in (1.02 mm)	16/20/22 kW (GT-999)
Gap	Spark plug gap	0.50	mm (0.020 inch)
Gap	Spark plug gap	0.508	mm
Gap	Spark plug gap	0.76	mm (0.030 inch)
Gap	Spark plug gap	0.76 mm (0.030 inch)	gap	410 cc and 530 cc engines
Gap	Spark plug gap	1.02	mm (0.040 inch)
Gap	Spark plug gap	1.02 mm (0.040 inch)	gap	990 cc and 999 cc engines
Gap	Spark plug gap (10 kW)	0.020	in (0.508 mm)
Gap	Spark plug gap (11 kW)	0.030	in (0.76 mm)
Gap	Spark plug gap (12/15 kW)	0.508	mm (0.020 inch)
Gap	Spark plug gap (14-24 kW)	0.040	in (1.02 mm)
Gap	Spark plug gap (16/20/22 kW)	0.040	in (1.02 mm)
Gap	Spark plug gap (410 cc, 7 kW)	0.030	inch
Gap	Spark plug gap (530 cc, 10 kW)	0.030	inch
Gap	Spark plug gap (7 kW)	0.76	mm (0.030 inch)
Gap	Spark plug gap (9 kW)	0.020	in (0.508 mm)
Gap	Spark plug gap (990 cc, 13-16 kW)	0.040	inch
Gap	Écartement des électrodes des bougies d'allumage	0.508	mm (0,020 po)
Gap	Écartement des électrodes des bougies d'allumage	0.76	mm (0,030 po)
Gap	Écartement des électrodes des bougies d'allumage	1.02	mm (0,040 po)
Other	Compression Ratio GH-410	8.6:1
Other	Compression Ratio GT-530	9.5:1
Other	Compression Ratio GT-990	9.5:1
Other	Compression Ratio GT-999	9.5:1
Other	Compression difference between cylinders shall not exceed	25	percent
Other	Compression ratio	8.6:1
Other	Compression ratio	9.5:1
Other	Cylinder leak down acceptable leakage	20	percent	regulated pressure 80 psi
Other	Exercise time length (16-22 kW)	5	minutes
Other	Exercise time length (9-11 kW)	12	minutes
Other	Fusível do painel de controle	7,5	A
Other	Generator output frequency under full rated load	>58	Hertz	full rated load
Other	Generator output under full rated load	>230	volts	full rated load
Other	Good starter motor maximum	62	Amps	starter performance test
Other	Minimum allowable compression pressure, cold engine (single cylinder)	60	psi	cold
Other	Ordem de partida (10 kW)	15 s de arranque, 7 s de repouso, seguidos por quatro ciclos adicionais de 7 s de arranque e 7 s de repouso		cinco ciclos de manivela
Other	Ordem de partida (14 a 24 kW)	16 s de arranque, 7 s de repouso, 16 s de arranque, 7 s de repouso, seguidos por três ciclos adicionais de 7 s de arranque e 7 s de repouso		cinco ciclos de manivela
Other	Perda de potência do motor por altitude	3,5	% a cada 304,8 m (1.000 pés) acima do nível do mar
Other	Perda de potência do motor por temperatura	1	% a cada 6 °C (10 °F) acima de 15 °C (60 °F)
Other	Rated Horsepower @ 3,600 rpm GH-410	14.8	HP
Other	Rated Horsepower @ 3,600 rpm GT-530	18	HP

