Lou @RVHabit

Replacing A Fuel Filter On A Cummins Onan RV Generator - RV Maintenance

General maintenance is imperative to keep the Onan RV generator running smoothly. I change the oil every year or 150 hours, whichever comes first. I also do a Seafoam treatment twice a year. If you don't know what that is I will put a link below to the article and video I did on this. It is worth a look and keeps the generator running great. Often forgotten is the fuel filter. After just two years my RV generator fuel filter typically looks like the one in the photo.

I worry that the rust that inevitably forms will either prevent it from being removed or worse, begin to leak. The fuel filter is an inexpensive part. I change mine every two years to keep things running well and in good condition. My RV has a Cummins Onan RV QG 4000 Generator. I only use genuine Cummins Onan Green Label Parts and never any "will fit" replacements.

I also use just a little Permatex High-Temperature Thread Sealant at the base of the threads when installing the new fuel filter. The install is actually one of the easier things to do on the Onan RV Generator. There are only a few steps and the fuel filter is easily accessible from underneath the RV.

First, remove the fuel line from the fuel filter. The fuel line needs to be plugged or pinched off as gravity will allow the fuel line to leak gasoline. A rubber grommet is easily removed from the oval hole which then reveals the fuel filter. I use a deep well 9/16" socket which perfectly fits on the end of the fuel filter. Then slowly turning counterclockwise the old filter will simply unscrew from the fuel pump. The fuel filter is full of gasoline so watching your eyes when removing it is a must.

I put a small amount of Permatex High-Temperature Thread Sealant at the base of the threads on the new Fuel Filter. My RV uses a Cummins Onan Fuel Filter Part# 0149-2457. You should check your RV's manual for the exact part numbers needed for your specific Onan generator. The new fuel filter will just fit inside the oval hole allowing it to be connected to the fuel pump. Take your time and only do this by hand to make sure the threads go on straight and not crossed.

After getting the fuel filter started I tighten with a socket. I have never found a torque spec so I tighten it firmly making sure to not overtighten. I replace the rubber grommet and fuel line and I'm done. It takes under fifteen minutes and gives me peace of mind. I now don't worry about some type of failure due to age or rust.

Watch the video below to see how I change the fuel filter on a Cummins Onan RV Generator