Onan 5500 Gas Generator

Pull the bowl by loosening the nut on the bottom of it, drain the water, spray it and the intake with a can of carb cleaner from the parts store and after letting the pump refill the bowl, start it. May be all it needs and will save 175 dead presidents.Not sure but if it does'nt have aside plate or top cover then remove the bottom and look around.

Read the instuctions on the seafoam can!, If you disconnected the fuel line and ran it out of a gas can treat the gas can. Get the seafoam into fuel and into carb , shut it down and let it soak. This process may take a day or so to shoot itself in the foot. Keep you gas treated with seafoam when rv sits for periods of time. The aggrivation from a gummed up genny is worth the ten bucks to treat your fuel. Like others have said exercise the genny. Mine sits alot to I have had my share of problems from this also.

You could add Seafoam to the tank which would be four or five cans to treat 80 gallons if memory serves me correctly. Another approach would be to disconnect the fuel line at the generator and mix Seafoam in a one gallon gas can. Place gas can higher than genny for gravity feed and run for about 30 minutes. Wait 30 minutes, then run generator for another 30 minutes. If the generator runs fine, re-connect to the fuel tank line.

My fuel tank is full. If I add seafoam to the gas tank on the motor home, will this help to get the fuel to the generator? with an 80 gallon tank, how much seafoam do I add? To get to the carb, do I remove the plate on the bottom of the generator?

Great posts by Paul and others.

Most likely your genie is just suffering for the "I ain't run it too long and my fuel has gone sour" blues.
Some might take it to the local cummins shop for some big busks repairs, but really, what Paul outlined above will fix it right up.

I'd add that you should put a double shot of stabil or seafoam in the RV tank, or of she is being horribly stubborn, in a gas can with the gennies fuel hose stuck in it.

This is a lawnmower engine. Nothing fancy, and nothing complicated. The 20hp v2 Yamaha in my toro is way more complicated than the onan 5500 in the gasser I used to have.

Carb cleaner and starting fluid will be your friend.

In the future, stabil or seafoam, fill the motorhome tank to the top, run the genny half an hour (under load, turn on both a/c's) before any storage that will last more than a month. If you're not sure then just do it, certainly cannot hurt.

Probably the carb but could be other stuff like
Corrosion in stator etc or even the regulator.
If so it needs to come out and apart.
Is there a Cummins dealer nearby?

Seafoam is great stuff. I add several cans after the last trip of the fall even though I run the RV and the gennie every two weeks all year. I actually think my generator runs better now than when I bought it.

As to the Onan carb. I haven't rebuilt mine but, they tell me that it can be done. Just be careful not to break anything as replacement carb parts aren't available.

Run seafoam through the carb first. If that doesn't cure the problem, then check fuel filter and lines. Ethanol in gas literally gums up the works!

all good suggestions.

If you suspect fuel or a fuel line issue, this what I did. I had a fuel line issue or suspected one. Genny wouldn't start or I should say, started and then crapped out. So, I did the following.

- Remove fuel line from genny.
- Got a 3 - 4 foot piece of fuel line and a gas can full of gas.
- Hooked everything up to the genny.
- Genny started.
- Followed fuel line all the way back to tank and cut line as close to tank as possible.
- Bought enough fuel line to replace old line and spliced in new line.

Once I got the genny started I removed the filters exposing the carb. I then sprayed carb cleaner into the carb to give it a good cleaning. Lots of yellow junk came out. Waited for the cleaner to evap and then started the genny again. With the genny running, I sprayed the carb again with short bursts of cleaner making sure the genny never stopped, did this several times. The genny now purs like a kitten.

What I found was that the old fuel line had dried out and was most likely allowing air in. Using the gas can and small piece of fuel line helped me to eliminate the gas in the tank and the existing fuel line.

-paul

jolooote wrote:
Thats the reason the book & EVERYONE says to excercise it 2 hours EVERY month. You may now have varnish in the fuel system & top end. Very expensive to have Onan rep. clean it.

That was my first thought; you need to have the carb cleaned.