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Coolant	50 percent soft water and 50 percent ethylene glycol base anti-freeze	low silicate anti-freeze		2.0 U.S. gallons	Do not use chromate base rust inhibitor or high silicate anti-freeze boosters.
Engine oil		API Service Class SJ, SL or better		1.9 Qts	Engine crankcase oil capacity including filter, approximately
Engine oil	10W-30	API Service Class SJ, SL or better			For expected operating temperatures between 40 °F and -10 °F
Engine oil	30 weight organic oil (factory fill)				Units run and tested at factory prior to shipping, no break-in required
Engine oil	5W-20				Aceite 5W-20 propiedad de Generac para uso continuo, después del período de asentamiento de 25 horas.
Engine oil	5W-20 (Generac proprietary)	API Service Class SJ, SL, or better		1.03 L	Oil capacity including filter. Use for continuous use after the 25 hour break-in period; specifically formulated for gaseous powered Generac generators. Do not use special additives. Change every year or 100 hours in cold weather (below 40 F) or continuous hot weather (above 85 F).
Engine oil	5W-30	Aceite orgánico 5W-30 (la unidad se entrega de fábrica llena con este aceite)			Compruebe el nivel de aceite y, de ser necesario, añada la cantidad apropiada con la viscosidad correcta. No llene en exceso. Consulte 'Recomendaciones para el aceite de motor' para tipo/viscosidad.
Engine oil	5W-30 (factory fill) / 5W-20 GEO (continuous)	Generac proprietary gaseous engine oil (GEO)			Unit comes filled with 5W-30 organic oil; after 25 hour break-in use 5W-20 GEO
Engine oil	SAE 10W-30 or SAE 30	API SF or SG		1.5 Qts w/ filter change (1.2 Qts w/o)	Above 40°F
Engine oil	SAE 30	API Service Class SJ, SL or better			For expected operating temperatures above 32 °F
Engine oil	SAE 30 above 32°F; 10W-30 between 40°F and -10°F; Synthetic 5W-30 10°F and below	API Service Class SJ, SL or better; use no special additives		1.5 Qts	Oil capacity including filter
Engine oil	SAE 40 above 86 F; SAE 30 32-85 F; SAE 20W below 32 F; SAE 10W-30 all seasons	API Service SC, SD, SE or SF		3.0 U.S. quarts	Liquid-cooled 1.2 liter engine with filter change; 2.5 U.S. quarts without filter change.
Engine oil	SAE 5W-20/5W-30	API Service class SG, SH, or SJ	below -7°C		Below 20° F (-7° C)
Engine oil	SAE 5W-30 Synthetic	API Service Class SG, SH or SJ		1.7 Qts	All season; organic break-in oil required before using synthetic oil; unit is supplied with break-in oil
Engine oil	SAE 5W-30 Synthetic (all season)	API Service Class SG, SH or SJ		1.5 Qts	Organic break-in oil required before using synthetic oil; unit is supplied with break-in oil
Engine oil	SAE 5W-30 sintético	API SJ, SL o mejor		1.03 l	9 kW; no usar aditivos especiales
Engine oil	SAE 5W-30 synthetic; SAE 30 above 60 F; SAE 10W-30 20-59 F; SAE 5W-20/5W-30 below 20 F	API Service SF, SF/CC, or SF/CD		1.5 U.S. quarts	Air-cooled V-Twin engine crankcase capacity about 1.5 U.S. quarts. Oil makeup tank capacity about 2.5 U.S. quarts on Model 9067.
Engine oil	SAE 5W-30 synthétique	API classe de service SJ, SL ou supérieure			Huile SAE 5W-30 synthétique pour toutes les plages de température. N'utilisez aucun additif spécial.
Engine oil	Synthetic 5W-20 or 5W-30	API SF or SG		1.5 Qts w/ filter change (1.2 Qts w/o)	Below 40°F
Engine oil	Synthetic 5W-30	API Service Class SJ, SL or better			For expected operating temperatures 10 °F and below
Engine oil	Synthetic SAE 5W-30	API Service Class SJ, SL, or better			Synthetic SAE 5W-30 for all temperature ranges. Do not use special additives. Capacities incl. filter: approx. 1.1 qt (1.03 L) 9 kW; approx. 1.7 qt (1.6 L) 11 kW; approx. 1.9 qt (1.8 L) 16/20/22 kW.
Engine oil	SAE 10W-30	API Service class SG, SH, or SJ	-7°C to 15°C		20° to 59° F (-7° to 15° C)
Fuel		Gas natural: contenido de BTU de por lo menos 1000 BTU/ft3 (37,26 MJ/m3). Gas LP: por lo menos 2500 BTU/ft3 (93,15 MJ/m3)		250.0 gal (946 l)	Tamaño mínimo del tanque de LP es 250 gal (946 l), salvo que los cálculos de la unidad indiquen uno mayor. Solo sistema de extracción de vapor para LP.
Fuel	Gas natural	mínimo 1000 BTU por pie cúbico (37.26 megajulios por metro cúbico)			Reducciones típicas de gas natural 10-20 % respecto a LP
Fuel	Gaz naturel			37.26 mégajoules par mètre cube (1 000 BTU par pied cube) minimum	Teneur en BTU minimale du gaz naturel.
Fuel	Gaz naturel d'au moins 37,26 mégajoules par mètre cube (1 000 BTU par pied cube)	NFPA 54
Fuel	Gaz propane liquide (gazeux)			93.15 mégajoules par mètre cube (2 500 BTU par pied cube) minimum	Capacité de réservoir de gaz propane liquide minimum recommandée de 946 litres (250 gallons).
Fuel	Gaz propane liquide d'au moins 93,15 mégajoules par mètre cube (2 500 BTU par pied cube)	NFPA 58 / ICC IFGC			Réservoir de gaz propane liquide d'une capacité minimale de 946 litres (250 gallons).
Fuel	LP (vapor)	mínimo 2500 BTU por pie cúbico (93.15 megajulios por metro cúbico)		946.0 l	Se recomienda tanque de LP de 250 gal. (946 l) de tamaño mínimo si se convierte de NG a LP
Fuel	LP Vapor	NFPA 58			Vapor withdrawal only. Recommended Btu content at least 2,520 Btus per cubic foot. Required fuel pressure 0.025 to 0.0305 kg/cm2 (10 to 12 inches water column); must never drop below 0.025 kg/cm2 (10 inches water column)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

