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Honda iGX390 Engine

The Honda iGX390 is a 0.39 L engine rated at 3600 rpm. It powers generator sets from Honda, including the EB5000, EB6500 and EM5000SX. It holds 1.1 L (0.3 gal) of oil.

Also known as: Honda iGX390

0.389 L

Displacement

3600 rpm

Rated speed

1.1 L

Oil capacity

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

Engine specifications

Oil capacity	1.1 L
Displacement	0.389 L
Rated speed	3600 rpm

Generator sets powered by this engine

Honda EB5000Honda EB6500 Honda EM5000SX

How to read your Honda engine serial & model number →

Common problems

Engine will not start
Cause: Fuel valve lever OFF
Fix: Turn lever ON (see page 44)
No power at the AC receptacles
Cause: AC circuit breaker left in the OFF position after starting
Fix: Switch AC circuit breaker ON (see page 53)
Engine lacks power
Cause: Air filter restricted
Fix: Clean or replace air filter (see pages 41, 67)
No power at the DC terminals
Cause: DC circuit protector OFF
Fix: Turn DC circuit protector ON (see page 32)
Engine automatically stop and the FAULT/CO SENSOR LIFE indicator flashing
Cause: CO sensor malfunction
Fix: If the engine cannot be started and the CO ALARM indicator flashes, even if the location of the generator has changed, there may be a CO-MINDER malfunction. Consult an authorized Honda Power Equipment dealer
When the engine will hot start
Fix: 1. Is the engine switch on? 2. Does the oil alert lamp flash when the starter is pulled? 3. Is there enough fuel? 4. Are all loads disconnected 5. Is there a spark at the spark plug? 6. Is gasoline reaching the carburetor? To check, place a suitable valve on and loosen the drain screw. Fuel should flow out freely.
No electricity at the AC receptacles — Is the AC circuit breaker ON?
Cause: AC circuit breaker OFF
Fix: Turn the AC circuit breaker ON.
No electricity at the AC receptacles — Check the electrical appliance or equipment for any defects (no defects found)
Fix: Take the generator to an authorized Honda generator dealer.
No electricity at the AC receptacles — Check the electrical appliance or equipment for any defects (defects found)
Cause: Defective electrical appliance or equipment
Fix: Replace the electrical appliance or equipment; take the electrical appliance or equipment to an electrical shop for repair.
FAULT/CO SENSOR LIFE indicator flashing when running the engine
Cause: CO sensor may reach the end of its useful lifespan
Engine will not start — Is there fuel in the tank?
Cause: No fuel in the tank
Fix: Refill the fuel tank.
Engine will not start — Is there enough oil in the engine?
Cause: Not enough oil in the engine
Fix: Add the recommended oil.
Engine will not start — Is the spark plug in good condition?
Cause: Spark plug gap incorrect or spark plug wet
Fix: Readjust gap and dry the spark plug; replace it if necessary.
Engine will not start — Is the fuel reaching the carburetor?
Cause: Fuel not reaching the carburetor; fuel sediment cup clogged
Fix: Clean the fuel sediment cup; turn off the engine switch and loosen the drain screw (see page 46); turn the fuel valve to ON — fuel should flow from the drain when the fuel valve is turned ON.
Engine will not start — If the engine still does not start
Fix: Take the generator to an authorized Honda generator dealer.

Compiled from service & troubleshooting documentation across every generator set that uses the Honda iGX390.

Service intervals

Item	Action	Hours	Months	Notes
Engine oil	Change	300 hr	12 mo	First service — First month or 20 hrs
Air cleaner	Clean	100 hr	6 mo	Service more frequently when used in dusty areas (1)
Sediment cup	Clean	100 hr	6 mo	Page 58
Spark arrester	Clean	300 hr	12 mo	Must be serviced every 100 hours to maintain its efficiency
Spark plug	Adjust	300 hr	12 mo	Readjust — every 6 months or 100 Hrs
Fuel tank and filter	Clean	300 hr	12 mo	(2)
Fuel tank and strainer	Clean	300 hr	12 mo	(2) Every year or 300 Hrs
Spark plug	Replace	300 hr	12 mo	Every year or 300 Hrs (page 69)
Valve clearance	Adjust	300 hr	12 mo	Check-adjust every year or 300 Hrs; by servicing dealer (2)
Combustion chamber	Clean	1000 hr		After every 1,000 hrs
Canister	Check		24 mo	Every 2 years (2)
Charge tube	Check		24 mo	Every 2 years (2)
Fuel line	Replace		24 mo	Every 2 years (Replace if necessary)
Fuel tube	Check		24 mo	Every 2 years (replace if necessary) (2)
GFCI receptacle	Test		1 mo	Once each month; test before each use if generator is stored outside unprotected
Purge tube	Check		24 mo	Every 2 years (2)

