Onan generator turns but won't start

[baloo]

I noticed a few postings about Onans turning over but not catching once the starter button is released.

I have an 03 Sun Voyager, and I have that problem. Is it possible that there is a starter switch inside the coach that must be turned on to start? We're new to the Sun Voy, and there are some switches up front that are puzzling. Also, I'm totally in the dark concerning the converter fuses/switches and other fuse locations.

I added 20gals of gas to the tank, thinking the generator pickup was not being fed, but that didn't help. The gas tank is 75gals, so I can't believe that it wouldn't start with 20gals.

I'm worried that it's in the oil pressure circuit.
Does anyone know how to bypass this oil-pressure shut-off circuit?

Any other ideas?
Thanks.

[Stevegd007]

Most generators need a least 1/4 tank of fuel in the RV fuel tank to run. Even with your fuel gauge showing a tad over 1/4 sometimes the generator will not run. Adding 20 gals of fuel to an empty fuel tank may not be enough. Then you should not have 2nd button to push to run the generator. Just one. Onans will also have a starter switch "ON" the generator, behind the cover. Check to see all fuses are OK on the generator. Next if you have not changed out the fuel filter...an 03 RV...might have a look see at replacement of the fuel filter for the generator.
Best of Luck.

[Sundancer268]

Re the switch inside. If it is an Onan there is no switch inside that has to be operated Either switch will work with out the other switch being touched. If the engine is firing when you hold the start button on and quits when you stop pushing the button, you might have a failed voltage regulator or low oil pressure. Have you checked the oil level to verify it is where it belongs? I would also check the Onan WEB site and see if you can find any information on your generator. Good Luck.

[baloo]

MH still in the garage getting "serviced." (Now starting the 3rd week!) Am sitting here fretting and anxious to try out the recommendations.

[GULFer]

Is the motorhome new to you? If it is, I had the same problem until service manager explained how to prime generator from the dashboard switch. I don't remember if there is a primer on the outside panel. You prime it by pushing top portion of switch for 10 or 15 seconds and then push lower portion of rocker switch to start.. Good luck

[baloo]

Quote:

Originally Posted by GULFer You prime it by pushing top portion of switch for 10 or 15 seconds and then push lower portion of rocker switch to start.. Good luck

Yep, there was a little sign by the switch explaining the prime. I'm pretty sure it got to point, after numerous tries, that I was smelling gas.

I'm still stuck at the mercy of the whim of the service station, awaiting the MH's completion so that I can try all the suggestions!

[BattChief7]

I went through a similar problem. Mechanic could not get any spark but coil showed good. He thought "trigger" on crankshaft had broken and took generator apart to replace. Turned out that the "pin" connectors on wiring harness were loose and corroded. replaced "pins" in connectors and genset ran fine. Just a thought.

[George Schweikle]

This may not suit everyone, but I went through two seasons of intermittent problems with my generator before taking a friend's advice and going to the nearest Cummins Onan service center. While there are probably many independent locations that can provide excellent generator service, and this forum also has excellent tips and advice, the Cummins Onan people had the test equipment and experience to correct my problem. They had one tech that did nothing but work on generators.

The generator is a Microlite 4000 that sometimes ran fine, but other times it wouldn't run under a load. I replaced the fuel line from the gas tank, changed the fuel filter, spark plug, and air filter, and verified the fuel pump was working. The Cummins Onan tech checked everything, and talked me through the process (did you know there is a reed valve inside the valve cover that must be cleaned?). It turned out that several things were slightly out of adjustment and combined to cause the problem. In this case, my money was well spent by "going to the source" where there was an expert.

[baloo]

George/BattChief,
As reluctant as I am to bringing the coach in (time, lack of faith in mechanics, difficulty in getting everything together to drive the monster out to a shop) -- I'm thinking that maybe the best thing to do is to just pay someone to figure out the problem.
I've gotten some good advice, including sending the control board to be checked, BUT I'm finding that there are a myriad of minute defects that could trip up the elephant, so to speak -- like those pins in a connector which Batt found. Incredible that it even was localized down to that!