Code	Name	Meaning	Severity	Action
ADVERTENCIA DEL CARGADOR	ADVERTENCIA DEL CARGADOR	Indicador LED amarillo encendido en cualquier estado.	Warning	Comuníquese con un IASD.
AUXILIARY SHUTDOWN	Desligamento auxiliar	A unidade não inicia.	Shutdown	Coloque as chaves de parada auxiliares em FECHADO (I). Apague o alarme.
BAJA PRESIÓN DEL ACEITE	BAJA PRESIÓN DEL ACEITE	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Revise el nivel de aceite y reponga si es necesario. Si el nivel de aceite es correcto, comuníquese con un IASD.
BAJA VELOCIDAD	BAJA VELOCIDAD	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
BATERÍA BAJA	BATERÍA BAJA	Indicador LED amarillo encendido en cualquier estado.	Warning	Borre la alarma. Navegue hasta BATTERY MENU del MAIN MENU para revisar la batería. Si indica GOOD, comuníquese con un IASD. Si indica CHECK BATTERY, reemplace la batería.
BATTERY PROBLEM	Problema de batería	Yellow LED illuminated in any state.	Warning	Entre em contato com uma IASD.
Battery Problem	Battery Fault	Battery condition poor or battery charger issue	Warning	Inspect battery condition and connections. Contact IASD if needed.
CARGADOR SIN CA	CARGADOR SIN CA	Indicador LED amarillo encendido en cualquier estado.	Warning	Comuníquese con un IASD.
CHARGER MISSING AC	Charger Missing AC	LED amarelo aceso em qualquer estado.	Warning	Entre em contato com uma IASD.
CHARGER WARNING	Charger Warning	Yellow LED illuminated in any state.	Warning	Entre em contato com uma IASD.
CONTROLLER FAULT	Anomalia no controlador	Falha do controlador.	Shutdown	Entre em contato com uma IASD.
Controller Fault	Control Module Failure	Internal controller fault detected	Shutdown	Contact IASD for assistance
DESCONEXIÓN AUXILIAR	DESCONEXIÓN AUXILIAR	La unidad no arranca.	Shutdown	Coloque los interruptores de desconexión auxiliar en posición CERRADA (I).
DOWNLOAD FAILURE	Falha na importação	Falha de download.	Warning	Verifique o ficheiro e tente novamente.
EMERGENCY STOP	Paragem de emergência	Paragem de emergência ativada.	Shutdown	Entre em contato com uma IASD.
ERROR DE CABLEADO	ERROR DE CABLEADO	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
EXERCISE SET ERROR	Exercise Set Error	Exercise timer setting error	Warning	Entre em contato com uma IASD.
EXERCISER NOT SET	Exerciser not set	Indicates the exercise timer has not been set.	Info	Set the exercise timer per Section 3.6.
Exercise Set Error	Exercise Set Error	Warning; displayed if the exercise period becomes corrupted	Warning	Reset the exercise period to clear
FALLA DE ARRANQUE	FALLA DE ARRANQUE	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Verifique que la válvula de cierre de la tubería de combustible esté en la posición ON. Borre la alarma. Arranque la unidad en MANUAL. Si no arranca o funciona de forma dificultosa, comuníquese con un IASD.
FIRMWARE ERROR-7	Erro de firmware 7	Erro de firmware.	Shutdown	Entre em contato com uma IASD.
FIRMWARE ERROR-9	Erro de firmware 9	Erro de firmware.	Shutdown	Entre em contato com uma IASD.
FUEL PRESSURE	Fuel Pressure	Fuel pressure warning	Warning
FUSE PROBLEM	Problema de fusible	Unit will not start in AUTO with utility loss. (Firmware 1.11 and older only.)	Warning	Comprobar el fusible de 7.5 A; sustituir con fusible ATO de 7.5 A si está fundido, o contactar un IASD
HIGH TEMP.	High temperature	High temperature switch contacts close if temperature exceeds approximately 140 C (284 F).	Shutdown	Allow unit to cool; generator restarts and LED resets once temperature returns to a safe level.
HIGH TEMPERATURE	Temperatura elevada	Unit shuts down during operation.	Shutdown	Inspecione a ventilação ao redor do gerador, admissão, exaustão e parte traseira. Se não existirem obstruções, entre em contato com uma IASD.
High Engine Temperature	High Engine Temperature	Shutdown alarm, auto reset; 10 second delay on start-up and 1 second delay before shutdown; contacts close if temperature exceeds approximately 144 °C (293 °F)	Shutdown	Auto reset when condition clears and restart engine if a valid start signal is present
High Temperature	Overheat	Engine operating temperature too high	Shutdown	Inspect ventilation around generator, intake, exhaust, and rear. Ensure no obstructions present.
INSPECCIONE LA BATERÍA	INSPECCIONE LA BATERÍA	Indicador LED amarillo encendido en cualquier estado.	Warning	Inspeccione la batería. Presione ENTER para borrar.
INSPECT BATTERY	Inspect Battery	Yellow LED illuminated in any state.	Warning	Inspect battery; press ENTER to clear.
INTERNAL FAULT	Internal Fault	Internal controller fault	Shutdown	Contact servicing dealer.
Internal Fault	Internal Fault	Shutdown alarm; this alarm cannot be cleared	Shutdown	Call service dealer
LOW BATTERY	Low Battery	Yellow LED illuminated in any state.	Warning	Desactivar la alarma; comprobar batería en BATTERY MENU; si GOOD contactar un IASD, si CHECK BATTERY sustituir la batería
LOW OIL	Low oil pressure	Low oil pressure switch contacts close when oil pressure drops below the 8 psi range.	Shutdown	Add oil; turn AUTO/OFF/MANUAL switch to OFF and then back to AUTO.
LOW OIL PRESSURE	Pressão de óleo baixa	Unit will not start in AUTO with utility loss.	Shutdown	Verifique o nível de óleo e adicione óleo se necessário. Se o nível estiver correto, entre em contato com uma IASD.
LOW VOLTS REMOVE LOAD	Voltaje bajo, retirar carga	Unit will not start in AUTO with utility loss.	Shutdown	Desactivar la alarma, retirar cargas domésticas, poner en AUTO y reanudar
Low Battery	Low Battery	Warning; battery voltage below 11.9 volts for one (1) minute; clears automatically if voltage rises above 12.4 volts; not monitored during crank cycle	Warning	Service or charge battery
Low Oil Pressure	Low Oil Pressure	Shutdown alarm; 5 second delay on start-up and 7 second delay once running; switch contacts close if oil pressure drops below the five (5) PSI range	Shutdown	Verify oil level; unit should not be restarted until oil level is verified
MISWIRE	Miswire / Wiring Error	Unit will not start in AUTO with utility loss.	Shutdown	Contactar un IASD
Maintenance Message	Maintenance Message	Maintenance alert; displayed when a maintenance period expires	Info	Press Enter to confirm reset; clears the alert and resets maintenance counters
NINGUNA	NINGUNA (LED verde parpadeando)	La unidad funciona en AUTO, pero no energiza la casa.	Info	Revise el MLCB del generador (desconexión del generador). Si está encendido, comuníquese con un IASD.
NO ACTIVADA	NO ACTIVADA	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Info	Verifique si la pantalla indica que la unidad no está activada. Consulte Activación.
NO UTILITY SENSE	No utility sense	Flashing LEDs indicate utility sense voltage is not connected or is below 168 volts AC.	Info	Verify utility sense voltage connection.
NOT ACTIVATED	Não ativado	Unit will not start in AUTO with utility loss.	Warning	Refer to activation section in owners manual
OVER CRANK	Overcrank	Unit cranks and rests for a preset time limit then stops cranking when it cannot start.	Shutdown	Set AUTO/OFF/MANUAL switch to OFF and back to AUTO to reset the control board.
OVER SPEED	Overspeed	Protection shuts the unit down if it runs faster than the preset limit.	Shutdown	Contact the nearest Authorized Dealer.
OVER VOLTAGE	Over Voltage	Overvoltage alarm	Shutdown	Contact servicing dealer.
OVERCRANK	Overcrank	Unit will not start in AUTO with utility loss.	Shutdown	Verifique se a válvula de corte da linha de combustível está ligada. Apague o alarme. Inicie em MANUAL. Se não iniciar, entre em contato com uma IASD.
OVERLOAD REMOVE LOAD	Sobrecarga, retirar carga	Unit shuts down during operation.	Shutdown	Desactivar la alarma, retirar cargas domésticas, poner en AUTO y volver a poner en marcha
OVERLOAD WARNING	Overload Warning	Overload warning	Warning	Remova as cargas domésticas do gerador.
OVERSPEED	Sobrevelocidad	Unit will not start in AUTO with utility loss.	Shutdown	Entre em contato com uma IASD.
OVERVOLTAGE	Tensão excessiva	Unit will not start in AUTO with utility loss.	Shutdown	Entre em contato com uma IASD.
Over Crank	Over Crank	Shutdown alarm; occurs if the engine has not started within the specified crank cycle	Shutdown	Reset the control board and restart up to two more times if necessary
Over Speed	Over Speed	Shutdown alarm; 4320 RPM for three (3) seconds or 4500 RPM immediately	Shutdown	Contact the nearest Dealer if this failure occurs
Overcrank	Extended Cranking	Engine failing to start after extended crank attempts	Shutdown	Check fuel supply, spark plugs, and fuel system. Contact IASD for further diagnosis.
Overload	Overload Detected	Electrical load exceeds generator capacity	Shutdown	Remove household electrical loads from generator
Overspeed	RPM Overspeed	Engine running at excessive RPM	Shutdown	Contact IASD for assistance
Overvoltage	Overvoltage	Shutdown alarm; above 110% of rating for greater than three (3) seconds, or above 130% of rating for greater than 0.2 seconds	Shutdown	Reduce electrical load and restart. Contact IASD if issue persists.
PROBLEMA DE BATERÍA	PROBLEMA DE BATERÍA	Indicador LED amarillo encendido en cualquier estado.	Warning	Comuníquese con un IASD.
PÉRDIDA DE DETECCIÓN DE RPM	PÉRDIDA DE DETECCIÓN DE RPM	La unidad funcionaba, se apagó e intenta reiniciarse, o no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Borre la alarma y retire del generador las cargas del hogar. Vuelva a poner en AUTO y reinicie. Si el generador no arranca, comuníquese con un IASD.
RPM SENSE LOSS	RPM Sense Loss	Unit was running and shuts down, attempts to restart	Shutdown	Desactivar la alarma, retirar cargas, poner en AUTO y reanudar; si no arranca contactar un IASD
RPM Sense Loss	RPM Sense Loss	Shutdown alarm; if no valid RPM signal within three (3) seconds during cranking, or lost for one (1) second while running	Shutdown	Control board shuts down, waits 15 seconds, then re-cranks; may re-crank once more before latching out
RPM Sensor Loss	RPM Signal Loss	RPM sensor signal not detected	Shutdown	Contact IASD for assistance
SERVICE A	Servicio A	Yellow LED illuminated, maintenance due	Warning	Realize a manutenção SERVICE A. Pressione ENTER para apagar.
SERVICE B	Servicio B	Yellow LED illuminated, maintenance due	Warning	Realize a manutenção SERVICE B. Pressione ENTER para apagar.
SERVICIO A	SERVICIO A	Indicador LED amarillo encendido en cualquier estado.	Warning	Realice el mantenimiento SERVICIO A. Presione ENTER para borrar.
SERVICIO B	SERVICIO B	Indicador LED amarillo encendido en cualquier estado.	Warning	Realice el mantenimiento SERVICIO B. Presione ENTER para borrar.
SOBRECARGA. RETIRE LA CARGA	SOBRECARGA	La unidad se apaga durante el funcionamiento.	Shutdown	Borre la alarma y retire del generador las cargas del hogar. Vuelva a poner en AUTO y reinicie.
SOBRECORRIENTE DEL MOTOR DE VELOCIDAD GRADUAL	SOBRECORRIENTE DEL MOTOR DE VELOCIDAD GRADUAL	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
SOBREVELOCIDAD	SOBREVELOCIDAD	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
SOBREVOLTAJE	SOBREVOLTAJE	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
STEPPER OVER CURRENT	Stepper Over Current	Stepper motor over current	Shutdown	Contact servicing dealer.
STEPPER OVERCURRENT	Stepper Overcurrent	Unit will not start in AUTO with utility loss.	Shutdown	Entre em contato com uma IASD.
SUBVOLTAJE	SUBVOLTAJE	La unidad no arranca en AUTO con una pérdida de energía eléctrica.	Shutdown	Comuníquese con un IASD.
TEMPERATURA ALTA	TEMPERATURA ALTA	La unidad se apaga durante el funcionamiento.	Shutdown	Inspeccione la ventilación alrededor del generador, además de las secciones de entrada, escape y trasera. Si no hay obstrucciones, comuníquese con un IASD.
UNDER VOLTAGE	Under Voltage	Undervoltage alarm	Shutdown	Contact servicing dealer.
UNDERSPEED	Underspeed	Unit will not start in AUTO with utility loss.	Shutdown	Entre em contato com uma IASD.
UNDERVOLTAGE	Undervoltage	Unit will not start in AUTO with utility loss.	Shutdown	Entre em contato com uma IASD.
USB WARNING	Aviso de USB	Aviso relacionado ao dispositivo USB.	Warning	Tente novamente com USB de melhor qualidade. Os nomes dos ficheiros no USB não podem ter mais de 8 caracteres.
Under-frequency	Under-frequency	Shutdown alarm; if generator stays under frequency for more than 30 seconds; setting is 50 Hz	Shutdown	Check generator output

