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Generac GH-426 Engine

The Generac GH-426 is a 0.43 L engine rated at 3600 rpm. It powers generator sets from Generac, including the G0070420. It holds 1.03 L (0.3 gal) of oil.

Also known as: GH-426, Generac GH-426

Part of the Generac GH426 engine family — 2 variants share parts & fitment.

0.426 L

Displacement

3600 rpm

Rated speed

1.03 L

Oil capacity

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

Engine specifications

Oil capacity	1.03 L
Displacement	0.426 L
Rated speed	3600 rpm

Generator sets powered by this engine

Generac G0070420

How to read your Generac engine serial & model number →

Common problems

Unit will not start in AUTO with utility loss
Cause: Start delay countdown
Fix: If the start up delay is greater than expected, contact servicing dealer to adjust from 2 to 1500 seconds.
No transfer to standby after utility source failure
Cause: MLCB (generator disconnect) is OFF (OPEN)
Fix: Reset generator disconnect to ON (CLOSED).
Yellow LED illuminated in any state LOW BATTERY
Fix: Clear alarm. Using the control panel, check the battery by navigating to the BATTERY MENU option from the MAIN MENU. If battery condition displays GOOD, contact an IASD. If control panel displays CHECK BATTERY, replace the battery.
Engine starts hard and runs rough
Cause: Air cleaner plugged or damaged
Fix: Check and clean air cleaner.
Unit consumes large amounts of oil
Cause: Excessive engine oil
Fix: Adjust oil to proper level.
Engine will not crank
Cause: Blown fuse
Fix: Correct short circuit condition by replacing 7.5 amp fuse in generator control panel. Contact an Independent Authorized Service Dealer (IASD) if fuse continues to blow.
Engine cranks but will not start
Cause: No fuel
Fix: Replenish fuel / turn on fuel valve.
Unit will not start in AUTO with utility loss — LED: RED LOW OIL PRESSURE
Fix: Check oil level and add oil as needed. If oil level is correct, contact an IASD.
No AC output from generator
Cause: Main line circuit breaker (MLCB) (generator disconnect) is OFF (OPEN)
Fix: Reset generator disconnect to ON (CLOSED).
Yellow LED illuminated in any state — LED: YELLOW LOW BATTERY
Fix: Clear alarm. Using the control panel, check the battery by navigating to the BATTERY MENU option from the MAIN MENU. If battery condition displays GOOD, contact an IASD. If control panel displays CHECK BATTERY, replace the battery.
Unit shuts down during operation HIGH TEMPERATURE
Fix: Check ventilation around the generator, intake, exhaust, and rear of generator. If no obstructions are present, contact an IASD.
Generator is set to OFF, but the engine continues to run
Cause: Controller wired incorrectly
Fix: Contact an IASD for assistance.
Undervoltage — ALARM 1900
Cause: Prolonged Under-Voltage. Undervoltage due to loss of voltage. Below 80% for 10+ seconds
Fix: Preliminary Output Voltage Test (firmware v1.12 and above). Note: Update controller to latest firmware
RPM Sensor — ALARM 1501
Cause: Twin Cylinder+Running. Twin Cylinder Running faults to RPM Sensor Loss. Possible Causes: air pocket in fuel line, dirty fuel, missing ignition pulse (loss of one of the primary coils)
Fix: Test 50 and Test 64
Overspeed — ALARM 1200
Cause: Prolonged (60 Hz on a 50 Hz unit, 72Hz on 60Hz unit) over specified Hz for 3 seconds. Possible cause: Stepper motor/mixer body assembly issue
Fix: Test 12

Compiled from service & troubleshooting documentation across every generator set that uses the Generac GH-426.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			0E9371A	400 hr	Amazon eBay $19.99
Oil filter			070185E	200 hr	Amazon eBay $30.00 NAPA $9.09 FridayParts $45.99
Battery	12 volts, groupe 26R, 540 ADF minimum ou groupe 35 AGM, 650 ADF minimum		0H3421S	400 hr	Amazon eBay $283.32
Oil	Synthetic SAE 5W-30 for all temperature ranges; API Service Class SJ, SL, or better; no special additives	1.8	—	200 hr
Spark plug	RL87YC ou équivalent		0E9368	400 hr	Amazon eBay $4.99 NAPA $4.07

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

Repair guides

Step-by-step procedures compiled from the Generac service manual for this engine.

