Onan 5500 quits when over 95 degrees

[Foretm]

Our first trip after the work from Cummins seemed to go well, but it wasn't as hot as it was the other couple times. I ran it all the way to destin and we sat in a walmart parking lot for an hour while I took a conference call with work and no issues. On the way home when we stopped for lunch, it did shutoww but we were at 1/4 tank, so I tend to think that was the culprit in that case. so heading out tomorrow and will run it all the way there and see what happens when we stop for any length of time.

[RoyB]

I have owned a brand new expensive 36A for two months now and have not been able to use it. The generator will not run along with the V10 engine running and temps over 90. We live in Ok and the temps are over 90 much of the time. The thing is a sauna, completely unbearable for any distance. I have had it at Cummings, they have added the "fix" heat shield and it died before I got a mile away from their yard. They have exhausted their ideas of what to do. I ran experiments for several days, used up an entire 80 gal fuel tank and put 125 hours on the generator. I now have detailed charts of the interaction between the temperature, V10 engine running and the generator running. At 90 and above the generator will not run with the V10 engine running for more than 30-45 minutes whether on the road or sitting in my driveway. But, if I run the generator out of a 5 gallon gas can on the driveway then it will run for 10 hours with the V10 engine running in 95+ temperatures. The generator will run for 10 hours out of the motorhome fuel tank if the V10 stays off. So, there is a fuel supply problem, but only if the V10 engine is running. Okay, so I got new fuel injection hose and ran a new fuel line from the vehicle tank to the generator with exactly the same results. The problem is some kind of design fault by Jayco, the generator was mounted to close to the V10 motor or transmission or the fuel uptake in the tank is too close to the V10 uptake and robs the generator uptake of fuel. I just know that I had to buy 8 airline tickets to Orlando, Fl for next week because the Precept 36A sitting in my driveway is worthless for traveling. Sorry, but I'm not real happy with Jayco right now.

[hawkster]

RoyB, probably not the same situation as you but we rarely use the gen. When traveling in 90+ I close a curtain that I mounted behind the elevator bed. This keeps the dash a.c. up front and not trying to cool the whole motorhome. We only have two adults and a dog. When we stop for lunch I turn on the gen to keep things cool. Have you tried insulating the new fuel line you installed?

[Johnynorthland]

Hopefully your rig is financed? I would call the lender tell them you don’t want it anymore and Telly them why! I use to work for an auto service dealer and have herd of people doing this. It puts a fire under their but!

[JimD]

In the old vapor lock days I believe one of the fixes was to have the fuel pump push instead of pull. They would mount the pump at the tank and have it pressurize the fuel line rather than trying to suck overheated vapors through it. I don't know how your genny is plumbed but my son's 5500 in his Weekend Warrior has the pump mounted at the genny.

If it were me, and I suspected that the actual unit was running too hot in its enclosure, I would try adding some fans to get extra air movement. Does it overheat with the access door open? There are some nice radiator fans that move a lot of air. Maybe it could be mounted underneath just to get some air movement.

Being able to duplicate the problem is the best thing going for you, Intermittent problems can be a bear to fix.

[RoyB]

Hawkster - I bought a bunk house with 9 seat belts and 10 beds so that our family could travel together. Being limited to two passengers negates the whole point of a bunkhouse. Good idea about the blanket, I've used that trick in several aircraft I ferried across the ocean. I will keep that in mind but don't really want to keep this MH if I'm going to be limited. I have not tried insulating the fuel line and am reluctant to invest any more time or money in a 6 figure investment that does not serve it's primary function. If Jayco does not respond with effective solution then they can have it back.

[RoyB]

My wife and I are retired and have been saving for 20 years to buy a motor home so we were able to pay cash. But I have a lawyer who is good at lighting fires also.Thanks.