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjust Valve Clearance adjustment

⚠ Allow engine to cool before adjusting valve clearance.

Tools: feeler gauge, 10 mm wrench, 13 mm wrench, 14 mm wrench, 8 mm wrench, 10 mm Allen wrench, torque wrench

Make sure piston is at TDC of compression stroke (both valves closed).
Remove spark plug wire(s) and position away from plugs.
Remove spark plug(s).
Remove the four screws attaching valve cover; remove and discard gasket.
Loosen rocker jam nut (10 mm wrench 9-11 kW; 13 mm wrench 16-22 kW).
Turn pivot ball stud (14 mm wrench 9 kW; 8 mm wrench 11 kW; 10 mm Allen 16-22 kW) while checking clearance with feeler gauge.
Hold rocker arm jam nut in place as pivot ball stud is turned.
When clearance correct, hold pivot ball stud and tighten rocker arm jam nut to torque spec.
Recheck valve clearance after tightening jam nut.
Install new valve cover gasket.
Install valve cover; tighten fasteners in cross pattern to torque spec.
Install spark plugs and torque to 18 ft-lbs (25 Nm).
Reattach spark plug wire to spark plug.
Repeat process for other cylinder if necessary.

Adjusting GH-410/GT-530/990/999 Valve Clearance adjustment

⚠ The engine should be cool before checking.

Tools: Feeler gauge, 10mm allen wrench, Socket wrench

Remove spark plug wires and position wires away from plugs.
Remove spark plugs.
Make sure the piston is at Top Dead Center (TDC) of its compression stroke.
Make sure the engine is at 60 to 80 F.
Remove the four screws attaching the valve cover.
Loosen the rocker jam nut.
Use a 10mm allen wrench to turn the pivot ball stud while checking clearance between the rocker arm and valve stem with a feeler gauge.
When valve clearance is correct, hold the pivot ball stud in place and tighten the rocker arm jam nut to 174 in/lbs torque.
Recheck valve clearance.
Install new valve cover gasket and re-attach the valve cover.
Install spark plugs and re-attach the spark plug wire.
On the GT-530 and GT-990/999, repeat the process for the other cylinder.