Service intervals

Item	Action	Hours	Months	Notes
Exercise	Test	168 hr		Weekly exercise
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
Engine oil	Change	200 hr	24 mo	Up to a 2 year/200 hour oil change interval.
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.
Service Schedule A	Other	200 hr	24 mo	200 hours or 2 years
Bougies d'allumage	Clean	400 hr	48 mo	Nettoyer les bougies, vérifier l'écartement ou les remplacer. Calendrier A et Calendrier B.
Bujías	Replace	400 hr	48 mo	Programa B; limpiar, comprobar separación y sustituir
Engine air filter	Replace	400 hr	48 mo	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
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
Service Schedule B	Other	400 hr	48 mo	400 hours or 4 years
Spark plugs	Replace	400 hr	48 mo	Every Four Years or 400 Hours (Schedule B); clean, check gap, replace
Valve clearance	Adjust	400 hr	48 mo	First service — Every Four Years or 400 Hours (Schedule B); also check/adjust after first 25 hours of operation
Batterie (état, niveau d'électrolyte et état de chargement)	Check		12 mo	Chaque année, Calendrier A (tous les deux ans ou toutes les 200 heures) et Calendrier B (tous les quatre ans ou toutes les 400 heures).
Battery condition, electrolyte level, and state of charge	Check		12 mo	Every Year (Schedule A and B)
Infiltration d'eau	Check		12 mo	Chaque année.
Sediment trap	Clean		12 mo	Inspect/clean sediment trap every year; consult local codes and guidelines.

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	Generator flange inside engine plate	1/32	inch	approximately
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	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	0.040	in (1.02 mm)	16/20/22 kW (GT-999)
Gap	Spark plug gap	.030
Gap	Spark plug gap	0.508	mm
Gap	Spark plug gap	0.76	mm
Gap	Spark plug gap	1.02	mm
Gap	Spark plug gap (11 kW)	0.030	in (0.76 mm)
Gap	Spark plug gap (16/20/22 kW)	0.040	in (1.02 mm)
Gap	Spark plug gap (9 kW)	0.020	in (0.508 mm)
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	Exercise time length (16-22 kW)	5	minutes
Other	Exercise time length (9-11 kW)	12	minutes
Other	Retardo de calentamiento con Arranque inteligente en frío	30	segundos	temperatura ambiente por debajo de la temperatura fijada
Other	Retardo de calentamiento normal	6	segundos	temperatura ambiente en o sobre la temperatura fijada
Other	Utility failure detection threshold	65	% of nominal (for five consecutive seconds)
Other	Utility restoration threshold	80	% of nominal (for 15 consecutive seconds)
Pressure	Compression pressure	150	psi	cold engine
Pressure	Compression pressure	160	psi	cold engine
Pressure	Compression pressure	165	psi	cold engine
Pressure	Compression pressure	190	psi	cold engine
Pressure	Fuel flow / pressure	4 to 8	oz
Pressure	Fuel pressure at regulator - LP	10-12	in water column (19-22 mm Hg)
Pressure	Fuel pressure at regulator - Natural Gas	3.5-7.0	in water column (9-13 mm Hg)
Pressure	Fuel pressure at utility side of regulator	7 to 14	inches water column
Pressure	Fuel pressure to regulator (LP)	10-12	in water column (19-22 mm Hg)	LP gas
Pressure	Fuel pressure to regulator (NG)	3.5-7.0	in water column (9-13 mm Hg)	natural gas
Pressure	Normal oil pressure	35-40	psi	engine running
Pressure	Oil pressure switch rating	10	psi
Pressure	Oil pressure switch rating	8	psi
Pressure	Presión de combustible al regulador (LP)	10–12	in de columna de agua (19–22 mm de mercurio)
Pressure	Presión de combustible al regulador (gas natural)	3.5–7.0	in de columna de agua (9–13 mm de mercurio)
Pressure	Presión de combustible requerida - gas natural	3,5–7,0	pulgadas de columna de agua	En la entrada de combustible del generador (7–13 mm de mercurio)
Pressure	Presión de combustible requerida - vapor de propano líquido	10–12	pulgadas de columna de agua	En la entrada de combustible del generador (19–22 mm de mercurio)
Pressure	Pression de carburant au régulateur (gaz naturel)	9 à 13	mm Hg (3,5 à 7 po de colonne d'eau)
Pressure	Pression de carburant au régulateur (propane liquide)	19 à 22	mm Hg (10 à 12 po de colonne d'eau)
Pressure	Pression de carburant — gaz naturel	7 à 13 mm Hg (3,5 à 7 po de colonne d'eau)	mm Hg / po colonne d'eau	À l'entrée de carburant du générateur
Pressure	Pression de carburant — vapeur de propane liquide	19 à 22 mm Hg (10 à 12 po de colonne d'eau)	mm Hg / po colonne d'eau	À l'entrée de carburant du générateur
Resistance	Fault Relay Post 30 to 87a	.2	Ohms
Resistance	Fault Relay Post 85 to 86	90	Ohms
Resistance	Fuel Solenoid	10.0 - 10.6	Ohms
Resistance	Power windings across 11 & 22	0.1584-0.1840	ohms
Resistance	Rotor exciter small red wires (between any of the 3)	1.3 to 1.5	Ohm
Resistance	Rotor main winding across large white wires	9 -10	Ohm
Resistance	Rotor resistance	4.96-5.76	ohms
Resistance	Rotor resistance	6.30-7.32	ohms
Resistance	Rotor small red wires to large white wires	.7 to .6	Ohm
Resistance	Rotor winding (each winding)	5.9-6.0	Ohm's
Resistance	Starter Solenoid small post to ground	3.5 - 4.0	Ohms
Resistance	Stator Black to White	.30-.50	Ohm's
Resistance	Stator Green to Green	1.4 to 1.6	Ohm's
Resistance	Stator Red to Red	1.4 to 1.6	Ohm's
Resistance	Stator auxiliary winding	1.4 - 1.6	Ohm
Resistance	Stator exciter winding	15 - 17	Ohm

