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Generac GV-220 Engine

The Generac GV-220 is a 1-cylinder naturally aspirated engine. It powers generator sets from Generac, including the 0940 and 0941.

Also known as: Generac GV-220

Cylinders

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

Engine specifications

Cylinders	1
Aspiration	naturally aspirated

Generator sets powered by this engine

Generac 0940Generac 0941

How to read your Generac engine serial & model number →

Common problems

Engine cranks but will not start
Cause: Fuel level low
Fix: Replenish fuel supply
No AC output
Cause: Short circuit on the AC output side
Fix: Locate and repair short circuit
Priming function does not work
Cause: Blown 7.5 amp fuse
Fix: Replace the fuse
Overvoltage condition and speed control system cannot reduce output voltage
Cause: Carburetor linkage sticking with throttle stuck partly open
Fix: Repair sticking throttle
Generator circuit breaker trips / no AC voltage
Cause: Short circuit on the AC output side
Fix: Locate and repair short circuit
Engine will not crank
Cause: Blown 7.5 amp fuse
Fix: Replace the fuse
Engine starts, accelerates, shuts down at 4500 rpm
Cause: Carburetor linkage sticking with throttle stuck open
Fix: Repair sticking throttle
Engine speed is maintained and no-load voltage is good. However, when load is applied output voltage drops
Cause: Carburetor linkage sticking with throttle partly open
Fix: Repair sticking throttle
Generator loses AC power then shuts down
Cause: Inverter overheat condition
Fix: Allow inverter to cool; check for cause of overheating
Engine starts then shuts down after a few seconds
Cause: Oil pressure switch defective or Wire 85 circuit fault
Fix: Replace oil pressure switch if it is defective or repair Wire 85 circuit as necessary
Engine starts hard and runs rough
Cause: Badly fouled spark plug
Fix: Clean and regap or replace spark plug as necessary
Engine speed and AC output voltage erratic under constant load. AC output does not turn off intermittently
Cause: Stepper Motor failure
Fix: Replace Stepper Motor
Engine does not accelerate when load is applied
Cause: Carburetor linkage sticking with throttle stuck closed
Fix: Repair sticking throttle
Generator doesn't pull full load
Cause: Carburetion problem
Fix: Adjust or repair carburetor or fuel system as necessary
Engine starts but Stepper Motor does not move. Shut down occurs after several seconds
Cause: Stator Timing winding is open
Fix: Repair/replace bad wire(s) TIM1/TIM2 or replace Stator

Compiled from service & troubleshooting documentation across every generator set that uses the Generac GV-220.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Paper element w/foam pre-cleaner		—	25 hr
Fuel filter			—	100 hr
Oil filter			—	50 hr
Oil	SAE 30 above 32 F (0 C); SAE 5W-20 or 5W-30 below 32 F (0 C); API SC, SD, SE, SF or SG	29.0	—	50 hr
Spark plug	Champion RC12YC (or equivalent); gap 0.030 inch (0.76mm)		RC12YC	100 hr	Amazon eBay $12.90 NAPA $11.52 FridayParts $19.99

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		or before each use
Oil filter	Change	8 hr		First service — first filter change
Air cleaner paper filter	Clean	25 hr	12 mo	whichever comes first
Air cleaner paper filter	Replace	25 hr	12 mo	Replace if too dirty
Paper air filter	Clean	25 hr		Clean or replace every 25 hours
Engine oil	Change	50 hr		First service — thereafter; more frequently under heavy load or high ambient temp
Engine oil and oil filter	Change	50 hr		First service — Thereafter every 50 operating hours.
Oil filter	Replace	50 hr		First service — thereafter
Valve clearance	Adjust	50 hr		First service — after first 50 hours of operation
Air intake screen	Clean	100 hr		Clean more often if necessary
Fuel filter	Replace	100 hr	12 mo	whichever occurs first
Spark arrestor	Clean	100 hr		Inspect and clean spark arrestor
Spark arrestor muffler	Inspect	100 hr
Spark plug	Clean	100 hr		clean and set gap 0.030 inch
Spark plug gap	Adjust	100 hr		Set gap to 0.030 inch (0.76mm).
Battery	Test		6 mo	Every six months check battery state of charge with an automotive battery hydrometer
Battery state of charge	Test		6 mo	every six months, by automotive service facility