Adjusting GH-410/GT-990 Valve Clearance adjustment

⚠ Hold the rocker arm jam nut in place as you turn the pivot ball stud.

Tools: #2 or #3 Phillips screwdriver, 10mm allen wrench, feeler gauge, socket wrench

Make sure the engine is at room temperature.
Remove the spark plug wire from the spark plug.
Remove the four screws attaching the valve cover.
Set the piston at Top Dead Center of its compression stroke.
Loosen the rocker jam nut; turn the pivot ball stud; check clearance with a feeler gauge.
Tighten the rocker arm jam nut to 174 in/lbs.
Install a new valve cover gasket and re-attach the valve cover.
Re-attach the spark plug wire; on GT-990 repeat for the other cylinder.

Adjusting GT-530/990/999 Valve Clearance adjustment

⚠ Check after first six months of operation

Tools: 10mm allen wrench, feeler gauge, torque wrench

Engine should be cool before checking
Remove spark plug wires and spark plugs
Rotate flywheel nut clockwise to bring piston to TDC of compression stroke
Ensure engine is at 60-80°F
Remove the four screws attaching the valve cover
Loosen rocker jam nut, turn pivot ball stud with 10mm allen wrench while checking clearance with feeler gauge
Set clearance to 0.002-0.004 inch (0.05-0.1mm)
Tighten rocker arm jam nut to 174 in/lbs torque while holding pivot ball stud
Recheck valve clearance
Install new valve cover gasket and re-attach valve cover
Install spark plugs and re-attach wires
Repeat for other cylinder

Adjusting GT-990 Valve Clearance adjustment

Tools: #2 or #3 phillips screwdriver, 10mm allen wrench, feeler gauge

Make sure engine is at room temperature between 60 and 80 F.
Make sure the spark plug(s) are removed.
Remove the four valve cover screws with a #2 or #3 Phillips screwdriver.
Rotate the engine by hand to bring the piston to Top Dead Center of its compression stroke.
Loosen the rocker jam nut.
Turn the pivot ball stud with a 10 mm allen wrench while checking clearance with a feeler gauge.
Hold the pivot ball stud and tighten the rocker arm jam nut; recheck clearance.
Install new valve cover gasket and re-attach valve cover.
Re-attach the spark plug wire.
Repeat the process for the other cylinder.

Adjusting Magneto Flywheel Gap adjustment

⚠ Air gap between ignition magneto and flywheel on single cylinder engines is not adjustable.

Tools: 0.008-0.012 inch thickness gauge

Rotate the flywheel until the magnet is under the module (armature) laminations.
Place a 0.008-0.012 inch (0.20-0.30mm) thickness gauge between flywheel magnet and module laminations.
Loosen the mounting screws and let the magnet pull the magneto down against the thickness gauge.
Tighten both mounting screws.
To remove the thickness gauge, rotate the flywheel.
Repeat the above procedure for the second magneto.

Adjusting Valve Clearance adjustment

⚠ Risk of Burn. Allow the engine to cool before performing the following procedure.

Tools: feeler gauge, 10 mm wrench, 13 mm wrench, 14 mm wrench, 10 mm hex key

Remove spark plug wire(s) and position away from spark plug(s).
Remove spark plug(s).
Remove the four screws attaching valve cover. Remove and discard gasket.
Verify piston is at TDC of its compression stroke (both valves closed).
Loosen rocker jam nut using a 10 mm wrench (10 kW units) or 13 mm wrench (20-24 kW units).
Turn pivot ball stud using a 14 mm wrench (10 kW) or 10 mm hex key (20-24 kW) while checking clearance with a feeler gauge.
Hold pivot ball stud and tighten rocker arm jam nut.
Inspect valve clearance to verify it did not change.
Install new valve cover gasket and valve cover; tighten fasteners in a cross pattern.
Install spark plug(s) and tighten to 18 ft-lbs (25 Nm); attach spark plug wires.
Repeat process for other cylinder if equipped.

Adjusting Valve Clearance GH-410/GT-530/990/999 adjustment

⚠ Check valve clearance after first six (6) months of operation.

Tools: 10mm allen wrench, Feeler gauge, Socket and socket wrench

Engine should be cool before checking; clearance 0.002-0.004 inch needs no adjustment.
Remove spark plug wires and spark plugs.
Set piston at Top Dead Center of its compression stroke.
Remove four screws attaching the valve cover.
Loosen rocker jam nut; turn pivot ball stud with 10mm allen wrench.
Set clearance to 0.002-0.004 inch (0.05-0.1 mm).
Hold pivot ball stud and tighten jam nut to 174 in/lbs torque.
Install new valve cover gasket and re-attach valve cover.

Adjusting the Fuel Regulator (Natural Gas Only) adjustment

⚠ Avoid overspeeding the engine.

Tools: Frequency meter

Turn off utility power to the main distribution panel.
Allow the generator to start; confirm no-load frequency (roof open, door off) is 63-63.5 Hz.
Transfer load to emergency circuits and fully load the generator.
Connect a frequency meter to the output lugs of the main line circuit breaker.
Slowly turn the adjustment screws one at a time until the highest frequency is read.
When maximum frequency is reached, turn both adjustment screws 1/4 turn clockwise.
Turn utility power back on and allow the generator to shut down.

Adjusting the Regulator (Natural Gas Only) adjustment

⚠ Do not remove any of the set pins.

⚠ Be careful to avoid overspeeding the engine.

Tools: frequency meter

Turn off utility power to the main distribution panel.
Allow the generator to start; confirm no load frequency is 63-63.5 Hz.
Transfer load to emergency circuits and fully load the generator.
Connect a frequency meter to the output lugs of the main line circuit breaker.
Slowly turn the adjustment screws one at a time until the highest frequency is read.
Turn both adjustment screws 1/4 turn counterclockwise.
Turn utility power back on and allow the generator to shut down.

Ajustar a folga das válvulas adjustment

⚠ Risco de queimaduras. Deixe o motor esfriar antes de executar o procedimento.

Tools: Chave de 10 mm, Chave de 13 mm, Chave de 14 mm, Chave sextavada de 10 mm, Calibrador

Remova os fios das velas de ignição e remova as velas de ignição.
Remova os quatro parafusos que prendem a tampa da válvula; descarte a junta.
Verifique se o pistão está no TDC do seu curso de compressão.
Solte a contraporca do balanceiro (C) com chave de 10 mm ou 13 mm.
Gire o pino de esfera articulada (D) com chave de 14 mm ou sextavada de 10 mm e ajuste a folga.
Aperte a contraporca do braço oscilante e inspecione a folga novamente.
Instale a nova junta e as tampas das válvulas; aperte em padrão transversal.
Instale as velas e aperte a 25 Nm; conecte os fios das velas.