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	Capacity	Notes
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	SAE 5W-30 sintético	API SJ, SL o mejor	1.03 l	9 kW; no usar aditivos especiales
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 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.
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	Liquid Propane (LP) vapor withdrawn or pipeline Natural Gas			NG min 1000 BTU/cu ft (37.26 MJ/m3); LP min 2500 BTU/cu ft (93.15 MJ/m3); min LP tank size 250 gal (946 L) recommended if converting from NG
Fuel	Natural Gas or LP Vapor			Fuel pressure: NG 3.5-7 in WC (Evolution), 5-7 in WC (Nexus); LP 10-12 in WC
Other		Fluido detector de fugas de gas no corrosivo		Para comprobación de fugas en todos los puntos de conexión durante las pruebas y el mantenimiento normal.

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
1	Unused / open	1 is unused / open	Info
2	Generator failed to start	Generator failed to start.	Warning	See Problems C and D.
3	Generator failed after starting	Generator failed after starting.	Warning	See Generator Troubleshooting Section.
4	Generator over or under frequency	Generator over or under frequency.	Warning	See Generator Troubleshooting Section.
5	Transfer Switch did not transfer the load to the generator	Transfer Switch did not transfer the load to the generator.	Warning	Service required.
6	Transfer Switch did not transfer the load to the utility	Transfer Switch did not transfer the load to the utility.	Warning	Service required.
7	Controller error	Controller error.	Warning	Service required.
1100	Overcrank	Engine Cranks but will not Start (5 crank attempts)	Shutdown	Problem 17
1200	Overspeed	Prolonged over specified Hz for 3 seconds	Shutdown	Test 12
1205	Overspeed	Instantaneous over specified Hz for 0.1 second	Shutdown	Test 12
1207	Overspeed	Monitors zero cross timing of AVR; 150 ms of 4500 rpm or higher	Shutdown	Test 64 and Test 60
1300	Low Oil Pressure	Occurred while running; check oil level and pressure	Shutdown	Test 61
1400	High Temperature	Air flow impeded; check inlet/outlet for debris	Shutdown	Test 62
1501	RPM Sensor	Twin Cylinder+Running; RPM sensor loss	Shutdown	Test 50 and Test 64
1505	RPM Sensor	Twin Cylinder+Cranking; RPM sensor loss	Shutdown	If engine cranks, Test 64. If not crank, Problem 15.
1511	RPM Sensor	Single Cylinder+Running; RPM sensor loss	Shutdown	Test 50 and Test 64
1515	RPM Sensor	Single Cylinder+Cranking; RPM sensor loss	Shutdown	If engine cranks, Test 64. If not crank, Problem 15.
1600	Underspeed	Unit is overloaded, slowing engine speed, fuel supply low or throttle control problem	Shutdown	Problem 3, or Test 50, or Test 12
1800	Overvoltage	Prolonged over-voltage	Shutdown
1900	Undervoltage	Prolonged under-voltage; below 80% for 10+ seconds	Shutdown	Preliminary Output Voltage Test
1901	Undervoltage	Instantaneous under-voltage due to sudden loss of voltage	Shutdown	Preliminary Output Voltage Test
1902	Undervoltage	Both zero crosses missing; faulty excitation winding or zero cross circuit	Shutdown	Preliminary Output Voltage Test
1906	Undervoltage	Single zero cross missing; faulty excitation winding or zero cross circuit	Shutdown	Preliminary Output Voltage Test
2099	Wiring Error	Mis-wired; customer connection low voltage and high voltage wires crossed	Shutdown	Check customer connection in generator
