Cummins/Onan 3100 series — Adjusting Carburetor Power Valve
Adjustments
For the Cummins/Onan 3100 series, from the Cummins/Onan service manual.
Applies to: Cummins/Onan GGKD
Procedure
- Install a 0-30 psi gauge on the intake manifold.
- Install a pyrometer in the 1/8 inch pipe tapped hole of the exhaust manifold ahead of the turbocharger.
- Install an oxygen meter exhaust gas pickup in a 1/8 inch pipe tapped hole of the exhaust elbow.
- With the genset at full load, adjust the power valve for the lowest possible exhaust temperature while observing O2.
- Turn the power valve closed (toward L) until the engine starts losing RPM.
- Then turn the power valve open (toward R) until the exhaust temperature reaches the lowest reading.
- LP vapor only: if O2 cannot be set with the power valve, set power valve to mid-point and use the course adjustment valve.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- EGT max 1375°F (746°C) ahead of turbocharger
- Exhaust O2 5% ±1%
- Intake manifold pressure 15 psi max
Full service-parts list: Cummins/Onan GGKD →
Source: Cummins/Onan 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.