Ajuste de la luz de válvulas adjustment

⚠ Dejar enfriar el motor antes de ajustar.

⚠ Iniciar los cuatro tornillos antes de apretar.

Tools: Calibre de espesores, Llaves de 8/10/13/14 mm, Llave de casquillo, Casquillo grande

Cerrar la válvula de combustible y desconectar la batería.
Retirar cable(s) de bujía y alejarlos.
Retirar la(s) bujía(s).
Llevar el pistón al PMS de la carrera de compresión.
Retirar los cuatro tornillos de la cubierta de válvulas y desechar la junta.
Aflojar la contratuerca del balancín.
Girar el prisionero de bola pivote para ajustar la luz con calibre.
Sostener el prisionero y apretar la contratuerca; verificar y reinstalar con junta nueva.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
		0 – c.c. (-)	NOIR no 3	Fil de mise à la terre normal; obligatoire si jumelé à un commutateur de transfert de gestion intelligente de l'alimentation de Generac.
		23	BLANCO Núm. 5	Cable de señal lógica del control de transferencia
		23 (White #5)	E	Transfer Control Signal Wire
		Control system interconnections	N1, N2, 0, 15B, 23	Can be run in same conduit as AC power if length < 35 feet and all wiring rated 600V
		Longueur de fil 1 à 35 m (1 à 115 pi)	Calibre 18 AWG	Conducteurs en cuivre seulement.
		Longueur de fil 35 à 56 m (115 à 185 pi)	Calibre 16 AWG	Conducteurs en cuivre seulement.
		Longueur de fil 56 à 89 m (185 à 295 pi)	Calibre 14 AWG	Conducteurs en cuivre seulement.
		Longueur de fil 89 à 140 m (295 à 460 pi)	Calibre 12 AWG	Conducteurs en cuivre seulement.
		Neutral for battery charger	WHITE NEU/00	Must be connected to keep battery charged whether unit is running or not
	1	Connect a 2008 and later load center switch to a pre-2008 air-cooled generator: Wire 0 will not be utilized. Remove battery charger from the transfer switch. Connect N1 (BLU) to N1 (YEL), N2 (YEL) to N2 (YEL), 23 (BRN) to 23 (WHT), 194 (ORG) to 15B (RED) using UL approved wire nuts.	N1, N2, 23, 194, 15B, 0	Battery charger in transfer switch will not be utilized in operation of the generator.
	1	Connect a pre-2008 load center switch to a current or future air-cooled generator: Wire 0 will not be utilized. Connect N1 (BLU) to N1 (YEL), N2 (YEL) to N2 (YEL), 23 (BRN) to 23 (WHT), 194 (ORG) to 15B (RED) using UL approved wire nuts.	N1, N2, 23, 194, 15B, 0	Wire 194 changed to 15B on current model air-cooled generators.
0 VCC		0	NEGRO Núm. 3	CC (-) Cable común de conexión a tierra. Requerido si el generador está apareado con un interruptor de transferencia de gestión de alimentación inteligente Generac.
12 V c.c.		194 – c.c. (+)	ROUGE no 4	Pour les commandes de transfert.
12 VCC		194	ROJO núm. 4	CC (+) para los controles de transferencia
12 VDC		194 (Red #4)	D	DC (+) 12 VDC for Transfer Controls
12 VDC		DC (+) 12 VDC for transfer controls	RED 194
12 VDC		DC (-) common ground wire	BLACK 0
12 VDC		Transfer control signal wire	WHITE 23	Required if generator is paired with optional Digital Power Management (DPM) smart technology
120	1	Battery charger AC input to generator backed-up 120VAC circuit	120VAC hot, neutral	Connect via wire nuts
120 V c.a.		T1	BLEU no 3	Avec fusible 120 V c.a. pour le chargeur de la batterie; doit être branché pour que la batterie demeure chargée.
120 VAC		Fused 120 VAC for battery charger	BLUE T1	Must be connected to keep battery charged whether unit is running or not
120 VAC		T1 (White #3)	B	Fused 120VAC for Battery Charger
120 VCA		T1	AZUL Núm. 3	Con fusible para el cargador de baterías (debe estar conectado para mantener la batería cargada, esté o no funcionando la unidad)
120/208	3	parallel wye	S1 through S12; bolted junctions: 4,5,6,10,11,12 to Neutral (00); S1 and S7 to Line E1; S2 and S8 to Line E2; S3 and S9 to Line E3	Voltage Code B. Six coils, twelve leads brought out to AC connection panel.
120/240	1	3-wire	Leads 11 and 44 are hot; junction of Leads 22 and 33 is neutral	Voltage Code A. Stator AC power windings each supply 120 volts AC; in series they supply 240 volts AC.
120/240	1	GENERATOR (STANDBY) source power cables to ATS GENERATOR supply terminals	E1, E2	200A models
120/240	1	Non-essential customer LOAD leads to LSS switch terminals	E1, E2	Load shed switch
120/240	1	UTILITY (NORMAL) power source cables to top of UTILITY SERVICE DISCONNECT circuit breaker	N1, N2	200A models
120/240	1 or 3	delta	Two of six stator coils are double-wound. For 1-phase: connect 240 V loads across Lines E1 and E2; connect 120 V loads across Lines E1 to 00 or E3 to 00.	Voltage Code D.
240	1	Transfer switch terminal lugs: connect utility source hot lines to N1 and N2; connect standby source hot lines (E1, E2) to E1 and E2; connect load lines from T1 and T2 to electrical load circuit; connect UTILITY, STANDBY and LOAD neutral lines to neutral block.	N1, N2, E1, E2, T1, T2	In 1-phase systems with a 2-pole transfer switch.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Generac GT990 family

