Generator stops after an hour or so.

[prepilot_3ck]

Yalls,

So, I have this 2016 class-A. It has about 6,000 miles on it, and a 5500W gas generator. The generator has about 300 hours (I think) on it.

It seems to start ok for the most part, sometimes it struggles, but it fires up. It will run for a period if time... and hour... hour 1/2... maybe 1/2 hour then it sputters out and quits. I can restart it, but it dies right away. The little light on my starter switch flashes after this happens. If I let it sit, off, for a LONG time . Like HOURS or over night, the flashing on the switch will stop and it will fire up again... then die again after a period of time.

Load doesn't seem to matter, parked vs. driving doesn't seem to matter. It just runs for some time, then pukes, and may or may not restart. I don't have my auto start turned on or anything.

It "feels" like it might be over heating. It's hot here in Vegas, and I can only imaging what the air trapped between the road.ground and the underside of the RV would be. Anyway, I'm not really sure how to trouble shoot this. There are no temp gauges or lights on the generator to indicate why it shut off. I called my RV dealer and they said "add stable to the gas tank and some sea foam". They think it's bad/stale gas or a gummed up carburetor.

Anyway, I don't think it's the gas, but I suppose it could be. Anyone else have any suggestions?

Thanks,
Brian

[tropical36]

prepilot_3ck wrote:
Yalls,

So, I have this 2016 class-A. It has about 6,000 miles on it, and a 5500W gas generator. The generator has about 300 hours (I think) on it.

It seems to start ok for the most part, sometimes it struggles, but it fires up. It will run for a period if time... and hour... hour 1/2... maybe 1/2 hour then it sputters out and quits. I can restart it, but it dies right away. The little light on my starter switch flashes after this happens. If I let it sit, off, for a LONG time . Like HOURS or over night, the flashing on the switch will stop and it will fire up again... then die again after a period of time.

Load doesn't seem to matter, parked vs. driving doesn't seem to matter. It just runs for some time, then pukes, and may or may not restart. I don't have my auto start turned on or anything.

It "feels" like it might be over heating. It's hot here in Vegas, and I can only imaging what the air trapped between the road.ground and the underside of the RV would be. Anyway, I'm not really sure how to trouble shoot this. There are no temp gauges or lights on the generator to indicate why it shut off. I called my RV dealer and they said "add stable to the gas tank and some sea foam". They think it's bad/stale gas or a gummed up carburetor.

Anyway, I don't think it's the gas, but I suppose it could be. Anyone else have any suggestions?

Thanks,
Brian

I'm betting on the oil OT switch and ended up disconnecting it for good, on our old Gasser, with a Generac 5.5. I would at least do so for troubleshooting purposes, regardless.
You might try giving the air intakes and outlets a good cleaning first and just for making sure of it's validity.

[way2roll]

At what temperature does this happen? Gensets will overheat, especially sitting with no air to cool them on hot days. When it stops there should be a series of blinking lights on the panel, this is the fault code. You can look up the fault in the manual or online for your model.

I had one that did that. The genset was up near the front of the rv right behind the exhaust headers. Poor placement. I ended up installing a heat shield in the front of the bin it sat in as well as installed vented louvers in the bin door. That seemed to fix the issue.

[2manytoyz]

An update:

Even with the new fuel pump, filter, fresh oil and filter, it died after 20 minutes on our last trip. Refused to restart. The fuel pump is on the opposite end from the exhaust, and was cool to the touch. Fuel tank was about 90% full. I drained the bowl into a small cup, and there was 1 oz of fuel, which indicates a full bowl. This failure is not a fuel delivery issue.

We had a number of trips planned in the near future, and Summer is on the way here in FL. I replaced the carburetor, and now it starts and runs like new. The job is pretty straight forward.

I posted a video here if you'd like to see what's involved before deciding if this is a DIY for you: https://youtu.be/DUEthYuKGMk

The replacement carb is about $300 on Amazon: https://amzn.to/2HTRdNM

Sounds expensive, but it does include all the external parts already installed (choke, vacuum solenoid, fuel solenoid, etc.). Really is a plug-n-play swap.

[FireGuard]

Fuel pump.
I had the same symptoms and eventually it wouldn’t start at all.
About $70 on Amazon and about an hour of your time.
A couple of good You tube videos showing how to replace it.
Change the filter also.

[2manytoyz]

Mine did the same thing driving at dusk. I could re-prime it, it would run a minute or two, quit, then repeat. When it was running, it was perfectly smooth.

After much research online, the common consensus is a failing fuel pump. Apparently a very common issue. Often happens 400-500 hours. Mine had close to 600 hours.

The parts are cheap on Amazon, and the repair is easy with basic hand tools. I uploaded a video for a friend on mine being replaced.

Onan 5500W Fuel Pump Replacement

Now it runs for hours, during the peak hours of the day (still hot in FL), while being parked. Purrs along. If mine was a heat issue, likely would have shown up quickly.

[phil-t]

IB853347201 wrote:
I take it this an Onan Marquis 5500? If so, get the manual and read up on trouble codes. Next time this happens, read the trouble codes/flashes on the start switch, and you will have a better idea as to the issue.
Could be low oil, low fuel, etc..

This - that little light flashing is trouble codes. Read up on how to interpret the flashes. I don't recommend just replacing parts until you know what the issue is.
If you have a Cummins Repair Center near you, call and get an appointment for diagnosis. They are very good and will give you the parts required list. From there, you can do the work or have them do it.

[timmac]

PhilipB wrote:
We have same generator in our 5er and similar problems. Ended up we were boiling the fuel. Made a shroud that vents the exhaust side away from the intake. You might try putting a fan under your coach and blow the exhaust side air away and see if that helps.

Yes this is correct, I had to make a shroud under the Gen/exhaust area to push the heat away from the intake and I also plugged up any openings in the Gen compartment to only get cool air thru the intake and this helped a lot, my Gen use to get hot and shut down now it stays running..

[PhilipB]

We have same generator in our 5er and similar problems. Ended up we were boiling the fuel. Made a shroud that vents the exhaust side away from the intake. You might try putting a fan under your coach and blow the exhaust side air away and see if that helps.

[naturist]

Possibilities:
1) low oil
2) marginally clogged fuel filter
3) marginally plugged fuel tank vent
4) hot fuel line resulting in a gas bubble; usually due to poor placement of fuel line or weak fuel pump
5) mis-functioning choke (check for carbon deposits on spark plugs due to rich running)
Those are just my guesses, and not to be taken as a definitive list of possibilities.

[Yosemite_Sam1]

cabranch47 wrote:
Could it possibly be as simple as a closed or clogged vent on the feul tank?

Or weak spring on the choke for starting.

Mine detached from the snag and keeps on going back to "close" after being jarred back by the vibrations and running for sometime.

[cabranch47]

Could it possibly be as simple as a closed or clogged vent on the feul tank?

[puddleduck]

IB853347201 wrote:
I take it this an Onan Marquis 5500? If so, get the manual and read up on trouble codes. Next time this happens, read the trouble codes/flashes on the start switch, and you will have a better idea as to the issue.
Could be low oil, low fuel, etc..

x2

[IB853347201]

I take it this an Onan Marquis 5500? If so, get the manual and read up on trouble codes. Next time this happens, read the trouble codes/flashes on the start switch, and you will have a better idea as to the issue.
Could be low oil, low fuel, etc..

[Ranger_Smith]

Do a search. There are a ton of replies with people having the same problem. When that happens it is generally the fuel pump or low oil. If the oil is not low purchase a fuel pump and that will generally take care of the issue. I think you can even get the pump on Amazon.