[DpDave]

Baloo, I have an Onan 5500 Elite in my 5er. When I bought the unit, I had know idea how long it had set up with out having run the genny. I went down to speak with the Onan/Cummins guys and got 2 suggestions.

Firstly, and easiest, was to take apart the carburetor and clean it. This was actually a simple job, involving a few hand tools and a can of carb cleaner. Fortunately my genny is very open for that job. The tech pointed out that if the carb was too crudded up for the carb cleaner to work, I could bring it in and hot tank it for a day. Anything more serious, they just replace the carb.

The second option he had mentioned, was that they had been seeing a problem with mice climbing up into the rotor space. When you hit the start button, the rotor spins, whacks the mouse, makes a mess, and breaks an arm off. With an arm off the rotor, no start.

Fortunately, the carb cleaner fixed me up. I now run mine on a load on a regular basis.

[baloo]

Well, I finally got the MH back and finally got to trying some troubleshooting things out.
Once again, this is an Onan 7KW gas Gold Marquis, carbuerated (HGJAB).

I removed the air filter, and it was soaked with gas.
I then tried turning over the generator, and gas was squirting out of the carb.
I let the generator sit about 10 minutes, moved the "altitude" dial way over, and then tried starting it without priming it. It started and ran for about 1 minute! This is the very first time it has started and run.
Heavy black smoke came out, I'm assuming due to a very rich mix.
Then, the genset cut off and would not start all over again.

If I drained the carb bowl, it would start for 2 seconds and then immediately stop. Subsequent attempts to start would fail. It's only when allowed to sit, would it seem to try to catch for a second or two.

I pulled off the fuel solenoid switch which is on the bottom of the carb, and I tested it with an ohmmeter. I got a high reading across the leads regardless if the plunger was pushed down or not. I take it that the solenoid is not doing its job of turning off the fuel pump when the float reaches a certain level??

1) Would this be correct thinking??

I'm thinking that the fuel pump keeps pumping because the cutoff solenoid is not kicking in, so it is flooding.

2) I cannot get to the carb mounting bolts because they are on the backside of the genset. The gen cover is preventing me from even getting a contorted angle at the bolts.

Anyone have ideas how to remove the carb without taking the generator totally out of the MH??

[RV Wizard]

It is flooding because the float in the carburetor is sticking not shutting off the fuel and sticking again not allowing the proper amount into the bowl. You may try removing the bowl and cleaning the float and valve assembly with the carburetor still on the engine.

[Jim2668]

Same problem, mouse had chewed the supply line.

[ga traveler]

Quote:

Originally Posted by baloo Well, I finally got the MH back and finally got to trying some troubleshooting things out. Once again, this is an Onan 7KW gas Gold Marquis, carbuerated (HGJAB). I removed the air filter, and it was soaked with gas. I then tried turning over the generator, and gas was squirting out of the carb. I let the generator sit about 10 minutes, moved the "altitude" dial way over, and then tried starting it without priming it. It started and ran for about 1 minute! This is the very first time it has started and run. Heavy black smoke came out, I'm assuming due to a very rich mix. Then, the genset cut off and would not start all over again. If I drained the carb bowl, it would start for 2 seconds and then immediately stop. Subsequent attempts to start would fail. It's only when allowed to sit, would it seem to try to catch for a second or two. I pulled off the fuel solenoid switch which is on the bottom of the carb, and I tested it with an ohmmeter. I got a high reading across the leads regardless if the plunger was pushed down or not. I take it that the solenoid is not doing its job of turning off the fuel pump when the float reaches a certain level?? 1) Would this be correct thinking?? I'm thinking that the fuel pump keeps pumping because the cutoff solenoid is not kicking in, so it is flooding. 2) I cannot get to the carb mounting bolts because they are on the backside of the genset. The gen cover is preventing me from even getting a contorted angle at the bolts. Anyone have ideas how to remove the carb without taking the generator totally out of the MH??

#1 the solenoid does not cut off the fuel pump. The fuel pump runs all the time. The fuel is shut off by a needle valve, when the fuel is at the correct level. The purpose of the solenoid is to shut off fuel flow into the carb. when you shut down the generator. It sounds like the needle valve is stuck, allowing the carb to flood.