179

Part #	Description	Category
0C3040	PRE-CLEANER	Air filter
0C8127	ELEMENT AIR CLEANER	Air filter
0D3262	AIR FILTER ELEMENT	Air filter
0D4511	PRECLEANER, AIR	Air filter
0D9723	ELEMENT, AIR FILTER	Air filter
100-025	Air Filter	Air filter
C8127	Engine Air Cleaner/Air Filter	Air filter
083049	REGULATOR VOLTAGE	Avr
0F9719	ASSY PCB VREG AIR COOLED	Avr
0C1112	BELT,V-RIB 4LX42.5"	Belt
066386	ASSEMBLY, BRUSH HOLDER	Brush
0D6313	FILTER, FUEL	Fuel filter
021713B	CYLINDER HEAD GASKET	Gasket
076701	CRANKCASE GASKET	Gasket
090239	GASKET, EXHAUST MANIFOLD	Gasket
0C2977	GASKET, CRANK CASE	Gasket
0C2978	GASKET, HEAD	Gasket
0C2979	GASKET, VALVE COVER	Gasket
0C3005	GASKET, BREATHER COVER	Gasket
0C3043	GASKET, MANIFOLD / PORT	Gasket
0C3150	ROCKER COVER GASKET	Gasket
0C4138	GASKET, EXHAUST PORT	Gasket
0C4647	GASKET, SOLENOID	Gasket
0C6069	GASKET, DIAPHRAGM	Gasket
0D2559	GASKET, ALTERNATOR AIR DUCT	Gasket
0D4010	KIT GASKET	Gasket
0D4023	GASKET, MANIFOLD TO CARB (GT-990)	Gasket
0D4024	GASKET, CARB TO SPACER	Gasket
0D4026	GASKET, CARB TO SPACER (GT-990)	Gasket
0D5282	GASKET, MANIFOLD TO CARBURETOR	Gasket
0D6327	GASKET, SPITBACK	Gasket
0E0572	GASKET,CARB TO INTAKE MANIFOLD	Gasket
0E0573	GASKET,CARB TO ADAPTOR	Gasket
0E1078A	GASKET, EXHAUST BASE	Gasket
030340	Hose, Fuel, 4.5" LG.	Hose
048031C	CLAMP HOSE BAND 1/4	Hose
0C3036	HOSE, BREATHER	Hose
0C3036A	HOSE, BREATHER	Hose
0C9093	HOSE, BREATHER	Hose
0C9093A	HOSE, BREATHER	Hose
0C9806	HOSE, 3/8 I.D. X 6 LONG	Hose
0D3083	ASSEMBLY, OIL DRAIN HOSE	Hose
0E5079	HOSE, BREATHER	Hose
0F7065	3 FT HOSE RES 1/2	Hose
0F9176	HOSE 1/4 ID	Hose
070185	FILTER, OIL	Oil filter
070185B	FILTER, OIL	Oil filter
070185F	Oil Filter	Oil filter
100-030	Oil Filter	Oil filter
70185	FILTER, OIL	Oil filter
021533	SET, PISTON RING 90MM	Service part / kit
022097	WASHER LOCK M6-1/4	Service part / kit
022473	WASHER FLAT 1/4-M6 ZINC	Service part / kit
022676	FUSE AGC-15A.	Service part / kit
028578	FUSE 10A X AGC10	Service part / kit
031971	BEARING #6205 2NSE C3 E SRI2 S	Service part / kit
043790A	BARBED EL 90 3/8NPT X 3/8 VS	Service part / kit
049721	SCREW HHC M6-1.0 X 35 G8.8 BLK	Service part / kit
052857	NUT LOCK FLANGE M6-1.0	Service part / kit
0536210209	ASSEMBLY, WIRE	Service part / kit
056482	BEARING	Service part / kit
066849B	SCREW HHTT M5-0.8 X 8mm	Service part / kit
071980	PIN PISTON D20	Service part / kit
071983	RETAINER, PISTON PIN 20	Service part / kit
072694	STUD, ROCKER ARM PIVOT	Service part / kit
073159	BEARING	Service part / kit
073590A	FUSE 5A X BUSS	Service part / kit
073591	FUSE HOLDER	Service part / kit
074908	SCREW HHTT M5-0.8 X 10 BP	Service part / kit
078699E	SLEEVE, SEAMED DOWEL 10 DIA.	Service part / kit
083897	TAPPET, SOLID	Service part / kit
086515	KEEPER, VALVE SPRING	Service part / kit
086516	VALVE, EXHAUST	Service part / kit
087680	NUT WING M6-1.0	Service part / kit
090388	SCREW HHTT M6-1.0 X 12 ZINC	Service part / kit
093064	ASSEMBLY, OIL FILL CAP	Service part / kit
093873	WASHER, LOCK RIB M6	Service part / kit
099727	FUSE 5A X AGC5	Service part / kit
0A1801	ASSEMBLY, BATTERY CHARGER ENGINE	Service part / kit
0A9611	FUSE 7.5A	Service part / kit
0C2229	VALVE, INTAKE	Service part / kit
0C2237	XFRSW HSB 100A 2P 250V	Service part / kit
0C2967	PISTON, LC	Service part / kit
0C2969	ASSEMBLY, CONNECTING ROD (GT-990)	Service part / kit
0C2976	SCREW HHFC M8-1.25 X 65	Service part / kit
0C2981	ROCKER, COVER	Service part / kit
0C3003	SEPARATOR, OIL BREATHER	Service part / kit
0C3006	SCREW, HHFC M10-1.5 X 55	Service part / kit
0C3009	SPRING, OIL RELIEF	Service part / kit
0C3010	BALL, 1/2D OIL RELIEF	Service part / kit
0C3011	COVER, OIL RELIEF	Service part / kit
0C3026	COOLER, OIL	Service part / kit
0C4680	PLUNGER, LP REGULATOR ASSEMBLY	Service part / kit
0C4706	DIAPHRAGM, TWIN REGULATOR	Service part / kit
0C4739	SCREW PPHM M3-0.5 X 6	Service part / kit
0C5313	SCREEN, OIL PICKUP	Service part / kit
0C5315	GEROTOR, OUTER	Service part / kit
0C5371	WASHER, VALVE SPRING	Service part / kit
0C5372	ASSEMBLY, BREATHER	Service part / kit
0C5729	ASSEMBLY, CRANKCASE HOUSING WITH SLEEVE	Service part / kit
0C5731	ASSEMBLY, HOUSING COVER WITH SLEEVE	Service part / kit
0C5760A	JET, GN 410 ENGINE LP (7KW)	Service part / kit
0C5760G	JET, GT990 NAT GAS	Service part / kit
0C5760J	JET, GN 410 ENGINE LP	Service part / kit
0C5764	SPRING, REGULATOR	Service part / kit
0C5765	SOLENOID, TWIN REGULATOR	Service part / kit
0C6070	SPRING-SOLENOID PLUNGER	Service part / kit
0C8526	CARBURETOR (GT-990)	Service part / kit
0C8566	SCREW HHFC M6-1.0 X 20 G8.8	Service part / kit
0C8808	HOOK, LIFTING	Service part / kit
0D2157	SCREW SHC M6-1.0 X 50 C8.8	Service part / kit
0D2274	RETAINER, VALVE SPRING	Service part / kit
0D2774B	BASE, AIRBOX	Service part / kit
0D2775	COVER, AIRBOX	Service part / kit
0D2930	VALVE, SUMMER / WINTER	Service part / kit
0D3867	SPRING, VALVE	Service part / kit
0D3998	NUT HEX M8-1.0 G8 YEL CHR	Service part / kit
0D4012	KIT BREATHER ASSEMBLY	Service part / kit
0D4015	KIT OIL RELIEF	Service part / kit
0D4040E	ASSEMBLY, CRANKSHAFT HORIZONTAL DIRECT DRIVE (GT-990)	Service part / kit
0D4041	ASSEMBLY, CAMSHAFT & GEAR	Service part / kit
0D4183	ADAPTOR, SPIT BACK	Service part / kit
0D4522	CONTROLLER ASSEMBLY	Service part / kit
0D4570	CAP, FUEL WITH GAUGE & VENT	Service part / kit
0D4575	BATTERY U1	Service part / kit
0D4612	SNORKEL, AIR INTAKE	Service part / kit
0D4788	PLUG STD PIPE 3/8 STEEL SQ HD	Service part / kit
0D5014A	KNOB, AIRBOX 17mm	Service part / kit
0D5014B	KNOB, AIRBOX 95MM	Service part / kit
0D5125	SPRING, WINTER/SUMMER VALVE	Service part / kit
0D5133	SCREEN, SPARK ARRESTOR	Service part / kit
0D5269	ROCKER, COVER	Service part / kit
0D5313	ROCKER ARM	Service part / kit
0D5698A	JET IDLE PRIMER PHILLIPS HD	Service part / kit
0D6007	KIT PISTON & RINGS	Service part / kit
0D6008	KIT GEAR COVER	Service part / kit
0D6020	STUD M6-1.0 X 73	Service part / kit
0D6021	STUD, METRIC	Service part / kit
0D6024	PLATE, PUSH ROD GUIDE	Service part / kit
0D6143	TUBE, HEAT RISER 50.8 I.D.	Service part / kit
0D8067A	ASSEMBLY, HEAD #1	Service part / kit
0D8067B	ASSEMBLY, HEAD #2	Service part / kit
0D8675A	KIT HEAD ASSEMBLY CYLINDER 1	Service part / kit
0D8675B	KIT HEAD ASSEMBLY CYLINDER 2	Service part / kit
0D9852	ASSEMBLY IGNITION COIL	Service part / kit
0D9853D	PUSHROD 144.6	Service part / kit
0E1010A	JET, GT990 LP GAS	Service part / kit
0E3372B	SEPARATOR, OIL BREATHER	Service part / kit
0F1338A	ASSY, IGN COIL W/DIODE NO ADV	Service part / kit
0F1338B	ASSY, IGN COIL W/DIODE NO ADV	Service part / kit
0F5022	SOLENOID COIL, 12VDC	Service part / kit
0F9035	CARBURETOR (GT-990)	Service part / kit
0C2995	GEROTOR, INNER	Pump
0C2996	GEROTOR, OUTER	Pump
0D4123	ASSEMBLY, OIL PUMP	Pump
0D4123A	ASSEMBLY, OIL PUMP	Pump
0F6263	Impulse pump	Pump
072655	SEAL, 35 I.D. CRANKSHAFT	Seal
078672	SEAL, VALVE STEM D7	Seal
097934	O-RING, CHECK VALVE	Seal
0C2993	SEAL, GOVERNOR SHAFT	Seal
0C3007	SEAL, 42 I.D. CRANKSHAFT	Seal
0C3008	SEAL, 38 I.D. CRANKSHAFT	Seal
0C5943	SEAL, OIL PASSAGE	Seal
0C6066	SEAL, INLET REGULATOR	Seal
0CL3007	SEAL, 42 I.D. CRANKSHAFT	Seal
0E6884	SEAL, ALTERNATOR SHAFT	Seal
0E9842	SEAL, 42 I.D. CRANKSHAFT	Seal
0E9843	SEAL, 38 I.D. CRANKSHAFT	Seal
075281	SWITCH, HIGH TEMPERATURE	Sensor
099236	Switch Oil Pressure Switch 8 PSI 1 Pole	Sensor
0A8584	Switch	Sensor
0C3025	SWITCH, OIL PRESS	Sensor
0E1497	SWITCH, OIL HIGH TEMP	Sensor
072347	SPARK PLUG	Spark plug
0D4529	SPARKPLUG	Spark plug
0E7585	SPARK PLUG	Spark plug
RC12YC	Spark Plug	Spark plug
RC14YC	Recommended Spark Plug	Spark plug

