Onan 5500 quits when over 95 degrees

Edonabike · 06-14-2019, 07:56 PM

We purchases a Jayco Precept in August 2018 with a 5500 Onan generator. Our first trip out west we found the generator would cut off when driving if the heat outside exceeded mid 90's (after 20 to 30 minutes it will restart and run for about 15 minutes). Took it to Cummings and they put on a heat shield to help the air intake draw cooler air. The day I picked it up the generator quit within 15 minutes after leaving Cummings. By the time we took it back in it was cooler fall weather and they could not duplicate the problem. On Memorial day it was mid 90's and again it cut off 7 times during a 185 mile trip. (the return trip was in the 80's and no problem)

Jayco was not at all helpful when I tried to find out it other people have had this problem and what was the fix. It is now at Cummings but they said they would not drive it. Without the added heat from the engine and road it will not duplicate the problem, so I don't expect any solution from them.

Has anyone experienced this and how did you correct the problem?

MikeThompson · 06-14-2019, 08:16 PM

What's the longest it's run with lower temps? When we first got our 2018 Precept, the generator would run for a few minutes and then shut down. I found the fuel hose had been connected to the tank with a zip tie. It had come loose and the hose had twisted and gotten a kink in it which had restricted the fuel flow. I connected the hose to the tank with a metal clamp and haven't had a problem since. Check your fuel line for any problems.

WinnieView · 06-14-2019, 08:54 PM

Replace the fuel pump, it's a known problem with the 5500;

https://www.amazon.com/Electric-Repl.../dp/B07CVWX3VB

Allen_C · 06-15-2019, 07:49 AM

It could be a "too hot to run" issue as you thought. We drove out west along The southern States two summers ago and experienced similar things when the temps were above 95°. One solution I've seen is adding louvers on the door covering the generator so additional air flows. I believe someone posted a video on doing that in irv2

Duke4857 · 06-15-2019, 09:42 AM

Quote:

Originally Posted by Allen_C

It could be a "too hot to run" issue as you thought. We drove out west along The southern States two summers ago and experienced similar things when the temps were above 95°. One solution I've seen is adding louvers on the door covering the generator so additional air flows. I believe someone posted a video on doing that in irv2

Thank you for pointing out another camping forum. Might be another place to find info. I did not join, but will one of these days.

Edonabike · 06-15-2019, 02:12 PM

Thanks everyone.
The generator has no problems when parked or when driving if the outdoor temp is under 90 degrees. It will run for hours and never shut down.

I like the louvers on the door idea but will see what Cummings comes up with.
The generator compartment has plenty of room all around it so I know it is not restricted air flow. However when you look at the back side (toward the drive shaft) is is completely open. I suspect with the added heat from the engine and road are the main cause of the problem.

hawkster · 06-16-2019, 05:30 AM

Concerning the louvers. Mine came from factory without green door on generator. My basement door warped. That was a jayco cluster to get fixed. The most I ran it was one hour every month as recommended. So with louvers another problem might be created.

MikeThompson · 06-16-2019, 08:05 AM

Trace your fuel line all the way back to the tank and see if it gets close to the exhaust or anything that will add heat. It sounds like you may be getting a vapor lock somewhere. If that's the case you can insulate the line or move it away from the heat source.

Edonabike · 06-16-2019, 08:05 PM

Mike:
I hope Cummings looked at that but it is a great thought. Will check it out when i get it back from Cumming. Hopefully this next week.
Thanks

Allen_C · 06-17-2019, 06:53 AM

Quote:

Originally Posted by hawkster

Concerning the louvers. Mine came from factory without green door on generator. My basement door warped. That was a jayco cluster to get fixed. The most I ran it was one hour every month as recommended. So with louvers another problem might be created.

Not saying it's impossible but improbable. That green door on the generator keeps heat away from the basement door. Adding louvers to the basement door will just help get more air to the green door and the generator.

Dbrown · 06-17-2019, 11:58 AM

Try run it with the door open when its 95deg to see if it is a heat related issue.

