Cummins/Onan — Cleaning the Carburetor and Combustion Chambers with Onan "4C"
Maintenance · Carburetor / combustion chambers
From a Cummins/Onan owner's manual covering: E124V, E125, E140, Miller P216, Miller P218, Miller P220, Miller P224, P218, P220, P248. Check it applies to your exact model before use.
Applies to: Cummins/Onan E124V, Cummins/Onan E125, Cummins/Onan E140, Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAC
Before you start
- Chemical combustion chamber cleaners are caustic, toxic and flammable; flush skin or eye contact with water 15 minutes
Procedure
- Park the vehicle outside where fumes and soot can disperse.
- Run the genset until up to normal operating temperature.
- Stop the genset and remove the air filter for access.
- Restart and spray "4C" into the carburetor throat; flood engine to stall just before can empties.
- Let the genset sit 15 minutes.
- Restart and load nearly to full power for about five minutes.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan E124V →, Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAC →
Source: Cummins/Onan owner's 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.