Community Forums

udbe2 · 05-06-2009, 08:51 AM

We have a Onan Genset that we have not been having any problems with until now. In the evenings after work the generator will start up after we fiddle around with it however in the mornings the generator will crank but won't start. It gives me an error code of 14 however the genset had not been running.
Yesterday we changed the oil, replaced the oil and fuel filter and the generator started right up. It has 3/4 tank of gas and the fuel pump is working fine. We were going to replace the spark plugs however the parts place told us we had one spark plug even though I told the woman I had two so my husband only brought home one spark plug.

This is the only thing I can think that could be wrong except maybe the fuel cap is not vented but this has never given us any problems before. When I go to put gas in the filling station and remove the cap it will suck air in. It did this yesterday evening so I am thinking that after I filled up the tank w/ gas and hubby went to start the generator he thought that the oil change, fuel filter and oil filter change worked. This morning when it wouldn't start he told me to check the oil level which was full however he insist that is what the problem was but I don't think it is the problem.

Has anyone had a problem with the gas cap not being vented causing it to not start up until you take it off and put it back on? I was thinking that maybe it is the oil sensor unit however that doesn't make sense to me since it will start in the evenings after I open the cap and put it back on. I will be replacing the spark plugs this evening when I get another one so I can replace both at the same time.

Gary RVRoamer · 05-06-2009, 01:33 PM

The fuel tank should be vented, so that's a problem in any case, for both the engine and the generator. The vent may be in the cap or via separate vent hole in the filler neck. The small fuel pump in the generator probably cannot overcome much suction.

You can test your theory by loosening the gas cap before starting the genset in the morning. Crank it to see if it starts without loosening the cap. If it does not, loosen the gas cap and crank it again to see what happens.

udbe2 · 05-07-2009, 09:31 AM

We tested that theory last night and it proved to not be the case. We were able to get it started last night and this morning by playing with the butterfly and the throttle linkage when the generator started to crank. I am beginning to think that the carburetor will need to be replaced. I have heard that is a common item that goes bad with these generators. I would put a rebuild kit in it however I've been told that they don't make one for this carburetor. The altitude is set correctly and nothing has been touched on the carburetor so there must be some varnish that is in the jets or the bowl that is causing the problem.

I spoke with an Onan/Cummings mechanic and they are lost about what can be causing it to not want to start. They do agree w/ me about the code error not being correct since the generator wasn't running and shut down by itself.

mfire1339 · 05-07-2009, 10:11 AM

Sounds to me like the choke butterfly is sticking and not closing. I would spray it and linkage with carb cleaner and work the linkage till free.

Mike

John Hilley · 05-07-2009, 10:58 AM

How many hours on the generator and how old is the motor home? You may have a bad section in the gas line from the fuel tank to the generator. There usually is at least one rubber tubing connecting the steel gas lines. If it is cracked or kinked it could cause a problem. The difference in starting between morning and evening seems like it must be temperature or moisture related.

udbe2 · 05-08-2009, 07:43 AM

The generator is actually on a 06 Raptor. The generator has 108 hours on it. It will start a lot of times if you hold the butterfly closed and when the generator starts to increase RPMs allow it to open half way until it stays running. There is a bit of varnish around the butterfly however I've been told that carb cleaner isn't the best thing to spray it with but to use the Seafoam. I was going to spray it this morning to clean it and allow it to dry during the day until getting home. I'm also going to replace both spark plugs this evening to see if that may help out. I've only owned it for 6 months now however it did sit at the dealer lot for about a year before I bought it so it may have had some gas in the lines that was not cleared out completely before sitting.

John Hilley · 05-08-2009, 09:19 AM

With the low hours it does sound like a varnish problem. The best solution is to mix Sea Foam in a gas container and disconnect the fuel line to the generator from the motor home gas tank and stick it in the gas container with the Sea Foam mix. You probably will have to make an extension with a length of tubing compatible with gasoline. The fact that it slowly builds up speed pretty much confirms the diagnosis.

ROMAD · 05-08-2009, 04:40 PM

Just had to replace the carb on my gen set and it had 100.4 hours on it. My fault though, I didn't crank it during the 3 months I was parked in Pensacola, FL. Expensive lesson but one I will not repeat. I used Advanced Services and Parts LLC and picked up a carb for $177.00 and put it on myself, it was easy. You are correct, no rebuild parts kits are made for these units.

udbe2 · 05-11-2009, 06:51 AM

I thought that I had it fixed. I used the seafoam however that didn't work so I checked on a new carb. $148.00 however they won't have it in until tomorrow. We bought some thyme and soaked the carb after removing all of the gaskets and plastic on it. After about 1 1/2 soaking we put it back together, the genny started right up with no problems or hesitation for two days morning and night. This morning it decided to give me one heck of a time starting and I had to mess with the butterfly again to get it going. Holding it down until finally it would stay running. I want to say that maybe it was my fault last night for letting it get down below a quarter of a tank of fuel before adding some this morning but I don't know if that caused it to have problems or not. The repair shop was telling me that it takes them normally 1 1/2 hours to replace the carb LOL that was funny since it didn't take that long for me even with the top cover on. I'll have to wait until tonight after work to see if it will start right away or if I will just have to replace the entire carb. Maybe there is some trash in the tank and when it does get low it sucks it into the carb? It didn't have any problems when I kept the tank at 3/4 to 1/2 full. Just when I let the level get down below 1/4 tank. hummmm any thoughts?

peter griffin · 05-19-2009, 06:55 PM

Sounds like to me you did not run it enough. It can gum up quick and the fuel filters somethimes can dry out and go bad.

Run it once a month for 15 or 20 minutes under a load. Makes a big difference. Good luck