Onan 5500 Generator Dies

[Campingsxs85]

My Wife and I just purchased a new 2022 Alliance Valor 42V15 with a Onan 5500 Generator onboard. Yes, it is a brand new 2022 we picked it up in Billings, MT. We live in the Midwest so it's hot and humid a majority of the summer. We are not new to camping this is actually 4th camper but it is our 1st Toy hauler and since we have purchased it back in June we have pulled it several destinations totaling roughly 4,000 miles in just a few months. We have aspirations of Boondocking in the Mountains and riding our SXS out of a remote location. But until I can keep the Generator running I don't feel comfortable taking that leap yet until I can keep it running. Currently the Generator has roughly 35hrs on it and the majority of the hours are on it from troubleshooting. It will run anywhere from 2-3hrs in a shop setting right now. When we first got the camper 1/2-1hr might of been about it then it would shut down.

So far what I have done to the unit is the first break-in oil change at roughly 20hrs. I have put a new fuel pump on the Onan 5500 with a new fuel filter. I have added a second Low Pressure fuel pump next to the tank to supply the fuel pump on the Generator unit which has helped tremendously. I added the titanium spark plug wire wrap around the fuel line in the Generator compartment to try to keep the heat down on the fuel line (Vapor Lock). I have wrapped the fuel pump under the unit with exhaust wrap to try to keep the heat off of the fuel pump to keep it from shutting down.

I have tried to run this unit while driving down the road and it seems to me like about 2 hours is the most it has ran. Our last trip was to Galveston, Tx a couple weeks ago and it was upper 90's low 100's the entire trip and we could not keep the unit running. Coming home the last day it was considerably cooler probably 75 degrees and it ran for about 4.5hrs with 2 A/C's on with no problems. Which leads me to believe that this entire issue is a Hot Air Recirculation issue since the cool air intake and hot air exhaust is all on the bottom of the unit.

Has anyone has this same problem with the Valor or any other 5th wheel camper for that matter? I think my next step is. I am going to Duct the Hot Air Discharge out the same side as the generators exhaust (Driver Side) to try and get the hot air out from under the camper to try to prevent hot air from entering back into the cool air side.
Any thoughts or suggestions would be appreciated. Thanks!

 

[BryanValRox]

My Wife and I just purchased a new 2022 Alliance Valor 42V15 with a Onan 5500 Generator onboard. Yes, it is a brand new 2022 we picked it up in Billings, MT. We live in the Midwest so it's hot and humid a majority of the summer. We are not new to camping this is actually 4th camper but it is our 1st Toy hauler and since we have purchased it back in June we have pulled it several destinations totaling roughly 4,000 miles in just a few months. We have aspirations of Boondocking in the Mountains and riding our SXS out of a remote location. But until I can keep the Generator running I don't feel comfortable taking that leap yet until I can keep it running. Currently the Generator has roughly 35hrs on it and the majority of the hours are on it from troubleshooting. It will run anywhere from 2-3hrs in a shop setting right now. When we first got the camper 1/2-1hr might of been about it then it would shut down.

So far what I have done to the unit is the first break-in oil change at roughly 20hrs. I have put a new fuel pump on the Onan 5500 with a new fuel filter. I have added a second Low Pressure fuel pump next to the tank to supply the fuel pump on the Generator unit which has helped tremendously. I added the titanium spark plug wire wrap around the fuel line in the Generator compartment to try to keep the heat down on the fuel line (Vapor Lock). I have wrapped the fuel pump under the unit with exhaust wrap to try to keep the heat off of the fuel pump to keep it from shutting down.

I have tried to run this unit while driving down the road and it seems to me like about 2 hours is the most it has ran. Our last trip was to Galveston, Tx a couple weeks ago and it was upper 90's low 100's the entire trip and we could not keep the unit running. Coming home the last day it was considerably cooler probably 75 degrees and it ran for about 4.5hrs with 2 A/C's on with no problems. Which leads me to believe that this entire issue is a Hot Air Recirculation issue since the cool air intake and hot air exhaust is all on the bottom of the unit.

Has anyone has this same problem with the Valor or any other 5th wheel camper for that matter? I think my next step is. I am going to Duct the Hot Air Discharge out the same side as the generators exhaust (Driver Side) to try and get the hot air out from under the camper to try to prevent hot air from entering back into the cool air side.
Any thoughts or suggestions would be appreciated. Thanks!

Hi folks,
Are your experiencing any codes? This would be indicated by flashing lights on the start stop switch.
I would suggest that you start by reviewing the Onan Installation manual.
Link Below.

