Community Forums

arboldt · 03-30-2017, 04:28 PM

I had a similar frustration with my Generac generator. Also, I'm assuming Onan is a diesel generator and mine is gas. So, with a different brand and fuel, this may not apply or be similar.
I took mine to a generator shop when we were passing through Northern California (can't even remember the city). Basically, the choke control wire rod had gotten dirty over the years. He took off the cover to the choke solenoid, cleaned the wire rod, lubricated it, and told me what he'd done so if I ever had the problem again I could fix it myself easily.
Like I said, it's a long shot for you but worth checking.

Navy80to04 · 03-30-2017, 06:39 PM

Had the same troubles, replaced fuel pump ( 5th wheel toy huler ) still. So we just got a new c class camper. Trouble gone.

dave&ginny · 03-31-2017, 09:17 AM

I had this same problem with a 5th wheel I had that also had a 5500 onan. it turned out to be a governor adjustment.

I took the front cover off the unit and started it while holding the governor spring. once I decided it was governor related I took it to a shop and they adjusted it correctly. The technician said the unit was sensing a "over rev" situation and therefore it was shutting itself down. The adjustment was very small, but enough.

good luck

winniman · 03-31-2017, 10:10 AM

I had a similar problem with my onan 5500. It would start for a minute then shut off. Turned out to be the ground was bad. Try taking a jumper cable from the frame ground to the genny ground. Mine didnt have a ground connection except for the strap at the rear of the motor which only grounded to the carrier. My friend says everyone checks for power to the genny, no one checks the ground. We put on the jumper and it ran. We then bought a piece of I think 2 gauge wire and permanently ran the new ground from the one on the side wall to the genny ground on the side of the genny. Never had a problem since. Maybe you will get lucky and yours is the same.

Old Rocker · 04-02-2017, 10:25 PM

I may be sticking my nose in where it is not wanted, but i had a similar problem with my Kohler gas generator. It would try to start as long as the switch was in the start position, but die when it was released. The rv tech that i used told me it was the control board, but when i called the supplier of the board and told him what diagnostic light were lit, he told me the board was ok and that i needed to check the "flashing" current. I turns out it has what we in the car business call a crankshaft sensor. It read the teeth of the flywheel going past it and tell the board that it is ok to leave the pump on and the carb shut off valve open. There should be a resistance value in the manual so you can check it.

I had to pull the genny to replace the sensor, but the good news was it was only eight bucks at a local mower shop!

Good luck to you

ZonComGMZ · 04-07-2017, 07:24 PM

Took it in. It ended up being a problem with the Magnetos. They were both replaced and everything is working again. Thanks everyone for the suggestions.

ZonComGMZ · 05-08-2017, 07:34 PM

Now the Generator is overheating. It seems now that it is about 80 degrees out when it runs it only runs for about 20 minutes than shuts down. After about 10 minutes of cool down it only runs for about 5 minutes. I have the original cover on and there is no blockage I can see of. Any ideas? How does the airflow run inside this compartment?

pchuckie · 05-08-2017, 07:51 PM

How do you know it's overheating?
What fault code does it give? Press stop 3 times, once it flashes a code press stop once more for the 2 digit code

From memory I don't recall a fault for excessive heat on your model genset.

Do you have downward airflow out the right side when looking at the control panel? The exhaust and cooling air comes out the right side as I recall.

ZonComGMZ · 05-09-2017, 08:31 AM

It runs fine up to about 80 degrees. Anything over that and it shuts down till it cools down. Code 36 which just indicates premature shutdown. Vents out to bottom right. Thinking it may be the fuel filter getting too hot.

OLD1SGT · 05-09-2017, 08:47 AM

I didn't read all the post for this, but I can tell you I had the same issue and it was the pump.

pchuckie · 05-09-2017, 11:44 AM

Could be as simple as a loose fuel hose clamp

ZonComGMZ · 06-04-2017, 08:38 PM

So I gave up and brought it in to a RV dealer. They thought it was the pump also so they replaced it. Seemed to run fine for a month now. Yesterday the same thing started happening again. We are in Texas now and driving during the day with the generator on so I am sure it is working hard. Now it runs for a bit and then shuts off. I have to let it cool down for a bit and then it fires up again and runs for about 15 minutes. Ughhhhh. So aggravating. I need a reliable generator to run so we can have the AC units running while living in the RV not only for us but also our 2 dogs. I'm at wits ends. Nobody can figure it out and fix it once and for all. I have been to 4 mechanics and still not fixed. Maybe it the nature of the beast for these fuel pumps to fail when they get to a certain temperature? I don't know. The only thing I can think of now is to make sure I get more airflow over the fuel pump which is mounted underneath the generator bay. I was thinking about getting something like this to increase the airflow.
https://www.amazon.com/Marine-Electr...A1Y0HH7RBEPJMM

Any other ideas??????

cruzbill · 06-04-2017, 08:42 PM

How about adding an electric fuel pump upstream of the gen fuel pump. Just an idea.

UFO Pilot · 06-04-2017, 08:57 PM

Do you still have 2 fuel filters or has the "update" been done. The top filter is replaced with a special hollow fitting that is the length of the filter that is removed. I would remove the filter(s) and run a straight hose from the fuel pump to the carb and see if it will run. I have the part number for the top filter replacement if you need it.