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	Crankshaft end play	0.006-0.023	inch	Allowable
Clearance	Exhaust system clearance to combustible material	3	inches (76mm)	minimum
Clearance	Exhaust system extension past outer edge of vehicle	1	inch (25mm)	minimum
Clearance	Exhaust valve stem diameter design (GV-220)	0.273-0.274	inch (6.945-6.960mm)	design
Clearance	Exhaust valve stem diameter wear limit (GV-220)	0.272	inch (6.909mm) minimum	wear limit
Clearance	Fuel line clearance to exhaust system parts	2	inches	minimum
Clearance	Intake valve stem diameter design (GV-220)	0.274-0.275	inch (6.965-6.980mm)	design
Clearance	Intake valve stem diameter wear limit (GV-220)	0.273	inch (6.934mm) minimum	wear limit
Clearance	Oil pump tip clearance	0.0000-0.0010	inch	Measured on shaft in oil sump; wear limit 0.004 inch
Clearance	Oil ring end gap design (GV-220)	0.015-0.055	inch (0.38-1.40mm)	design
Clearance	Oil ring end gap wear limit (GV-220)	0.062	inch (1.60mm) max	wear limit
Clearance	Ring to groove side clearance (GV-220)	0.0004-0.0014	inch (0.012-0.034mm)
Clearance	Ring-to-groove side clearance	0.0004-0.0014	inch
Clearance	Second ring end gap design (GV-220)	0.006-0.016	inch (0.15-0.40mm)	design
Clearance	Second ring end gap wear limit (GV-220)	0.024	inch (0.60mm) max	wear limit
Clearance	Throttle lever stop tab to stop block gap	0.003	inch (0.08-0.5mm)	engine coasting to a stop
Clearance	Throttle linkage gap between stop tab and stop block	0.003	inch (0.08-0.5mm)	minimum gap for throttle linkage adjustment
Clearance	Top ring end gap design (GV-220)	0.005-0.016	inch (0.15-0.40mm)	design
Clearance	Top ring end gap wear limit (GV-220)	0.024	inch (0.60mm) max	wear limit
Clearance	Valve guide diameter design (GV-220)	0.237-0.2364	inch (6.02-6.005mm)	design
Clearance	Valve guide diameter wear limit (GV-220)	0.238	inch (6.045mm) max	wear limit
Clearance	Valve margin design (GV-220)	0.034-0.04	inch (0.87-1.13mm)	design
Clearance	Valve margin wear limit (GV-220)	0.020	inch (0.50mm) max	wear limit
Clearance	Valve seat width design (GV-220)	0.034-0.044	inch (0.87-1.13mm)	design
Clearance	Valve seat width wear limit (GV-220)	0.064	inch (1.63mm) max	wear limit
Gap	Oil ring end gap	0.015-0.055	inch	Ring pushed to 2.75 inch depth
Gap	Second compression ring end gap	0.006-0.016	inch	Ring pushed to 2.75 inch depth
Gap	Spark plug gap	0.030	inch (0.8mm / 0.76mm)
Gap	Top compression ring end gap	0.005-0.016	inch	Ring pushed to 2.75 inch depth
Other	Compression release lift measured at tappet	0.020-0.047	inch	Section 2.4; Part 8 lists 0.027-0.055 inch
Other	Engine oil capacity	950	mL (1 quart)
Other	Flexible fuel hose length	6	inches	at least 6 inches longer than needed
Other	Generator compartment clearance around generator	1	inch (2 inches recommended)	all sides and ceiling
Other	Generator fuel pickup tube shorter than vehicle engine pickup tube	2 to 3	inches	recommended
Other	Generator mounting bolts	3/8"-16		four hardened steel bolts Grade 5; at least 3 threads visible past lock nuts when tight
Other	Minimum air inlet opening (unrestricted)	40	square inches	divide by free air inlet area percentage for restricted openings
Other	Piston major diameter design (GV-220)	2.753-2.754	inch (69.939-69.959mm)	design
Other	Piston minor diameter design (GV-220)	2.747-2.748	inch (69.789-69.809mm)	design
Other	Recommended minimum LP gas flow rate for air-cooled Impact-34 plus series generators	67	cubic feet per hour
Other	Standard cylinder bore diameter (GV-220)	2.7560-2.7570	inches (70.000-70.025mm)