2100	Overload Remove Load	Overloaded - Default; one or both CTs detecting overload	Shutdown	Remove Load
2299	Undervoltage Overload	Unit was overloaded and attempted to start with large load	Shutdown	Remove Load
2399	Stepper Overcurrent	Current flow in stepper coil(s) above specification	Shutdown	Test 12
2400	Fuse Problem	Missing or damaged 7.5 amp controller fuse	Shutdown	Test 44
2800	Aux Shutdown	External shut down circuit is open	Shutdown	Check continuity of harness and operation of switch(es). Repair/replace as needed.
BATTERY PROBLEM	Problema de batería	El LED amarillo se ilumina en cualquier estado	Warning	Contactar un IASD
CHARGER WARNING	Advertencia del cargador	El LED amarillo se ilumina en cualquier estado	Warning	Contactar un IASD
FUSE PROBLEM	Fuse Problem	Unit will not start in AUTO with utility loss. (Firmware 1.11 and older only.)	Shutdown	Check the 7.5 amp fuse. If blown, replace with an ATO 7.5 amp fuse. If intact, contact an IASD.
HIGH TEMPERATURE	High Temperature	Unit shuts down during operation.	Shutdown	Check ventilation around the generator, intake, exhaust, and rear of generator. If no obstructions are present, contact an IASD.
INSPECT BATTERY	Inspeccionar batería	El LED amarillo se ilumina en cualquier estado	Warning	Inspeccionar la batería; pulsar ENTER para desactivar
LOW BATTERY	Batería baja	El LED amarillo se ilumina en cualquier estado	Warning	Desactivar la alarma; comprobar batería en BATTERY MENU; si GOOD contactar un IASD, si CHECK BATTERY sustituir la batería
LOW OIL PRESSURE	Low Oil Pressure	Unit will not start in AUTO with utility loss.	Shutdown	Check oil level and add oil as needed. If oil level is correct, contact an IASD.
LOW VOLTS REMOVE LOAD	Low Volts	Unit will not start in AUTO with utility loss.	Shutdown	Clear alarm and remove household loads from the generator. Put in AUTO and restart.
MISWIRE	Miswire / Wiring Error	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
NOT ACTIVATED	Not Activated	Unit will not start in AUTO with utility loss.		Refer to 'Activation' in installation manual.
OVERCRANK	Overcrank	Unit will not start in AUTO with utility loss.	Shutdown	Check fuel line shutoff valve is ON. Clear alarm. Start the unit in MANUAL. If it does not start or runs rough, contact an IASD.
OVERLOAD REMOVE LOAD	Overload	Unit shuts down during operation.	Shutdown	Clear alarm and remove household loads from the generator. Put in AUTO and restart.
OVERSPEED	Overspeed	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
OVERVOLTAGE	Overvoltage	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
RPM SENSE LOSS	Pérdida de detección de rpm	La unidad se para e intenta volver a ponerse en marcha	Shutdown	Desactivar la alarma, retirar cargas, poner en AUTO y reanudar; si no arranca contactar un IASD
SERVICE A	Service A	Yellow LED illuminated in any state.	Warning	Perform SERVICE A maintenance. Press ENTER to clear.
SERVICE B	Service B	Yellow LED illuminated in any state.	Warning	Perform SERVICE B maintenance. Press ENTER to clear.
STEPPER OVERCURRENT	Stepper Overcurrent	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
UNDERSPEED	Underspeed	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
UNDERVOLTAGE	Undervoltage	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD.
WARNING	Low Battery	Battery less than 12.1 Volts for 60 seconds	Warning	Test 45