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Aftermarket parts that fit this engine

A0000501971 FridayParts $109.99 0G3224TA FridayParts $29.99 0G3224TB FridayParts $29.99 FP-XP-0033262

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Common questions

What is the oil capacity of the Generac GT-990?

The Generac GT-990 engine has an oil capacity of 1.5 liters.

What is the displacement of the Generac GT-990?

The Generac GT-990 has a displacement of 992.0 liters with 2 cylinders.

Which generators use the Generac GT-990 engine?

The Generac GT-990 powers 4 generator set(s), including Generac 8.1 GN, Generac Model 004666, Generac Model 005011, Power Systems GT-990.

How often should you change the oil in the Generac GT-990?

The Generac GT-990 oil change interval is every 150 hours.

What is a common problem with the Generac GT-990 engine?

A commonly reported issue on generators using the Generac GT-990 is: The engine will not crank.. Cause: 1. Fuse blown 2. Loose, corroded or defective battery cables 3. Defective starter contactor 4. Defective starter motor. Fix: 1. Replace fuse. 2. Tighten, clean or replace as necessary. 3. * 4. *.

Generac GT-990 Engine

Engine specifications

Generator sets powered by this engine

Troubleshooting

Symptoms & remedies

Common problems

Maintenance schedule

Repair guides

Service intervals

Service specifications

Recommended fluids

Fault codes

Procedures

Voltage reconnection

Parts cataloged across the Generac GT990 family

Aftermarket parts that fit this engine

Common questions