Other	Valve spring force to compress to 1.39 inch	19.8-21.8	lbs
Other	Valve spring free length	2.074	inch
Other	Valve spring free length (GV-220)	2.0741	inch (52.69mm)
Other	Wrist pin outside diameter (GV-220)	0.708-0.709	inch (17.989-18.000mm); wear limit 0.707 in (17.969mm) minimum
Pressure	Engine compression pressure	60	psi	Nominal, cold engine while cranking; minimum allowable 55 psi
Pressure	Fuel pump outlet pressure	2.0 to 3.5	psi
Pressure	LP fuel system leak test pressure	90	psi (620 kPa)	minimum; use soap and water or equivalent
Pressure	LP gas inlet pressure to lockoff/secondary regulator	11	inches water column	Optimum; do not exceed 14 inches water column
Pressure	LP gas pressure at gaseous fuel solenoid valve / secondary regulator	11	inches water column	optimum; do not exceed 14 inches water column
Pressure	LP gas pressure at outlet of secondary regulator	1	inch water column (negative)
Pressure	Low oil pressure switch actuation	approximately 5	psi
Pressure	Oil pressure relief valve opening	approximately 30	psi
Resistance	Battery charge winding resistance (66 to 55 / 77 to 55)	0.095-0.108	ohm
Resistance	Fuel pump coil	about 0.75 to 1.00	ohm
Resistance	Ignition coil primary	about 0.5 to 1.5	ohm
Resistance	Ignition coil secondary	16,000-17,000	ohm
Resistance	Stator battery charge 55-66	0.095-0.108	ohm
Resistance	Stator battery charge 55-77	0.095-0.108	ohm
Resistance	Stator power phase AC1-AC2	0.414 to 0.465	ohm
Resistance	Stator power phase SL1-SL2	0.414 to 0.465	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	Ambient	Capacity	Notes
Engine oil	SAE 30 (summer); SAE 5W-30 (winter); SAE 10W-30 acceptable summer substitute			950.0 mL (1 quart)	Do not use SAE 10W-40. Use no special additives.
Engine oil	SAE 30 (summer); acceptable substitute SAE 10W-30 (summer)			950.0 ml (about 1 quart)	DO NOT USE SAE 10W-40
Engine oil	SAE 30 above 32 F (0 C); SAE 5W-20 or 5W-30 below 32 F (0 C)	API Service SC, SD, SE, SF or SG			SAE 10W-30 acceptable substitute above 32 F; do not use SAE 10W-40. Part 2 gives capacities about 850 ml without filter and 946 ml with filter; Part 8 lists 620 ml and 870 ml.
Engine oil	SAE 5W30 (winter)			950.0 ml (about 1 quart)
Engine oil	SAE 30 (summer, above 32°F/0°C); SAE 10W-30 acceptable substitute; SAE 5W-20 or 5W-30 (winter, below 32°F/0°C)	API SC, SD, SE, SF or SG	above 0°C	29.0 fl oz / ml	Do not use SAE 10W-40 oil; use no special additives
Fuel	Clean, fresh unleaded regular gasoline				Leaded Regular acceptable if unleaded unavailable; gasohol not recommended, max 10 percent ethanol; do not use methanol.
Fuel	LP gas (propane/butane vapor withdrawal)				Impact-34 plus (LP unit); propane vaporizes to -20F(-29C), butane to 32F(0C)
Fuel	LP gas, vapor withdrawal				Do not use liquid withdrawal tank; primary regulator required.
Fuel	Unleaded gasoline (leaded regular acceptable substitute); no more than 10% ethanol; no methanol				Impact-36 plus (gasoline unit)
Fuel	Unleaded gasoline (leaded regular grade acceptable substitute)	Max 10% ethanol if alcohol present; no methanol			Unleaded reduces lead and carbon deposits; remove alcohol-containing gasoline during storage
Fuel	Unleaded regular gasoline (leaded regular acceptable if unleaded unavailable); gasohol not recommended, max 10% ethanol if used; LP or natural gas optional				Do not use gasoline containing methanol; do not mix oil with gasoline
Fuel	LP gas (propane, butane or mixture)		above -29°C		Vapor withdrawal type system only. Propane vaporizes as low as -20°F (-29°C); butane returns to liquid below about 32°F (0°C).

