IMPORTANT: Read the owner's manual thoroughly and understand all instructions, cautions, and warnings before servicing this equipment. If any section of the manual is not understood, contact an Independent Authorized Service Dealer (IASD), contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or visit Generac.com with any questions or concerns.

Servicing the spark plugs

Sections

• Environment
• Before you begin
• Next Generation Series spark plug maintenance
• Guardian Series spark plug maintenance

Environment

This article applies to:

• Generac Next Generation Series 10–28 kW air-cooled home standby generators.
• Generac Guardian Series 10–26 kW air-cooled home standby generators (2017 to present).

Generator owners should always reference the owner's manual for maintenance tasks and model-specific specifications. See Where can I find a user manual or other documentation for my home standby generator? for information on locating the correct manual.

Before you begin

Generator owners should reference these articles before servicing the spark plugs:

• Maintenance schedule: Where Can I Find the Maintenance Schedule for My Generac Home Standby Generator?
• Maintenance safety: What Safety Precautions Should I Take When Performing Maintenance on My Generator?
• Maintenance kits: Where can I find a maintenance kit for my Generac generator?
• Authorized service dealers: How Can I Find a Generac Service Dealer in My Area?

IMPORTANT: Before performing spark plug maintenance, follow the procedures specified in the generator's owner's manual. A home standby generator can start automatically without warning. Do not rely solely on pressing the OFF button to make the generator safe for maintenance. Refer to the maintenance safety article linked above for additional precautions.

Note: Generator owners who are unfamiliar with spark plug maintenance or do not feel comfortable performing this procedure should contact an Independent Authorized Service Dealer (IASD) for assistance.

Next Generation Series spark plug maintenance

Spark plug specifications

The same recommended spark plug part number is used across the Next Generation Series models listed below. Consult the generator's owner's manual to confirm the applicable spark plug specifications.

Model	10 kW	14/18 kW	22–28 kW
Engine type	G-Force™ 400 Series	G-Force™ 800 Series	G-Force™ 1000 Series
Recommended spark plug	A0003637864	A0003637864	A0003637864
Spark plug gap	0.020 in (0.508 mm)	0.020 in (0.508 mm)	0.020 in (0.508 mm)

Spark plug location and service

Removing the plastic air filter cover may be necessary to access the rear spark plug. The air filter cover has been removed in the image below.

Front spark plug:

Rear spark plug:

To inspect the spark plug gaps and replace the spark plugs:

1. Follow the shutdown and automatic-start prevention procedures in the generator's owner's manual. Verify that the generator is OFF and the engine is cool before lifting the lid and removing the front panel.
2. Clean the area around the base of each spark plug to prevent dirt and debris from entering the engine.

Note: Clean and re-gap spark plugs in emergency situations only. Otherwise, replace the spark plugs.

3. Remove the spark plugs and inspect the spark plug gaps using a wire feeler gauge. Replace the spark plugs if the gaps are outside the specified range. Refer to the spark plug specifications table above for the recommended spark plug part number and gap.

Note: Check the spark plug gap on new spark plugs before installation.

4. Install the spark plugs and tighten to 18.4 ft-lbs (25 Nm), or the torque specified in the generator's owner's manual.
5. Reinstall any covers or panels removed during maintenance.
6. After maintenance is complete, follow the applicable power restoration procedure in the generator's owner's manual. Return the generator to AUTO mode only after completing the required restoration steps.

Guardian Series spark plug maintenance

Spark plug specifications

Spark plug part numbers and gap specifications vary by Guardian Series generator model. Refer to the specifications below and confirm the correct information in the generator's owner's manual.

Model	10 kW	14/18 kW	20–26 kW
Recommended spark plug	0G0767B	0G0767A	0G0767A
Spark plug gap	0.020 in (0.508 mm)	0.040 in (1.02 mm)	0.040 in (1.02 mm)

Spark plug location and service

For air-cooled Guardian Series two-cylinder (V-twin) models, the spark plugs are located as shown below:

For air-cooled Guardian Series single-cylinder models, the spark plug is located as shown below:

To inspect the spark plug gaps and replace the spark plugs:

1. Follow the shutdown and automatic-start prevention procedures in the generator's owner's manual. Verify that the generator is OFF and the engine is cool before lifting the lid and removing the front panel.
2. Clean the area around the base of each spark plug to prevent dirt and debris from entering the engine.
3. Remove and inspect the spark plugs. Use a 3/8-inch ratchet with a 5/8-inch spark plug socket to remove each spark plug. Check the condition of each plug and replace it if worn or questionable. Refer to the spark plug specifications table above for the recommended spark plug part number and gap.
4. If cleaning a spark plug is necessary in an emergency, clean it by scraping or washing with a wire brush and commercial solvent. Do not blast spark plugs to clean them.

Note: Clean spark plugs in emergency situations only. Otherwise, replace the spark plugs.

5. Inspect each spark plug gap using a wire feeler gauge. Replace the spark plug if the gap is outside the specified range. Refer to the Specifications section of the generator's owner's manual for model-specific engine information.

Note: Check the spark plug gap on new spark plugs before installation.

6. Install the spark plugs and tighten to 18.4 ft-lbs (25 Nm), or the torque specified in the generator's owner's manual.
7. Reinstall any covers or panels removed during maintenance.
8. After maintenance is complete, follow the applicable power restoration procedure in the generator's owner's manual. Return the generator to AUTO mode only after completing the required restoration steps.