Community Forums

smartguy · 12-07-2021, 02:50 PM

I have an Onan Marquis Gold 5500 and it runs for about 5 minutes and shuts down. I have changed the oil and filter. I went to an RV repair here in Yuma and was told that it was the carburetor. I ordered a new carburetor and installed it and used an inline clear gas filter to see if it was still getting gas. I started it and it ran great but after about 5 minutes it shut down again. I checked the codes and it gave me a 36 code and it was to tell me that the unit had shut down. Go figure.

Anyone familiar with this kind of problem and ANY suggestions that could help, would be my next champion!!!
Thanks!!

DonR · 12-07-2021, 02:57 PM

Mine would do that, as soon as the generator warmed up it would quit.
turned out to be a bad fuel pump.
Easy to change out.

David 70 · 12-07-2021, 02:58 PM

Mine was doing the same thing after I got it. Ended up being the fuel pump, it would get hot and quit. I installed an inline fuel filter also but kept having problems and kept watching the inline filter. I noticed the filter never got full so I removed it and all was well for that part. It had sat for several years before I got it and the carb was gummy and no rebuild to it so a new carb was next. I still have problems when I first start it as it wants to search. I find if I shut it off after a couple minutes and restart it it runs better but still not the wayu it should. It sometimes think it's just an Onan thing.

donr103 · 12-07-2021, 03:10 PM

How old is gen?... guess if don't know... also when was last time fuel pump changed?
Have you cleaned the armature slip rings ?
Have you pulled fuel line at carb and made sure great stream ..?

1st.. don't throw away old carb.. they are easily cleaned.. I suggest you look on you tube KEVIN CAUDILL.. he shows step by step how to clean carb..

Never take onan gen to any shop... they have no idea of what to fix.. if you find one that does.. please let us know..

I have never had any luck with any authorized shop.. it seems they just have no clue how to fix..
These gens are bullet proof.. so roll up sleeves and sit back and read...
I and many members here have so many tips and repair opinions posted about onan 5500 and others..
So search my name
Good luck and let us know what you did and maybe better members then me will help you

fatsurf · 12-07-2021, 06:12 PM

They are really sensitive to oil level, suggest making some adjustments to that before anything else.

daddude1218 · 12-07-2021, 07:08 PM

This time last year mine would run and then die after 10 minutes.Replaced in line filter and fuel pump.Bench tested pump and was working as it should. Primed and ran for a short time and then stopped. I then decided to pull off fuel line before pump and no fuel leaking out of hose. I checked the fuel line back to tank and it was corroded with rust. I knew then that there was a pinhole along the line. Took MH to truck shop and they replaced line and said generator ran good off of a gallon can hook up while they were fabricating fuel line.Started my 2500 mile trip and it ran enough to cook a dinner or two and then had problems again. It's now at a new shop and they called and said carb bad and are replacing it. This genny has about 50 or less hrs. The MH was bought new in 2015.It's hard to find Onan repair shop in my area. CHECK THAT LINE TO TANK NEXT TIME

CamJam1 · 12-07-2021, 07:30 PM

The "36" code is a catch all code, but usually means a fuel problem. Mine was doing the same thing and replacing the carburetor fixed it, but since you have already done that I would replace the fuel pump. Don't get a high pressure pump. 3.5-4 psi works best with gas Onans. Plenty of pumps on Amazon and E-Bay will work, but most are made in China. I bought this one, Made in the USA for a few dollars more and it's working well.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Could definitely be a crack in the fuel line too. I chased my tail for months, including changing fuel lines and even the pickup location in the fuel tank before I found out it was the carburetor.

High Road Travelers · 12-07-2021, 09:27 PM

On mine that would run for a while, then shut off, a fuel pump replacement fixed it and it has run great ever since.
As others have said there are a number of issues that can happen with generators (and most shops do not have a clue). From what I have seen on this forum, it is usually a fuel issue, but not always.
Thanks,

George Schweikle · 12-08-2021, 07:11 AM

X2. I had the same issue on an Onan 4000 and chased a lot of other "cures" before finally replacing the fuel pump. Urban legend has it that the Onan fuel pump can sometime be marginal even in a new generator.

Quote:

Originally Posted by DonR

Mine would do that, as soon as the generator warmed up it would quit.
turned out to be a bad fuel pump.
Easy to change out.

mr.tommy · 12-08-2021, 07:34 AM

95% of the things you need to do to keep your generator running top notch, you can do yourself instead of taking it to a shop. And it's not that difficult to learn.

Sometime ago, I found a great 3 part series on youtube titled "Onan Marquis Gold 5500 Master Class". It's free and it covers just about everything you need to know on how to properly maintain a Onan Marquis Gold 5500, service schedules, replacing parts, proper exercising, slip rings and more. It also covers some trouble shooting tips.

If you're not sure how to service your RV Gas Generator and would like to learn, this video series is for you.
https://www.youtube.com/playlist?lis...cn1LTAzgImKgH0

cjd10 · 12-08-2021, 09:12 AM

Mine did that last month on a trip to Illinois. Bad fuel pump
Bought a cheap one off Amazon and it leaked. Ended up paying more for an OEM from Onan. Fairley easy install. Hardest part was getting the old fuel lines off

smartguy · 12-09-2021, 11:55 AM

Thanks to all of you for taking time to offer your solutions for my problem. I have taken that advise and ordered a fuel pump and I'm now confident that this will solve my issue.

Again, many thanks to you all!!!!!