Need help with Onan generator, starts and dies

[rjdelapp]

First off I want to thank everyone for their post on here. I have read thru hundreds of threads looking for and finding help with problems I have with new to me, Damon Daybreak, 98 with Ford F53 460 chassis. Now to my problem with the generator which is a Onan 5000 98 model, no display for codes and has only 2.6 actual hours on it. It will start right up but dies as soon as I release the start button. It still has fuel but no fire to plugs. I can hold the start button in and it will run as long as I hold it in but bad for starter motor. It is not a carb issue because I had to rebuild it and it runs smooth while running. Somthing in electrical or circuit board shutting it off.
The coach set without being used from 1998 to last week and only driving was to have it serviced on yearly schedule. It only has 2,272 miles on it but nothing worked except the slide. The levelers were rusted up and the hydraulic motor was locked up from water in it. The house batteries were replaced in 09 and they put the positive lead that feeds the power panel under the hood on the ground post. When emergency power button was depressed it created a direct short with engine battery and melted the solenoid but no fire! This is only the beginning of problems as I haven't put water in it yet and the brakes lock up. At least I can fix the brakes from reading the post on here. Thank you

Jim

[Iron Man]

Maybe low oil pressure, I would change the oil and and all the filters oil,gas and air especially if they have not been changed since 98. May have some electrical issue from the battery being hooked up wrong. Got to start somewhere. Check the easiest and cheapest things first.

[TW]

Not ENOUGH Hours on the GEN clock....

You know, that you need at least 1/4 Tank full of Fuel?

I go with my GEN once a year to Cummins (ONAN) to have it serviced....

Since you have soo few hours on the GEN, I would bring it to an ONAN Dealer for a good check-up.
Once it runs, have it work at least once a month for an HOUR under load (Spaceheater in Winter).

[rjdelapp]

I have changed the oil and filter. The air filter looks new and fuel filter flows freely. On the battery issue the voltage was correct to the generator just mixed between house and chassis battery at solenoid. Thanks for your help.

Jim

[gauto5150]

If it's the setup I think it is, the same switch that will start it will also kill it. Maybe the switch is bad, do you have one inside the coach and one on the genset itself?

[Chuck 1935]

My son had the same problem. If it starts and runs while you hold the starter button and dies the moment you release it, I believe you have a bad exciter coil winding in the generator. Below is the name and information from a company that has control boards that eliminate the need for the exciter winding.
You can confirm this by going outside and ussing the onboard generator starter button and when it starts, give it a little gas by holding open the carburater a bit and see if it revs up. If it revs up and then dies when you release the starter, you need a replacement board that will eliminate the need for the exciter winding. Give them a call and explain what you need. They are very helpful.

Generator & RV Controls | Engine Monitors | Idle Limiter | Repair & Rebuilding Services

[rjdelapp]

It does have switch at drivers seat and at generator. I disconnected one to drivers seat and still shuts down. The switch at the generator looks good and clicks each direction but it is connected to circuit board. ??
Thanks
Jim

[rjdelapp]

I believe Chuck is very close based on my limited past experience. Its like the generator should produce its own ignition power which is cut off when I release the start button. It also could be part of the safety circuit which keeps it from running if not producing current.
Thanks, I will call Flight Systems first thing Tuesday.

Jim

[rjdelapp]

looking at Flight Systems web site I came across a very good troubleshooting guide for Onan generators with step by step instructions to determine if you have control board or regulator, etc. Even tells which pin to check if oil pressure switch is working. Here is the link. RV Generator Controls Cross Reference Guide | Generator Controls after opening the web page you have to click on the blue letter two line link to pdf file.
I saved file to desktop to use tomorrow. Chuck you are the man!

Jim

[jamesgr81]

Just remember as a general rule the controls are bypassed when starting. So if generator runs while starter button is held down then the engine is fine - the problem is in the controls. So gasoline supply, carburetor or ignition is not the problem.

The generator will shut down if low or no oil pressure or the the alternator is not producing voltage.

The exciter provides dc power to the generator rotor to produce the magnetic field necessary to provide AC output. If this circuit fails generator will not run.

[ga traveler]

Originally Posted by jamesgr81

Just remember as a general rule the controls are bypassed when starting. So if generator runs while starter button is held down then the engine is fine - the problem is in the controls. So gasoline supply, carburetor or ignition is not the problem.

The generator will shut down if low or no oil pressure or the the alternator is not producing voltage.

The exciter provides dc power to the generator rotor to produce the magnetic field necessary to provide AC output. If this circuit fails generator will not run.

James is right on the money. The only thing I would add is,Low oil or too much oil will cause this as will a bad board.

[olydigs]

My Onan 5000w also would turn over, fire then die, gas level was ok, I then turned the adjuster on the bottom of the carburetor (it is for high country operation), a full turn, and then back, and it started on the next try. My guess is that ther is a needle valve that was gunked up, and did not allow full fuel flow.

[rjdelapp]

Found the problem - the control board does not field flash the generator at start up. I ordered replacement board from Flight Systems for 129 bucks with free shipping plus 2 year warranty. These people are all about generators and their troubleshooting guide is terrific. Thanks to all for the help.

Jim

[trackman]

The ground connections on onan are notorious for coming loose.It has to do with the type ends they use.Check front and back cables.When the starter is engaged it passes the ground enabling the motor to run