Generator problems

Kingsmen55 · 08-08-2020, 04:25 PM

My Onan Generator on my 2004 Sightseer Class A won't stay running.
Fuel pump and filter replaced two years ago. I only ran it for 24 hours since then. I start it often. any ideas? Thank you

Goodspike · 08-08-2020, 04:39 PM

If it's a steel gas tank there could be lots of rust going through and clogging the filter.

Morich · 08-08-2020, 04:58 PM

Engines of any of this sort take three things to run, Fire fuel and air but in the right amount of each. We don't have much to go on from the description , so I might suggest looking at the engine a bit closer to see which is being lost if you are telling us it starts but then stops. How does it run while running? Does it run well and carry the load when running? How long does it run? Long enough to let it overheat or just long enough to say it ran? After it fails, does it restart immediately if cranked?
Most generators are not known for this, so we will need far more info to begin any real look at what's going wrong.

akeagle · 08-08-2020, 11:46 PM

If yous generator runs on gasoline, is your main gas tank fuel level less than 1/4 full? As I understand, some or all gas generators tap the main fuel tank at the 1/4 tank level so the genney can't run the tank dry and leave you stranded in the boonies somewhere.

Wyatt · 08-08-2020, 11:55 PM

Quote:

Originally Posted by akeagle

If yous generator runs on gasoline, is your main gas tank fuel level less than 1/4 full? As I understand, some or all gas generators tap the main fuel tank at the 1/4 tank level so the genney can't run the tank dry and leave you stranded in the boonies somewhere.

I’ll second that as a first issue to eliminate...way too many variables beyond that, given the info...

345 desoto · 08-09-2020, 07:25 AM

Check the generator oil level...

Kingsmen55 · 08-09-2020, 09:23 AM

My Onan 4000 is performing as follows: Starts up fine first time, runs with A/C for about 15 min. then starts to shut down. But takes 3-4 times of surging before it finally shuts down. I started it again same thing happened but only ran 5 min. before surging. Tried again but would not start. Checked oil it was ok. Two years ago I had the fuel pump, starter, fuel filter and plug replaced. It's only had 24 hours on it since then. I go out and start it about every few weeks. I took it in Friday they replaced the coil it ran but stopped running on my way home. I feel like it may be running hot and turning it self off but not sure. I was looking for input from this forum. I am a new member. Thank you for your time and any input you can offer.

Morich · 08-09-2020, 09:34 AM

ARGH!! One of those types!
I'm not a good mech and gensets are one which I don't have much trouble with over the years but off the top, it does sound like overheating or a fuel problem where fuel gets to the engine enough to run but then it is not getting enough to keep running. Maybe something in the fuel lines or filtering???
But a check of how it gets air to cool might be good to look over as rodents and such can build a nest here and there. We would think they would have seen it when changing the coil but then that is hoping somebody else did there best job and I like to look at it myself.
Pretty short on ideas from there, though. Good luck to you. Be safe.

Goodspike · 08-09-2020, 09:37 AM

Assuming your fuel level is well above a quarter tank, I would again suggest the fuel filter.

How hard is it to change that out?

Years ago we had a boat with a ceramic filter in a glass bowl, so it was easy to see. Given the marine use, steel tank and pounding from waves creating motion in the tank there was a lot of rust coming through the system. It needed to be cleaned out every few weeks.

The other thought is that maybe water made it through the filter. How difficult is it to drain the carburetor bowl?

BTW, not even sure why changing the coil was seen as a solution. Sounds like someone just throwing parts at a problem.

kb2ztx · 08-09-2020, 06:39 PM

Quote:

Originally Posted by Kingsmen55

My Onan 4000 is performing as follows: Starts up fine first time, runs with A/C for about 15 min. then starts to shut down. But takes 3-4 times of surging before it finally shuts down. I started it again same thing happened but only ran 5 min. before surging. Tried again but would not start. Checked oil it was ok. Two years ago I had the fuel pump, starter, fuel filter and plug replaced. It's only had 24 hours on it since then. I go out and start it about every few weeks. I took it in Friday they replaced the coil it ran but stopped running on my way home. I feel like it may be running hot and turning it self off but not sure. I was looking for input from this forum. I am a new member. Thank you for your time and any input you can offer.

Same issue on my fathers Class C last year. Oil was overfilled. We drained some oil until it read properly and ran fine for 16 hours after that. I did alot of searching on this issue and when someone said to check the oil i thought they were nuts. Well its been over a year and he runs it all the time now with no issues.

Kingsmen55 · 08-10-2020, 10:20 AM

Thanks we did check the oil. I appreciate your response.

