Fuel cleaner/additive for Onan generator

I am old so I still use Seafoam in my engine and genset. I disconnect the line from the main fuel tank and add 8 ounces of Seafoam in a gallon of gas and run the genset under load (2 A/C's running) it is also a good way to see how much gas your genset burns in a hr. Also I add some to the crank case before I change my oil in the genset. I was amazed at how much caked carbon came out of the crank case the first time I tried it. I do this about every 4 or 5 years. The generator runs very smooth after treatment. The genset is 24 years old and never had the carb rebuilt or any work on the engine it self. I not sure why people run it dry before winter storage if you exercise it once a month under load per Mfg instructions.

I use Lucas

Any fuel system cleaner that is good for the big gas engine will also be good for the little one.

SeaFaom is NOT a good cleaner; it was designed as a fuel stabilizer.

Gumout and Berrymans B12 Chemtool are the best cleaners on the market.
Assuming that your big engine is fuel injected, Techron would be good for routine use too.

It is best to use fuel system cleaners with half a tank of gas during a trip when you can run the gen too......because putting the right amount into a tank that is 40 gallons or more can get to be kind of expensive.

Thanks for the replies. I do use my generator a lot and have always run it under load (a/c or microwave running) all year long as well as driving the RV during the winter season for about 30 minutes just to keep things lubed and moving. Have had no issues with either but was just confirming if there was something more I should be doing.........thanks!

Your generator should be exercised monthly. One good reason is so you don't gum up the carb, the other is to keep the genset in good working order - brushes don't build up moisture/rust etc. I think about an hour under load is the general rule of thumb. I'd take a generator with a lot of hours over one that has sat any day - they need to be run.

If you're interested in running a cleaner thru the Onan, there is a fuel pump inside the casing, and with some minor surgery, you could run off a small fuel tank or can that holds your Seafoam, STP, or whatever else you want to try running thru the Onan. Just make sure it's safe for the Onan...

Crawl underneath, and you should see a rubber fuel line exiting the generator compartment, attaching somewhere near the frame to a metal fuel line out of the main tank. Disconnect the feed hose from the main fuel tank line, and connect that up to a hose connected to the aux fuel source.

I've considered putting in a permanent bypass valve similar to the one on our fresh water tank for feeding anti-freeze into the plumbing system. That way I can exercise the generator without worrying about the level of the gas tank on the motorhome. Might also be a benefit for boondocking.

Chum lee wrote:
IMO the best additive is new clean fuel, regularly, run through the fuel lines and carburetor. That means running the generator about every month for long enough to burn out the old fuel, then, get it warmed up and put it under +-3/4 load for a few minutes. (20 to 30 minutes total run time) You can add Sta-bil, Seafoam or something similar to your fuel tank, if you want, but, IMO, running the genny, . . . . regularly, is what keeps it going reliably, with minimal fuel issues. You can drain the fuel and run the genny until dry if you know you aren't going to use it for a while. (like 6 months) Leaving the same gasoline, especially E10 or higher in the carburetor for over a month is the beginning of problems down the road.

Chum lee

Agree. Run it dry before storage if you're worried about it but in 8 years only had the one problem related to not exercising it regularly. Corroded wires leading to/from the power source transfer solenoid.
Btw, I believe stuff like Seafoam is just some form of diesel fuel. Probably not a great idea to put it in a gasoline system but it's up to the user.

I use Seafoam in the RV gas tank at the end of the camping season. I drive and run the genny on this mix for a bout 30 minutes, then park it for the winter.

IMO the best additive is new clean fuel, regularly, run through the fuel lines and carburetor. That means running the generator about every month for long enough to burn out the old fuel, then, get it warmed up and put it under +-3/4 load for a few minutes. (20 to 30 minutes total run time) You can add Sta-bil, Seafoam or something similar to your fuel tank, if you want, but, IMO, running the genny, . . . . regularly, is what keeps it going reliably, with minimal fuel issues. You can drain the fuel and run the genny until dry if you know you aren't going to use it for a while. (like 6 months) Leaving the same gasoline, especially E10 or higher in the carburetor for over a month is the beginning of problems down the road.

Chum lee

Nothing. Ever. 2002 Roadtrek with an Onan Microlite 2800, ran fine except for a solenoid replacement 8 years ago. Had nothing to do with bad fuel. Chassis engine always started and generator always started.