Cummins/Onan 4.0BGEFA261 OOL / 4.0BGEFA26100L — Cleaning the Carburetor and Combustion Chambers with Onan "4C"
Maintenance
For the Cummins/Onan 4.0BGEFA261 OOL / 4.0BGEFA26100L, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan EM (SN5782U1G2RA) engine
Before you start
- Chemical combustion chamber cleaners are caustic, toxic and flammable and can cause severe personal injury; wear safety goggles and rubber gloves and keep face out of line of cleaner fluid that may spit back.
- If skin or eye contact occurs, flush with water for 15 minutes and seek medical attention.
- Do not smoke while performing this operation.
Procedure
- Always dock the pontoon boat outside where fumes and soot can disperse.
- Run the genset until it is up to normal operating temperature.
- Stop the genset and remove the air filter for access to the carburetor throat and choke plate.
- Restart the genset and spray "4C" into the carburetor throat, washing down the choke plate and throat as fast as possible without stalling.
- Just before the can empties, flood the engine so that it stalls.
- Let the genset sit for 15 minutes to allow the cleaner to soften carbon deposits.
- Restart the genset and load it nearly to full power; run about five minutes to expel loosened carbon.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Let genset sit 15 minutes
- Run about five minutes under near-full load
Source: Cummins/Onan operator'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.