Hi All,

The Onan 4.0 RV GenSet in my '82 Airstream MH was running fine until about 5-6 months ago. We have had some big storms come through the mountains in Northern California this winter and the power has gone out for 8hrs at a stretch a time or two. The generator stopped working during the 100 degree weather we had last year. I use the generator to power the coach A/C when I have to move the MH from a spot to storage and back a couple times a year.

The generator had been running just great, but suddenly quit. I had suspected that it wasn't getting any gas. So, I did a little troubleshooting. Here is what I did...

Was it getting any spark? Pulled off a plug wire and inserted a screwdriver into the plug wire, held the screwdriver close to the spark plug and hit the start button. There was spark.

Was the fuel pump getting electric current during start? The fuel pump is electric and it gets 12 volts from main engine battery when the generator start button is engaged. I hooked a volt meter to wire going to fuel pump and to chassis ground on generator. Yes, there was voltage during cranking of generator starter.

Did I have gas in the main fuel tank? Yes, there was 3/4 of a tank and MH engine ran fine.

Was I getting fuel from the main fuel tank to the generator? I disconnected the fuel line to the generator. There was fuel in the line when I tipped the line down some. And, NO, I wasn't going to use my mouth to try to siphon some!

Let's try another fuel source. I connected another fuel hose to the generator fuel filter and placed it into an external fuel can. Be careful doing this. Fuel and vapors are dangerous! I cranked over the generator, but no fuel was being sucked through the fuel filter.

I then put about a teaspoon of gas down the carburetor through the air intake. Again, be very careful doing this. This can be dangerous. Do not spill fuel and do not put too much fuel into the carburetor air intake. I pushed the start button and the generator ran for a second or two and sputtered to a stop. OK, this means that the generator simply isn't getting fuel.

I assumed at this point the generator fuel pump was bad. I actually took it off and took it apart, cleaned it and put it back together but still it wouldn't work.

Ok, time to buy a new fuel pump. I went directly to Cummins to get the pump. There is a Cummins-West shop in Redding Calif and one in San Leandro Calif. I called and they had a pump. I ordered and paid over the phone and had it shipped. It was at my door step the next morning before I even got the chance to walk out side.

The cost of the pump was $171 plus tax and shipping.

It was about a week and a half before I got back up to the property to install the pump. Installation is easy and quick. The pump is shipped with some sort of liquid inside of it. I tried to empty out as much as possible. I cranked the generator starter for about 5-10 seconds and it came to life. It smoked until it was cleaned out and warm.

The generator is now running great.

One of the links at the following site will allow you to sign up for an account and then you can download pdf files of any generator operators manual and parts manual. It is irritating that companies require you to "sign up" to get this info, but it is worth it here if you don't already have these manuals.

http://www.cumminsonan.com/rv/

The old generator is kind of noisy and smells of exhaust fumes when running, but it works great and I can't really see spending lots of money (thousands) to buy a new quite one for the few times a year that one is really needed.

Dean