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	Float height	13.2	mm
Gap	Ignition coil air gap	0.2 – 0.6	mm
Gap	Spark plug electrode gap	0.028–0.031 in (0.7–0.8 mm)	mm
Gap	Spark plug gap	0.028 - 0.031	in
Gap	Spark plug gap	0.028-0.031	in
Gap	Spark plug gap	0.028–0.031	in (0.7–0.8 mm)
Gap	Spark plug gap	0.7 - 0.8	mm
Gap	Spark plug gap	0.70 – 0.80	mm
Gap	Spark plug gap	0.70-0.80	mm
Other	Compression ratio	8.2:1
Other	Crank duration	3-3-4-5	sec	per automatic attempt sequence
Other	Enclosure dimensions	85x58x33	mm
Other	Length of cable	2	m
Other	Max. Standby Current	9.8	mA @ 12 V
Other	Number of attempts	4		automatic starting attempts
Other	Pause between each automatic attempt	10	sec
Other	Spark plug installation (new plug)	1/2	turn after seating to compress washer	new spark plug
Other	Spark plug installation (reused plug)	1/8 - 1/4	turn after seating to compress washer	reinstalling a used spark plug
Pressure	Cylinder compression	1.29	MPa	at 1,400 min-1 (rpm)
Pressure	Cylinder compression	1.31	MPa	at 1,400 min-1 (rpm)
Resistance	CT sensor resistance	18 ±2	Ω
Resistance	Spark plug cap resistance	7.5 – 12.5	kΩ
Speed	Auto Throttle idle speed	2,300 ± 100	min-1 (rpm)
Speed	Engine speed	3,600	rpm
Speed	Engine speed protection limit (DAVR self-diagnosis)	4140	rpm	abnormal voltage/speed sustained longer than 3 seconds
Speed	Maximum engine speed	3,600 ± 100	min-1 (rpm)
Temperature	Operating Temperature Range	-30 to +70	°C
Torque	Air cleaner case bolt	5.4	N·m
Torque	Carburetor mount nut	8.5	N·m
Torque	Connecting rod special bolt	14	N·m
Torque	Control panel mount bolt	27	N·m
Torque	Crankcase cover bolt	24	N·m
Torque	Cylinder head bolt	35	N·m
Torque	Engine mount nut	34	N·m
Torque	Exhaust pipe nut	24	N·m
Torque	Fan cover stud bolt	23	N·m
Torque	Fan cover stud bolt mounting nut	40	N·m
Torque	Flywheel special nut	128	N·m
Torque	Flywheel special nut	170	N·m
Torque	Front housing bolt	24	N·m
Torque	Fuel meter screw	4	N·m
Torque	Fuel valve nut	23	N·m
Torque	Generator cooling fan screw	4.8	N·m
Torque	Handle installation	17–22 lbf·ft (24–29 N·m, 2.4–3.0 kgf·m)	N·m
Torque	Handle installation flange bolts	19.5 lbf·ft (26.5 N·m, 2.7 kgf·m)	lbf·ft
Torque	Hanger kit flange bolts	19.5 lbf·ft (26.5 N·m, 2.7 kgf·m)	lbf·ft
Torque	Hanger kit installation	17–22 lbf·ft (24–29 N·m, 2.4–3.0 kgf·m)	N·m
Torque	Oil drain bolt	22.5	N·m
Torque	Oil drain plug (12×15 mm)	16.3 lbf·ft (22.1 N·m, 2.25 kgf·m)	lbf·ft
Torque	Oil drain plug (12×15 mm)	16.6 lbf·ft (22.5 N·m, 2.25 kgf·m)	N·m
Torque	Rear housing cover bolt	9.8	N·m
Torque	Rocker arm pivot adjusting nut	10	N·m
Torque	Rocker arm pivot special bolt	24	N·m
Torque	Rotor bolt	44	N·m
Torque	Rubber mount nut	24	N·m
Torque	Spark plug	13.0 lbf·ft (17.7 N·m, 1.8 kgf·m)	lbf·ft
Torque	Spark plug	13.3 lbf·ft (18 N·m, 1.8 kgf·m)	N·m
Torque	Spark plug	18	N·m
Torque	Spark plug tightening (new plug)	1/2 turn after the spark plug seats	turn	new spark plug
Torque	Spark plug tightening (used plug)	1/8 - 1/4 turn after the spark plug seats	turn	reinstalling a used spark plug

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	SAE 10W-30	API service category SJ or later (or equivalent)	1.1 L	Maximum oil capacity 1.2 US qt (1.1 L); 4-stroke automotive detergent oil; other viscosities per ambient temperature chart
Engine oil	SAE 10W-30 (other viscosities per ambient temperature chart)	API service classification SJ or higher	1.1 L	Non detergent and 2-stroke oils are not recommended
Fuel	Regular unleaded gasoline	pump octane rating 86 or higher
Fuel	Regular unleaded gasoline, pump octane rating 86 or higher	No more than 10% ethanol (E10) or 5% methanol by volume	23.5 L	Fuel tank capacity 6.21 US gal (23.5 L)
Fuel	Unleaded gasoline, pump octane number (R+M)/2 of 86 or higher, or research octane number of 91 or higher		17.0 lit	Fuel tank capacity 17.0 lit (4.5 US gal); do not fill above UPPER LEVEL line; max 10% ethanol; never use methanol above 5%; never use stale or contaminated gasoline or an oil/gasoline mixture
Fuel	Unleaded gasoline, pump octane rating 86 or higher		17.0 L	Fuel tank capacity 17.0 L (4.50 US gal, 3.74 Imp gal); up to 10% ethanol, 5% methanol, or 15% MTBE
Fuel	unleaded gasoline, pump octane rating 86 or higher		17.0 L	Do not fill above the shoulder of the fuel strainer; oxygenated fuels allowed up to 10% ethanol, 15% MTBE, 5% methanol by volume
Grease	Marine grease	water resistant urea based grease
Grease	Multi-purpose grease	NLGI #2 or equivalent		Lithium based multi-purpose grease
Other	Automatic transmission fluid	ATF

