2021 Raptor 356 - Generator

[cw raptor]

I have a 2021 Raptor 356 that we purchased new in 2022. The Onan 5500 gas generator has been an issue almost from day one. A new carburetor was installed, and the generator worked fine for a few months when test running it each month for 30 minutes.

It now runs for about 10 minutes then shuts down with an error code "36". Appears to be fuel related. I have traced the lines and it appears the rear tank is the generator tank. However, the fuel gauges appear to be mismarked/wired. When I pump fuel out of the "toy" tank the generator fuel gauge drops.

I have disconnected the line at the carb and the prime pump seems to pump well (although I did get some debris out of the line).

There is a black plastic box next to the fuel tank that has what appears to be fuel lines (3) running to it. At least one goes nowhere and looks like some type of vent. The other two run to the topside of the tank near as I can tell without dropping the tank.

There are two lines coming from the other side of the tank and run to the front of the trailer where the generator is.

I did notice some of the lines in the run are slightly pinched. I discounted them as the issue as the Generator has run properly from time to time.

Any thoughts or suggestions would be appreciated.

Thanks

[Raptor 429]

From the info given my first guess would be debris in the tank and or gas lines.

If the carb clean fixed it then running the generator triggered the problem again my guess is the carb is gummed up again.

Another carb clean and an inline fuel filter as close to the generator as possible would be an inexpensive place to start.

If you install a fuel filter please shoot a picture back. I've been meaning to add one to ours.

We have had numerous faults but never one that kept it from running. I typically remote start ours when we get close to our destination. It gets the ac turned on and any problems worked out while we are still within town range.

Also note never use or let ethenol sit in those tanks. If you run a search for ethenol free gas you will usually find a station within range.

[cw raptor]

Thanks!! Very helpful, I will start there!

[Philip]

The generator should have a fuel filter directly underneath it. This should catch anything that's able to travel from the fuel tank. Might be clogged. This is a cheap and easy replacement.

We had trouble with ours shutting off. It's a 2013 310. We found that it was boiling the fuel. I think this was due to the drop frame. Space between the ground was less so the heat from genny exhaust was boiling fuel coming in.

I don't think you have a drop frame on yours.

[cw raptor]

I am not sure what a drop frame is but the fuel lines cross over to the opposite side of the trailer from the generator exhaust pipe.

Thanks for the reply!

[Raptor 429]

Back checking in:

According to the all knowing internet, code 36 is the generator shutting down without being commanded to do so. This site has 4 steps to check. Starts with fuel and carb so looks like your on the right track.

Good luck!

https://www.rvandplaya.com/onan-generator-fault-code-36/

[cw raptor]

Thank you!!

[Raptor 429]

Here is the link to the owners manual. It's only a matter of time before I'm sure I'll need to find this. If the manual is accurate it looks like there is a float bowl drain. Also the fuel filter is on the generator and looks like one of those old ones you can blow through to see if they are clogged.

https://www.cummins.com/sites/default/files/rv-manuals/A035D009.pdf

[cw raptor]

Thanks all for the common sense advise. Looks like a fuel filter fixed it!! I will update if another problem comes up.

[cw raptor]

Fuel filter did not fix it. Since I added a clear filter, I could see what was happening to the flow. The generator would run for a long time (should have timed it, easily 30 minutes). The fuel level in the filter would begin to decrease until the unit was starved for fuel. I found several hangers that were pinching the lines and released them. Things got better but there was air getting into the line. Found a leak in the line at one of the pinch points, and I am fixing it now.

[cw raptor]

Dang problem is back. I cannot find another leak. Anyone know if a bad fuel pump will allow air into the line. I can see air bubble coming into the filter as the pump is running.

[Raptor Dave]

Welcome to the Onan owners club.
Similar situation for us on a brand new 2023 unit. (gen says 2022 on it)
I have googled this problem to no end. (still look every now and then)
There are a few very interesting youtube people who claim they have solved the mystery.
According to the ones I have looked at (that seem like reputable posters) their claim is if it is "over full" of oil it will cause the shut down and a 36 error code to appear.
Go to youtube and search "onan generator won't stay running" and you'll have plenty to look at that may help.

My disclaimer..... I have not run mine since this has happened and I have returned home in AZ. It is still pretty hot in the valley so I have been waiting for a cool down to check mine and test run it under a load and see what happens. If I still have the shut down problem I will try the lowering the oil level trick and see what happens.
I will say this... when I pulled the dipstick on mine the oil was so full it ran out over the threads.

Also I would also say sticking to their guide that suggests you run the generators once a month for 10-15 minutes is probably good.
I also run a product called seafoam in my gas tank to help keep from gumming and clean the varnish out.

[cw raptor]

Thank you sir. Very Frustrating.

[Raptor Dave]

GL

Let us know how it turns out.


Regards Dave

[Raptor Dave]

Were you able to get your gen figured out?

We just got ours back from the Cummins dealer here in the east valley.
After several calls to Cummins tech support and talking with a gentleman there named Jacob we ran out of options and after finding out I have a 3 year warranty on the gen he hooked me up with the local shop.
Very pleased so far...I took the trailer in and dropped it off Wed morning and they called today, Friday and said it was fixed under warranty. (2 year parts and labor...3rd year parts only)
New carb and fuel pump. The tech there told us they have seen a rash of bad ones coming in over the last year or so. Some parts inside disintegrating and plugging up the fuel system. Brand new gen would start in the morning and run for a short period, shut down with a 36 code and then act like it was starved for fuel.
All good so far!

On to the next....

Regards Dave