Cummins/Onan 4MCCK / 605MCCK — Fuel Pump Testing
Testing & diagnosis
For the Cummins/Onan 4MCCK / 605MCCK, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 605MCCK, Cummins/Onan MCCK, Cummins/Onan MCCK engine
Procedure
- Disconnect the pump outlet line and install a pressure gauge.
- Operate the priming lever a few times while watching the pressure; it should not drop off rapidly.
- Run the engine at governed speed on the fuel remaining in the carburetor and measure the fuel pump pressure.
- Pressure should be between 2 and 3 psi with the gauge held 16 inches above the fuel pump.
Tools required
- pressure gauge or manometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Pressure should be between 2 and 3 psi
Full service-parts list: Cummins/Onan 605MCCK →, Cummins/Onan MCCK →
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.