**creativepart** · 08-10-2020, 10:53 AM

I used to own a Forest River Class C that did this exact same thing. It drove me mad. It only happened on really hot days. It would run in the morning fine but by afternoon it would stop running every 20 to 30 mins after a restart.

So, I took the RV to a Cummins Service Center - they ran it in the parking lot for 8 hours on a hot day. It never stopped once. They actually used a 1/4 of a tank of gas doing it. Charged me $250 and never touched a thing.

On my next trip it did the same thing.

I wish I could tell you how I fixed it - but I never found a fix. Ever. I traded that (lousy) FR for my Winnebago and never looked back.

When it stalls it will flash lights that give an error code. Like it will flash once, then wait and then flash 4 times. You can look up the error code on the Onan website.

But that never helped me.

Morich · 08-10-2020, 12:08 PM

I hate to say it but I have the odd feeling that we may be reaching some sort of crisis on repair of things as there seems to be more and more stuff to throw away instead of fix.
I have a Focus which is beginning to look in that spot as it throws a code and tells them what to change but changing that does not fix the problem and they seem to have no way to trace the signal from one electronic box to the next. And there are way too many boxes which all have to agree to let the car crank! I had hoped truly hot weather would make it totally fail but that's not happening.
So it sounds like you may have covered the most common items, so thinking what else might be going on, I get around to really sad items but "might" make sense. As it sounds like heat related, it could be some connection in the electronics but there is also a idea in my mind that it might involve something more drastic like lack of oiling to some part like the piston rings so that they are running hot enough to fail. A compression test might help to sort out a problem there?
But the big downer for that is anything of that major group gets into bad news like changing out the engine!
Other, more friendly thoughts might say a crimp in a fuel line to restrict flow to the point of failing when running but let it get enough fuel to start the next time?
Getting way weird in that lineup!!
I'm not enough mechanic to know if there is a way to test fuel flow through lines??? Get "X" amount of fuel to meet specs?

HotMech · 08-16-2020, 05:56 PM

Kingsmen55, it would seem to suggest that there is a leak between the pump and the tank. Check to see if you can rotate the fuel hose, on the fitting at the pump, its under the bottom of the gen. If it moves there is an air leak. It will show up when the line heats up. The air is easier to move than the fuel. After it cools, it kind of seals up a bit, and the whole process starts over. Check the hose on the pump inlet, and at the top of the tank. If its easier, just replace the entire hose from the pump to the tank fitting. Happy diagnosing. Kerry

tedskeet · 08-16-2020, 07:12 PM

Take the hose off the carburetor and put it in a container push the prime botton and see if you are getting a good fuel flow that will tell you if the fuel pump and filter are working.

tedskeet · 08-16-2020, 07:41 PM

Also once you get it running let it warm up for a couple of minutes then put a load on it like your a.c.those gen.are very funny if you don't put a load on them after a while they will shut down.good luck.

charliedias · 08-16-2020, 09:03 PM

My War Story.

Winnebago Spirit 26A 2017.

1st Season 2018 Hunky Dory.

2nd Season 2019 Took RV in for a complete
pre-season preparation.
Had them change the oil/filter on the Onan anyway.

First use in 2019 season - Onan won’t stay running.
Went through all the tricks & MUCH research.
Discovery ? Faulty Dipstick Full Markings ! 😳

Drained about 1 pint to slightly LESS than 1/2 filled.

Runs perfect. Each & every time. Stays running.

Wazzup with that ? I was almost ready to replace a pricy Onan Generator over faulty dipstick markings !!

ldfeat · 08-17-2020, 01:47 AM

All onans will display a fault code via a series of flashing lights in the start switch. Look in your owners manual for the fault codes and remember to look at the start switch light the next time it shuts down. You can also recall any fault codes with a series/sequence of pressing the start button which is explained in the book. Or, maybe you can Google it if you don't have the book. Good luck, Larry, 2014 Reyo P

Bo Walker · 08-17-2020, 03:03 AM

Kingsmen55, I had a similar problem which was a bad voltage regulator.
Good Luck and let us know the solution.

fkempf216 · 08-17-2020, 07:10 AM

I agree with kb2ztx that an overfull oil pan will cause a problem like yours. I read a few months ago that a gentleman explained his problem was the same as yours and he spent hundreds trying to get the problem fixed before he removed some of the oil from his genset and bingo his problem was solved. The gentleman explained if you fill the oil to the full mark on your genset it will be overfull when the oil gets hot. I have since removed about a pint of oil from my genset and it's been running fine.