Generator - Cummins-Onan, Installation Manual | Alliance RV

Installation Manual for Cummins-Onan HJAA 5.5 KW Generator Version: A035D005 Issue 9-07-2016

alliancerv.com

Generally speaking, not just specific to Alliance, there have been numerous issues reported with restricted fuel lines. I would suggest that you inspect for sharp bends, kinks, tight “P” clamps that could be restricting your fuel flow.
Onan has actually published a bulletin on this issue, also numerous issue with vapor lock conditions have been reported, prompting another bulletin recommending fuel line insulation kits for the entire fuel system. There is also a specific carburetor insulation kit to help prevent the vapor locking. They even call out the addition of another higher psi fuel pump to provide margin against this vapor locking.
Also, regarding air flow issues, with in the manual link above, there are some key points that need followed.
Specifically, the mouse holes, which are half round cuts outs in the alum. base need taped/ blocked off when installed on a flat floor installation. There are 3 of them. One in the front, one in the side and one on the rear. Also any gaps that are around the base and compartment floor intersection need to be taped/sealed off. You don’t want to see daylight through the floor.
There is also a a air recirculation test called out in the manual to check for the recirculation you suspect.
Onan offers numerous duct options to help prevent hot air recirculating.
Sounds, like you are experiencing you issue both static and while towing. Things to remember you need at least 12 inches on clearance underneath to help prevent air recirculation. Also don’t forget that that your tow vehicle’s exhaust could be contributing to the issue, by having the hot exhaust drawn into the intake cooling air that the genset needs. This also adds heat under the coach that can lead to vapor locking.
At the end of the day, I would review the installation manual and see how your installation compares to the guidelines.
Next, I would contact your local Cummins Distributor and provide them your set serial number and ask them to research bulletins that apply to your set(there are several on these topics) specific to fault code 36, vapor locking and hot air recirculating.
If your local branch can’t assist, I would recommend contacting the Cummins Elkhart Branch, as they support many of the the OEM’s. They should be quite familiar with the bulletin’s and should be able to supply you with part numbers and pricing for some of the insulation kits and baffles that should help improve your concerns. Be sure to ask the Cummins location to research your set s/n on QSOL(Quickserve Online) and they should be able to locate the bulletins that I am referencing.

 

[Campingsxs85]

Thank you for the detailed response. The Fault Code is always 36 and I usually go open the drain on the carb and it is basically empty. Which lead me to believe it is a "vapor lock" or fuel delivery issue. I will try to get a Hot Air Recirc. Test done tonight to see what kind of Temp difference there is. I did look at the P clamps once and didn't see anything obvious that was pinching. I need to look on top of the fuel tank and check the fuel line.

 

[HCL]

We ran into the same issue on our 36V11.
Loosen your fuel cap when you start the gen set and see if that helps, if it does, replace fuel cap.
It's a pretty long run for that little pump to pull fuel from the tank to the gen set so does not take much of an air restriction to stop the fuel flow.
Hope this helps.
Mike

 

[Campingsxs85]

I actually installed a second pump with the same output psi as the Onan pump on the frame rail right next to the tank to help with the fuel delivery. I thought the same thing that it was an awful long ways to pull fuel. I have not tried loosening the fuel cap though.
Thanks Mike!

 

[HCL]

What I found is the cap does not allow enough airflow for pump to pull fuel to gen set and causes a vapor lock and code 36 unless cap is loosened.
A new working cap will most likely solve your issue.
Mike

 

[Hotrodjohn]

I was at Cordova dragway and mine ran for three days. I have the EC-AGS+ on mine so I can start and stop the generator automatically at a set temp to run the ac and not run the genny full time. Three days it worked perfectly. I did run it straight for 6 hours once also while smoking ribs. Hope you find it and get her running cause it’s awesome

 

[Trumpforpres]

I actually installed a second pump with the same output psi as the Onan pump on the frame rail right next to the tank to help with the fuel delivery. I thought the same thing that it was an awful long ways to pull fuel. I have not tried loosening the fuel cap though.
Thanks Mike!

Mike, I’m curious how you added the second fuel pump. How are you powering it so that it only runs when the priming button is used on the generator?

 

[Campingsxs85]

So I am finally getting around to providing an update. After going down the rabbit hole and more research/testing. I installed a hot air deflector that I purchased directly from Cummins that fit out rig. After performing a Hot Air Recirculation test described above by (BryanValRox). The deflector was factory backordered and by the time I got the deflector camping season was wrapping up and the outside air temps were dramatically cooling off. I have run the unit in the shop with 2 A/Cs on for 4-5+hours with no issues so far but again it’s cold out now so I guess I will have to wait until next summer to run it though it’s paces.