Onan 2500 generator won't start

Also if your batteries are low it will start to run but will die and not run.had it happen to me on a long trip due to the three way reefer running on batteries and truck alternator not keeping the charge up.

Well I tried most of those things with no success. So I took it into Cummins Northwest in Medford, Oregon. Had a very good experience. They fixed it for about 140 bucks. They said the propane pressure, the governor, and the little orange wheel (maybe the butterfly valve Skipbee suggested) all needed to be adjusted. They said those things get out of adjustment when the generator is not run under load for 2 hours a month. I sure hadn't been running it that long. He admitted that this is a catch 22 because if you can't start it you can't run it, and that many customers have this problem!

Yeah the Honda advice can not be ignored!...LOL!

Try using engine starting fluid. My generator regulator/priming solenoid is bad, so it is hard to start, but runs once it is started. I use engine starting fluid to get it going quite often. I took it to Onan and this was the diagnosis. To take it out and fix it is a P.I.T.A. and expensive. I just take the air filter cover off and spray the air filter, closer to the carb. Starts every time.

I would try everything Kheller says. This was all good advise. I did all this and still had problems, so I took it to the dealer. I promised myself that if I ever took this genny out, a Honda was going in it's place.

Several times I've had starting problems with our Onan 2500. At the generator, fiddling with the butterfly valve on the carburetor,while turning the engine over, got it started. Be sure to fit a screen filter on the hose feeding air to the carb from below, to prevent bug debris. It is important to run the generator, monthly, under load.

Here are a few things to look for: First and foremost, does it have a spark? Yes..the plug is a bit of a pain to remove. If it does not then, did you check the oil level? On some models there is a low oil shut off. Ok if these check out, you should turn your attention to the regulators. This is also not so fun but turn off the LP gas and disconnect the line going to the genny. Turn it back on. See if there is any gas flow at all going to it. If there is not or barely, one of two things; the main regulator has gone bad or the line is pinched or clogged with something. You might want to clear all of the lines. Be careful here. You will want to unhook the main regulator, stove and fridge. You don't want to clog anything else. Blow out the lines back wards. In other words don't clear the lines from the regulator hose with anything hooked up. I once had a build up really smelly liquid stuff come out of mine. Didn't know that could happen! Also the genny is lower than the fridge and stove so any stuff that might be in the line will settle at a low point. If anything is in there it will make a mess so cover the lines with some rags. A main regulator can put out enough pressure to run the stove and fridge but not enough to run the genny. How old is it, over 4 years? Is it an auto switching type? If either, 40 to 50 bucks...replace it and clear the lines now. Try and start it now. If it won't go, check the carb. Take it off and clean it out. Try again. On another note...these gennys are real finicky about air filters also. They have to be clean and new. Blowing them out does not usually help. Start with a new one. The plastic cover of the filter HAS to be seated correctly for it to run smoothly. It will sputter and run rough if either of these are not correct. Last but not least it could be the genny regulator itself. A pain to take them out...You might want to kick us down what model you have...the sticker is on the front lower part. It is a process of elimination...pain in the rear I Know...been there. Hope this helps any....Kev.

There is a warm and cold temperature setting. I'd check that out. I'd also take the air cleaner off and check for dirt/clean it. Having less air flow would also make it harder to start at higher elevation.

As far as I know, 5/8" is the 'other' standard plug size. Last time I changed mine was last year, so I really don't recall which it is.

Jim, "Mo' coffee!"

Thanks Jim,

what size spark plug wrench does that take? I have a 13/16 and it's too big.

Assuming it's a 'Micro'-type, have you tried starting it with the truck engine running (assuming you've got a charge connection to the camper)? Sometimes there's enough battery voltage to turn it over, but the higher volts from the alternator is needed to spin it fast enough to start.

You mean the bugs in the regulator vent line, right?

The plug is accessed by removing the round pop-out plug located in the black bottom part of the case. It's below the access door, to the right, in line with the plug. That works _if_ your camper's structure doesn't interfere. Be sure to reinstall the access plug; the case needs to be intact to maintain cooling air flow.

Jim, "Bills travel thru the mail at twice the speed of checks."