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

Procedures

Setting up 10 sec start delay adjustment

⚠ 10 sec start delay is used in combination with an ATS panel to prevent multiple short start-stop commands coming from the ATS panel while the mains is unstable during blackout.

Open the controller cover and locate the red dip switch (S-DELAY).
Use your finger to move the dip switch 1 to ON position.
Replace the cover and tighten screws.

GFCI Operation Check (System ①) diagnostic

⚠ A faulty GFCI system will not provide proper protection against electric shock.

⚠ If the GFCI system fails the test, the generator must be repaired by an authorized Honda servicing dealer before use.

Unplug all tools and appliances from the generator.
Start the engine.
Turn OFF the Auto Throttle switch.
Turn the AC circuit breaker to the ON position.
Press the TEST button: the RESET button should pop out and the AC circuit breaker should switch to OFF.
Press the RESET button: it should stay in, flush with its base plate.
With the RESET button in and the engine running, turn the AC circuit breaker to ON; it should remain ON.

GFCI Operation Check (System ②) diagnostic

⚠ If the red indicator starts to blink continuously, contact an authorized Honda generator dealer.

Unplug all tools and appliances from the generator.
Start the engine.
Turn OFF the Auto Throttle switch.
Turn the AC circuit breaker to the ON position; the green indicator should light continuously.
Press the TEST button: the RESET button will pop out and the green indicator will go off.
Press the RESET button: the green indicator will light continuously.

2 Wheel Kit Installation installation

Install the two wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.
Install the two stands using four bolts and nuts.
Install right and left handles on the generator upper frame using brackets and six bolts.

2-Wheel Kit Installation installation

Install the two wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.
Install the two stands using four bolts and nuts.
Install right and left handles on the generator upper frame using brackets and six bolts.

4 Wheel Kit Installation installation

⚠ Install the shaft with the wheel stopper facing the engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

4-Wheel Kit Installation installation

⚠ Install the shaft with wheel stopper facing engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

4-Wheel Kit Installation (optional parts) installation

⚠ Install the shaft with wheel stopper facing engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

Handle Installation installation

⚠ Do not add fuel or oil before tipping the generator.

Tools: 12 mm wrench (2), pliers

Install the handle holder assembly on the generator upper frame using the 8×18 mm flange bolts.
Install the handle assembly on the upper frame pipe using 8×16 mm flange bolts, handle bush A, handle bush B, and handle lower bracket.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).
Check that the handle folds smoothly and does not hang down by its own weight.

Hanger Kit Installation installation

Tools: 12 mm wrench (2)

Position the hanger at the generator's balance point.
Fit the end tabs of the hanger through the bracket slots.
Bolt the brackets to the hanger and tighten securely.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).

Wheel Kit Installation installation

Tools: 12 mm wrench (2), pliers

Install the two stands on the under frame using four 8×16 mm flange bolts.
Install the two wheels on the axle shaft using the washers and split pins; bend the pins.
Install the axle assembly using four 8×16 mm flange bolts and 8 mm flange nuts.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).

Air Cleaner Check/Cleaning maintenance

⚠ Excess oil will restrict air flow and may cause engine to smoke at startup.

⚠ Operating without element or loose element allows dirt to enter engine.

Remove air cleaner case lid springs and unhook tabs.
Remove air cleaner cover and element.
Check element and replace if damaged.
Clean element in warm soapy water or non-flammable solvent, dry thoroughly.
Dip filter in clean engine oil, squeeze out excess oil.
Install air cleaner in reverse order of removal.

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
120 V		Voltage selector switch in "120V ONLY" position		Only the 120V receptacles can be used; do not use the 120/240V receptacle in this position; rated power available at the 30A 120V twist lock receptacle
120/240 V		Voltage selector switch in "120/240V" position		The 120V and 120/240V receptacles can be used simultaneously; required if a 240V appliance is connected to the 4-prong 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

What is the oil capacity of the Honda iGX390?

The Honda iGX390 engine has an oil capacity of 1.1 liters.

What is the displacement of the Honda iGX390?

The Honda iGX390 has a displacement of 0.389 liters.

Which generators use the Honda iGX390 engine?

The Honda iGX390 powers 3 generator set(s), including Honda EB5000, Honda EB6500, Honda EM5000SX.

What is a common problem with the Honda iGX390 engine?

A commonly reported issue on generators using the Honda iGX390 is: Engine will not start. Cause: Fuel valve lever OFF. Fix: Turn lever ON (see page 44).