Generac — Fuel Regulator Adjustment (hard starting GV410 gaseous fueled product)
Adjustments
From a Generac service manual covering: 4077, 4079, 4109, 4389, 4390, 4456, 4674, 4675. Check it applies to your exact model before use.
Applies to: Generac 4077, Generac 4079, Generac 4109, Generac 4389, Generac 4456
Before you start
- Under no circumstances should this adjuster be completely removed.
- A new freeze plug part # D2529 MUST be reinstalled to retain the tamperproof status of the regulator.
Procedure
- Check for proper spark using a spark tester.
- Check for proper fuel supply to the regulator; 11 inches of water column should be available.
- Check valve lash; valves should be set between .002-.004.
- Verify the regulator is not stuck (manually choke the unit to start, then retry).
- Remove the freeze plug located directly above the inlet.
- Unscrew the threaded adjuster to achieve 5mm from the top of the adjuster screw to the top of the threaded casting.
- Start the generator a number of times until satisfied the condition is fixed.
- Reinstall a new freeze plug part # D2529 and mark an X across the freeze plug with a permanent marker.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Fuel supply to regulator: 11 inches of water column
- Valve lash: .002-.004
- Adjuster dimension: 5mm from top of adjuster screw to top of threaded casting
Full service-parts list: Generac 4077 →, Generac 4079 →, Generac 4109 →, Generac 4389 →, Generac 4456 →
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.