[RoyB]

Good thinking but Onan locates the pump at the generator for a couple of reasons. One is it has to have power from the logic circuit board so power would have to be run the length of the fuel line to the pump. Two a pusher pump would create a fire hazard if the fuel line were compromised at any point fuel would be squirting into unknown places. I am reluctant to do any more at this point either Jayco is going to find the cure or they are going to own it.

I have pretty much ruled out the overheating problem. Remember I can run the generator out of a gas can sitting underneath it with the V10 motor running and temps over 90. So the generator itself is not overheating. In every test of more than a hundred the failure code from the generator has been a 3,6 which decodes to a fuel insufficiency.

You are right, I was a maintenance officer and military test pilot for 30 years and the scariest problems are random. That's why I spent a few hundred dollars and many hours finding the pattern that causes the failure which pretty much takes Cumming out of the solution. Its a fuel supply problem in the way Jayco installed and fueled the generator.

[redfernj]

Darn...you all have me worried...we just bought our Precept 3 weeks ago with intention to travel from west coast to midwest in spring/summer for dog shows and vacation combined. Will need reliable AC in coach while on the road...and I have no mechanical know how...ughhh

[Johnynorthland]

I try not to worry when it comes to the RV I just try and prepare for any possible scenario that could happen. If I relied heavy on my generator I would carry a spare. We don’t do a lot of dry camping and don’t usually run it when traveling but I do maintain it as a backup feature and I have a 2nd generator in my garage.

Just for those reasons above I think solar is a great idea. I had solar on my 2nd RV and miss it a lot!

[Edonabike]

After 4 trips to Cummings where they replaced the carburetor, and added a heat deflector to the air intake, the problem still exists. The motorhome is currently at the Jayco Manufacturing facility. They seemed to be confident that they had a solution to the problem, but we will not know until next summer when it gets hot again. I would suggest if you do experience the problem you contact Jayco for the solution. I believe it is a design problem and not the generator. I am not sure where the generator is placed on your unit, but if it is not in the front compartment just behind the engine you may not experience the issue.

[Edonabike]

RoyB - I recalled your post and your frustration with your Onan seemed as elevated as mine. Thought I would send you this FYI in case it could help you. I dropped off our unit at Jayco factory in Middlebury IN in Oct. Got it back in Dec and they actually manufactured a air scope that is mounted under the generator with the intake facing the side of the motorhome. Apparently they had been working with Onan on a solution for the design problem. I will not know if this works until summer but I am thinking it may be a good solution.

[RoyB]

Edonabike - Thanks for pursuing this and I so hope the fix works! Please advise as soon as you can establish its success.

[JudyB]

We are going there in May...let me know if it worked. If so, I may have them work ours in.

[Steve1152]

can you post some pictures so i can see what they did. thanks , sure hope it works.

[Edonabike]

Here are a couple photos. Hard to see the one from outside but the one under the unit should show how it works. It does lower your ground clearance but no lower than the generator exhaust pipe.

[RoyB]

Do you have any update on the success of this modification? We are hoping to be able to use our MH this summer.

[Forelyndogs]

Unfortunately, with Covid-19 making a mess of travel plans, we have not been able to test any fixes to this problem. It is important to remember those two points that with between 1/3 and 1/4 tank of gas the generator will not run while driving. It doesn't seem to care while stationary. Second, steep inclines cause carburetor problems. Funny, autos more or less solved that problem before the advent of fuel injection, why can't the generator? It doesn't look like we will be traveling before fall. Hard to believe we have spent so much time at home.

[Edonabike]

It takes at least a 90 degree plus day for the problem to show up. So far we have not had that temperature to test it. Our spring travel plans were to Florida state parks and they were canceled so not sure when we will get to test it.

[JudyB]

I can tell you that even though I pulled off a point of oil, the problem over 90 degrees still exists for us with our 4000 Oman. We are on the road, but leaving Las Vegas in the heat could only run 10 minutes without stopping. It’s been suggested that the ethanol in gas has ruined our generator.... been resorting to clear gas, non ethanol. Below 90..... I think we could run forever!!