JesseS · 06-24-2019, 10:15 PM

I dont't have that model, but my Onan 4K did the same thing to me, over 95º or 100º it would shut down and show an overheat code. I ran it with the door open and it was fine, seems the genset door was only 2" from the compartment door and restricted the air flow, or fed hot engine air into the unit. I cut a 9"X9" hole in the compartment door directly in front of the air inlet on the genset and installed a metal mesh insert, problem solved.

edatlanta · 06-25-2019, 03:58 AM

The 5500 has 100% of it's out of the bottom of the unit so leaving the access door open or closed has zero impact.

JesseS · 06-25-2019, 08:32 AM

Quote:

Originally Posted by edatlanta

The 5500 has 100% of it's out of the bottom of the unit so leaving the access door open or closed has zero impact.

Correct, looking at the spec sheet it shows all inlet and exhaust air ports on the bottom. It does seem strange to have the cool air inlet and hot air outlet so close together.

Forelyndogs · 06-29-2019, 01:54 PM

We had this problem for years with both our Winnie and the current Jayco. We haven't fixed the problem 100% but it is much better than it was. We were told to run the unit under load for one hour once a month. The only way to really get it under load is to turn the a/c on. We have a heat pump (cools or heats) so we can run the unit any time of the year. We learned a few things that didn't make the unit work better but did explain stuff. The generator will not start or will stop running if there is less than 1/4 tank of gas in the main fuel tank. I assumed the unit was fuel injected and therefore had not carburetor float. Not true, my 2014 model is carbureted and the float doesn't work when climbing a fairly steep hill. We live in the desert west and the generator is expected to run in 100 plus degree weather and "usually" does. Never had the unit fail while stationary, only when driving.

Jacobsnc · 06-29-2019, 02:03 PM

Ours on a 2015 Precept will usually run fine on the road in hot weather, but if we pull into a rest area or camp ground it will stop. Parked in a Walmart lot once for two days, had a tire issue, generator ran non stop for 48 hours in +95 degree heat. There was a stiff wind so I suspect it helped cool the generator. I don't believe there is a hot engine shut down sensor on these units.

trento · 06-29-2019, 05:18 PM

Quote:

Originally Posted by Edonabike

We purchases a Jayco Precept in August 2018 with a 5500 Onan generator. Our first trip out west we found the generator would cut off when driving if the heat outside exceeded mid 90's (after 20 to 30 minutes it will restart and run for about 15 minutes). Took it to Cummings and they put on a heat shield to help the air intake draw cooler air. The day I picked it up the generator quit within 15 minutes after leaving Cummings. By the time we took it back in it was cooler fall weather and they could not duplicate the problem. On Memorial day it was mid 90's and again it cut off 7 times during a 185 mile trip. (the return trip was in the 80's and no problem)

Jayco was not at all helpful when I tried to find out it other people have had this problem and what was the fix. It is now at Cummings but they said they would not drive it. Without the added heat from the engine and road it will not duplicate the problem, so I don't expect any solution from them.

Has anyone experienced this and how did you correct the problem?

could be a heat protection switch on the lube oil.made to shut down the engine so it doesnt bake.i had the same thing in a boat i owned.

Johnynorthland · 06-29-2019, 09:38 PM

Please Let us know what finally was the fix. We’ve Owned 3 rv’s with onan gens, Had one gen with a bad carburetor that was replaced another one that had a low oil cutoff and kept stalling and wouldn’t restart. It just needed oil! I should have checked the oil but RV was new and had under 20 hours on the gen! I guess dealer prep dropped the ball and never checked the fluids! Imagine that!

putz · 06-30-2019, 01:12 PM

I had a problem with my older Motorhome doing the same thing. Onan run the unit for hours with no problem. When driving junk in the tank floated around and blocked the fuel line. Took the fuel line off and blew air towards the tank it apparently pushed out some junk that was apparently blocking the fuel line in the tank. Could be your unit is just not getting enough fuel. Worked for awhile then clogged up again. Its a drop the fuel tank repair. So I bought a new RV.

Edonabike · 07-02-2019, 08:27 AM

Cummings put a new carburetor on the unit. It ran for 3 hours during a drive on Sunday in low 90's. It was hot enough to to cause the problem because my tire temperatures were running 115 to 120 degrees, which is normally hot enough to see the problem. Oddly it turned only once and that was after our arrival while driving through the campground, which was shaded cooler roads so not sure if that was the same issue or some other problem. We will see this weekend on the trip home.

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