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 automatic choke adjustment

Tools: needle nose pliers, screwdriver

With solenoid not pulled in, check choke plate is about 1/8 inch from full open.
Bend tip of bi-metal with needle nose pliers if adjustment needed.
Loosen two choke solenoid retaining screws.
Slide solenoid in slotted holes to set plunger axial movement.
With choke valve closed, set plunger bottomed in solenoid coil.
Tighten two screws.

Adjust throttle linkage adjustment

⚠ Do not overbend spring clip; it may lose clamping force.

Tools: pliers

Start engine and immediately shut it down.
Observe throttle lever rotate counterclockwise as engine coasts to stop.
Compress spring clip so linkage rod slides freely.
Rotate throttle lever until gap between stop tab and stop block is 0.003 inch.
Release spring clip to lock adjustment.

Adjust valve clearance adjustment

⚠ Engine must be at room temperature.

Tools: feeler gauge, Allen wrench, crow's foot, torque wrench

Rotate crankshaft until piston is at TDC of compression stroke; both valves closed.
Loosen rocker arm jam nut.
Turn pivot ball stud with Allen wrench while checking clearance with feeler gauge.
Set intake clearance to 0.001-0.0022 inch.
Set exhaust clearance to 0.0018-0.003 inch.
Hold stud and tighten jam nut; recheck clearance.

Adjusting Throttle Linkage adjustment

⚠ Do not overbend the spring clip or the clip will lose its clamping force.

Tools: Pliers

Start generator, then shut down right away; observe throttle lever rotate counterclockwise.
Check for gap of 0.003 inch (0.08-0.5mm) between stop tab and stop block.
With pliers, lightly compress spring clip on carburetor lever arm to slide linkage rod freely.
Rotate throttle lever to set gap to 0.003 inch (0.08-0.5mm).
Release spring clip to secure adjustment.

Adjusting Valve Clearance adjustment

Tools: allen wrench, feeler gauge, crows foot torque wrench

Position engine at room temperature with piston at TDC of compression stroke, both valves closed
Loosen rocker arm jam nut
Use allen wrench to turn pivot ball stud while checking clearance with feeler gauge to 0.001-0.003 inch
Hold pivot ball stud with allen wrench and tighten jam nut to 65-85 inch-pounds with crows foot
Recheck valve clearance to make sure it did not change

Throttle Linkage Adjustment adjustment

⚠ Do not overbend the spring clip or it will lose its clamping force

Tools: pliers

Start generator, then shut it down right away and observe throttle lever rotate counterclockwise as engine coasts to stop
Verify gap of 0.003 inch (0.08-0.5mm) between stop tab on throttle lever arm and stop block on carburetor die casting
With pliers, lightly compress spring clip on carburetor lever arm to allow linkage rod to slide freely
Rotate throttle lever to adjust gap to 0.003 inch clearance
Release spring clip to secure adjustment

Check engine compression diagnostic

⚠ Full compression cannot be obtained at cranking speed due to compression release.

Tools: compression gauge

Remove spark plug.
Insert automotive compression gauge into spark plug hole.
Crank engine until pressure stops increasing.
Record highest reading as compression pressure.

Test DC link voltage diagnostic

⚠ Cap DC link wires for safety.

