Cummins/Onan — Carburetor Service and Installation
Repair & overhaul
From a Cummins/Onan service manual covering: P4500, P5000E, P5000e. Check it applies to your exact model before use.
Applies to: Cummins/Onan P4500
Before you start
- Close the fuel shutoff valve and drain the carburetor before servicing the carburetor.
- Service must only be performed by a Cummins Onan certified technician.
Procedure
- Disassemble the carburetor for inspection and service.
- Clean the internal passages and orifices of the carburetor body with compressed air.
- Check the pilot screw head for wear or damage; initial opening is 1-5/8 turns out.
- Check the float valve for weak spring and general wear; check float for smooth movement.
- Clean the drain screw, main nozzle, and jet thoroughly with compressed air.
- Inspect the fuel cut-off solenoid; make sure the O-ring is seated.
- Reinstall carburetor, governor assembly, choke assembly, and air cleaner; open the fuel shut-off valve.
- Check the drain screw and set bolt for leaks and repair if necessary.
Tools required
- Compressed air Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Pilot screw initial opening 1-5/8 turns out
Full service-parts list: Cummins/Onan P4500 →
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.