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 Magneto Flywheel Gap adjustment

Tools: 0.008-0.012 inch thickness gauge, screwdriver

Rotate flywheel until magnet under module.
Insert 0.008-0.012 inch non-metallic thickness gauge.
Loosen mounting screws.
Let magnet pull magneto against gauge.
Tighten screws.
Remove gauge by rotating flywheel.

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.

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.

Check and Adjust Valves adjustment

⚠ Automatic start-up. Disconnect utility power before working on unit.

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

Remove valve cover.
Loosen rocker jam nut.
Turn pivot ball stud to adjust clearance to 0.05-0.1mm (0.002-0.004 in).
Tighten jam nut to specified torque.
Recheck clearance.
Install new valve cover gasket and cover.

Conversion de carburant adjustment

⚠ Explosion et incendie. Le carburant et ses vapeurs sont extrêmement inflammables et explosifs.

Localiser le bouton orange de conversion (A).
Tourner le bouton vers la flèche indiquant la source de carburant jusqu'à l'arrêt.
Le bouton tourne sur 180° et glisse dans le corps du mélangeur pour le propane liquide.
Saisir la sélection du carburant (PL ou GN) sur l'automate de contrôle (Assistant d'installation ou menu EDIT > Fuel Selection).

Conversión de combustible adjustment

⚠ Explosiones e incendio: no se permiten fugas de combustible.

Ubique la perilla naranja de conversión de combustible (debajo del mezclador en 9 kW, sobre el mezclador en 11 kW–22 kW).
Gire la válvula hacia la marca de flecha de la fuente de combustible hasta que se detenga.
Introduzca la selección de combustible (LP/gas natural) en el controlador mediante el Asistente de instalación o el menú EDIT, 'Fuel Selection'.

Current Calibration adjustment

⚠ Electrocution. Lethal voltage may be present at CTs.

Tools: clamp-on ammeter

Connect load bank to output.
Place amp meter over circuit.
Start generator and warm up.
Apply rated load.
Select Current Calibration menu.
Adjust display to match amp meter.
Save calibration.
Repeat for CT2.

Réglage du jeu des soupapes adjustment

⚠ Laisser le moteur refroidir avant d'ajuster le jeu des soupapes.

Tools: Clé à douille, Clés de 8/10/13/14 mm, Jauge d'épaisseur

Amener le piston au PMS de sa course de compression (les deux soupapes fermées).
Retirer les fils des bougies d'allumage et les écarter.
Retirer les bougies.
Retirer les quatre vis du couvercle des soupapes et jeter le joint.
Desserrer le contre-écrou du culbuteur (clé de 10 mm pour 9-11 kW ou 13 mm pour 16-22 kW).
Tourner le pivot à rotule tout en vérifiant le jeu avec une jauge d'épaisseur.
Maintenir le pivot et serrer le contre-écrou selon les spécifications.
Vérifier de nouveau le jeu.
Installer un nouveau joint sur le couvercle des soupapes.
Installer le couvercle et serrer les attaches en tracé croisé au couple spécifié.
Installer les bougies d'allumage et serrer à 25 N.m (18 pi-lb).
Rebrancher le câble de bougie.
Répéter au besoin pour l'autre cylindre.

Vérification du jeu des soupapes adjustment

⚠ Le moteur doit être froid avant la vérification.

Tools: Clé à douille, Jauge d'épaisseur

Fermer la vanne de carburant et débrancher la batterie pour éviter un démarrage accidentel.
Retirer les fils des bougies d'allumage et les écarter.
Retirer les bougies d'allumage.
Amener le piston au point mort supérieur (PMS) de sa course de compression.