Tools: DVOM, jumper wire, wire nuts

Disconnect 2-wire and 9-wire cables from inverter.
Disconnect red-black-blue-green DC link wires from inverter; cap them.
On revision D or higher, jump pin 6 to pin 7 on 9-wire cable.
Turn CB1 ON and start generator; engine should run about 3300 rpm.
Set VOM to DC and measure red to blue; expect about 375 VDC.
Measure red to black and blue to black; expect about 187 VDC.

Test battery charge circuit diagnostic

Tools: VOM

Disconnect Wire 77 at battery charge rectifier.
Disconnect stator Wire 66 at battery charge rectifier.
Disconnect Wire 55.
Set VOM to Rx1 and zero meter.
Measure resistance across Wires 77 and 55, then 66 and 55.
Run engine and measure AC voltage at Wires 66 and 77 terminals.
Measure DC voltage between Wire 55 and frame ground.

Test stator windings with VOM diagnostic

⚠ Isolate stator leads before insulation resistance tests.

Tools: VOM

Disconnect and isolate all stator leads.
Set VOM to Rx1 scale and zero meter.
Measure AC1 to AC2; note resistance.
Measure SL1 to SL2; note resistance.
Measure PS1 to PS2; note resistance.
Measure TIM1 to TIM2; note resistance.

Testing Stator Windings diagnostic

⚠ Stator leads must be isolated from other components, especially circuit boards, before testing

Tools: VOM (Volt-Ohm-Milliammeter)

Disconnect and isolate all stator leads
Set VOM to Rx1 scale and zero meter
Test power phase windings AC1-AC2 and SL1-SL2 for resistance
Test power supply winding PS1-PS2 for resistance
Test timing winding TIM1-TIM2 for resistance
Test for short-to-ground using Rx10,000 or Rx1K scale; reading should be infinity
Test for shorts between windings by connecting between different winding leads; reading should be infinity

Change Engine Oil maintenance

⚠ DO NOT FILL ABOVE FULL MARK

Warm up engine at least five minutes, then shut down
Clean area around oil drain plug and remove drain plug; drain oil completely
Install and tighten drain plug
Remove oil dipstick and fill crankcase with recommended oil to FULL mark
Install and tighten dipstick cap before operating engine

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
		55	Black	Connects to grounding terminal
		66	Brown	Connects to Battery Charge Rectifier BCR
		77	Brown	Connects to Battery Charge Rectifier BCR
		DC output leads	+DC (Red), -DC (Blue), Return (Black), Ground (Green)	Route from generator DC output leads through approved flexible conduit to terminal block in DC junction box on inverter
		PS1	Red	Connects to J1
		PS2	Black	Connects to J1
		Remote panel receptacle	Wire #0 (Ground), Wire #14 (Engine run signal), Wire #17 (Crank), Wire #18 (Stop)	Optional remote-mounted start/stop panel
		TIM1	Orange	Connects to A6060 circuit board J5 Pin 1
		TIM2	Grey	Connects to A6060 circuit board J5 Pin 2
	1-Phase	AC1	Grey	Connects to CB1A
	1-Phase	AC2	Yellow	Connects to BR1
	1-Phase	SL1	Orange	Connects to CB1B
	1-Phase	SL2	Brown	Connects to BR3
12		Battery cables	Positive to large lug on starter contactor; Negative to frame ground	Cable size by length: 0-10 ft (0-3m): No.2; 11-15 ft (3.4-4.5m): 0; 16-20 ft (4.5-6m): 000. For warm weather use No.2 cable up to 20 feet.
120	single	AC output	T1 (Black), T2 (White), Green ground	From AC output junction box on inverter to double-pole double-throw transfer switch or approved isolation receptacle

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

Common questions

Which generators use the Generac GV-220 engine?

The Generac GV-220 powers 2 generator set(s), including Generac 0940, Generac 0941.

How often should you change the oil in the Generac GV-220?

The Generac GV-220 oil change interval is every 50 hours.

What is a common problem with the Generac GV-220 engine?

A commonly reported issue on generators using the Generac GV-220 is: Engine cranks but will not start. Cause: Fuel level low. Fix: Replenish fuel supply.