Battery Voltage Drop Test diagnostic

Tools: DMM

Remove T1 fuse.
Set DMM to DC voltage.
Connect leads to battery posts.
Set controller to MANUAL.
Measure voltage drop at test points V1-V4.
Compare to specs.

Check for Ignition Spark diagnostic

Tools: spark tester

Turn off fuel supply.
Remove spark plug leads.
Attach spark tester to engine cylinder head.
Attach spark plug lead to tester.
Set controller to MANUAL.
Crank engine and observe spark.

Compression Test diagnostic

Tools: compression gauge, jumper wire

Shut off fuel supply.
Remove both spark plugs.
Ground spark plug boot or Wire 18.
Open throttle wide open.
Insert compression gauge.
Crank engine until pressure stabilizes.
Record highest reading.
Repeat for other cylinder.

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	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
	ATS 3 connects to Generator position 6		9kW unit DC circuit; four wire cable (SJO16/4) between control panel and transfer switch
	ATS 4 connects to Generator position 3		9kW unit DC circuit
	ATS 5 connects to ATS 7 with provided diode; diode cathode connects to position 5		9kW unit DC circuit
	ATS 7 connects to Generator position 4		9kW unit DC circuit
	ATS 8 connects to Generator position 2		9kW unit DC circuit
	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.
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
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 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)
240 V c.a.	N1 et N2	JAUNE no 1 et no 2	Détectent les chutes et les hausses du réseau public.
240 VCA	N1 y N2	AMARILLO Núm. 1 y Núm. 2	Detección de desenganche y activación del servicio público

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 GH426 family

Part #	Description	Category
0E9371A	Air Filter	Air filter
0J8478	Air Filter	Air filter
74182	Hose Oil Drain	Hose
070185E	Oil Filter	Oil filter
070185F	Recommended Oil Filter	Oil filter
073590A	FUSE 5A X BUSS	Service part / kit
0D7178T	Control panel fuse	Service part / kit
0E7886C	CB 40A 2P 240V S BQ2 LB (9KW)	Service part / kit
0H3421S	26R Exide battery	Service part / kit
0K8184	1 in ball valve	Service part / kit
0K8752	1/2 in ball valve	Service part / kit
0K8754	3/4 in ball valve	Service part / kit
0L2844	1-1/4 in ball valve	Service part / kit
0L2845	1-1/2 in ball valve	Service part / kit
0L2846	2” ball valve	Service part / kit
10000004936	Manual de l’utilisateur pour les générateurs refroidis à l’air de 60 Hz	Service part / kit
10000029517	BADGE ADHESIVE GUARDIAN (9KW)	Service part / kit
73190	Drain, Oil FSTEX 7400-02-9909	Service part / kit
74121	Frame 9kW	Service part / kit
74122	Generator Head 9kW	Service part / kit
74123	Assy. Stator Bracket	Service part / kit
74124	Sol. Vib 1.50 OD x 1.00 .69 Stud	Service part / kit
74125	Assy, Shield Air 9kW	Service part / kit
74129	Hinge Slip Joint	Service part / kit
G006482-0	Scheduled Maintenance Kit	Service part / kit
0E9368	Spark Plug (RL87YC or equivalent)	Spark plug
0G0767A	Spark Plug (RC12YC or equivalent)	Spark plug
0G0767B	Spark Plug	Spark plug
RC12YC	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.

Common questions

What is the oil capacity of the Generac GH-426?

The Generac GH-426 engine has an oil capacity of 1.03 liters.

What is the displacement of the Generac GH-426?

The Generac GH-426 has a displacement of 0.426 liters.

Which generators use the Generac GH-426 engine?

The Generac GH-426 powers 1 generator set(s), including Generac G0070420.

How often should you change the oil in the Generac GH-426?

The Generac GH-426 oil change interval is every 200 hours.

What is a common problem with the Generac GH-426 engine?

A commonly reported issue on generators using the Generac GH-426 is: Unit will not start in AUTO with utility loss. Cause: Start delay countdown. Fix: If the start up delay is greater than expected, contact servicing dealer to adjust from 2 to 1500 seconds..