Onan Generator in Class A possible overheat and overuse

[rcarpe06]

Hi, We have a 2014 Fleetwood Bounder Classic 34B Gasser with an Onan 5500 Generator. Last year, we only took short 2 to 3 hour trips in the fall when we got it. I would run the generator so that I could use the house A/C and cool the inside down.

Took our first long trip last week and coming back from Florida (90 degrees) I ran the generator at first as usual. After about 4 hours of continuous use and both A/C units running nonstop, the generator cut off and threw a fault code of 36.

After resetting the alert and letting the unit cool down for a half hour while driving, I was then able to start it back up and run it again for a few hours.

Am I pushing the unit too hard or should it be able to run continuously without interruption?

Also, on the way down to Florida, I let it run for several hours while driving for the day to power TV's and other small electronics. The A/C hardly kicked until I got close to the end of the day in Georgia.

RC

[rcarpe06]

blawless wrote:
Could be as simple as while driving down the road you let your fuel gauge go below 1/4 tank. The geneator fuel inlet will not suck gas below a 1/4 tank as a safety feature. If between 1/4 and 1/2 and you were going up hill or down hill on a long grade it will also be below the genny inlet tube in the gas tank and cause the same problem.

At first I thought this might be the problem, but it shut down right away even after a refuel with a full tank. But then after driving for a half hour, I was able to start it and keep it running again. The unit is extremely hot when it shuts down. You can't even touch the air cleaner clips, etc. without gloves or you will burn yourself. It's just wierd, I ran it for 16 hours straight going down to Florida, but could only run it for 3 - 4 hours at a time coming back to Michigan.

[ArchHoagland]

My Onan 5500 will shutdown on 95 degree days when I'm stopped.

If I'm moving it will stay on until about 100 degrees and then shut down too.

Varies a bit depending on wind direction ,etc.

[willald]

blawless wrote:
Could be as simple as while driving down the road you let your fuel gauge go below 1/4 tank. The geneator fuel inlet will not suck gas below a 1/4 tank as a safety feature. If between 1/4 and 1/2 and you were going up hill or down hill on a long grade it will also be below the genny inlet tube in the gas tank and cause the same problem.

I'm betting this is the cause. Original poster said that this happened when they took their first real long trip with it, so I bet they got down close to or below 1/4 of a tank of fuel, resulting in the generator running dry on fuel.

I know why they are built that way, but I still don't like the fact that generator can only run on first 3/4 of a tank of fuel. When traveling in hot weather where you need your generator and air conditioners running, it severely limits your range between fill-ups when you lose your generator and air conditioners at 1/4 of a tank. I've thought a few times about trying to change this, and make the generator fuel pickup feed from ENTIRE fuel tank, not just the first 3/4 (anyone ever done that?)

Glad someone looked up the trouble code involved here, 36, which it turns out is a fuel related issue, not overheating. Does not appear overheating had anything to do with what happened here. Also, is kinda funny how folks with diesel generators swear that these Onan generators are water-cooled, since theirs is. Onan GAS powered RV generators have almost ALWAYS been air cooled, and still are. 🙂

[blawless]

Could be as simple as while driving down the road you let your fuel gauge go below 1/4 tank. The geneator fuel inlet will not suck gas below a 1/4 tank as a safety feature. If between 1/4 and 1/2 and you were going up hill or down hill on a long grade it will also be below the genny inlet tube in the gas tank and cause the same problem.

[Effy]

bluwtr49 wrote:

lakings10 wrote:
People there are no "radiators" on onan gens lol.

Look again, flat radiator at the bottom of the housing.

On an ONAN 5500 gas? Pretty sure that's air cooled.

[bluwtr49]

lakings10 wrote:
People there are no "radiators" on onan gens lol.

Look again, flat radiator at the bottom of the housing.

[lakings10]

People there are no "radiators" on onan gens lol.

[bluwtr49]

The most common causes for the overheat shutdown (besides low coolant) is a radiator clogged with dirt, a slipping fan belt, followed by a defective temp sensor.

[jbrad13]

Effy wrote:

mdanielson55 wrote:
It should handle the acs. Make sure when your running both acs that the elect water heaters and micro wave isn't used or coffee maker. thing to check is that the gens radiator is full on water an I run water wetter in mine as I do my cars. Doesn't hurt anything.

No idea what you mean by the gens radiator is full on water and you run it wetter than in your cars ?? This is an air cooled gen. And what is wetter water? :h

Heard a weather reporter on a local TV station in Texas say, "We are going to have rain today, but it will be a dry rain."

[Wrong_Lane]

Not sure of the exact model you have but here is a link to a service manual for Onan RV generators. Even if not your exact model the steps to trouble shoot your problem would be the same.

https://www.cumminsonan.com/www/pdf/manuals/983-0501D.pdf

(Not sure how to make a Clicky so you will have to copy and paste the address)

On my Onan 5500 Fault Code 36 normally indicates a fuel issue. Check the fuel lines for cracks or loose clamps. Change the Gennie fuel filter and check the genie fuel pump.

To me this sort of issue is one of the benefits of owning a motorhome. There is always something to adjust, repair or diagnose.

Good Luck and Safe Travels!

[Effy]

mdanielson55 wrote:
It should handle the acs. Make sure when your running both acs that the elect water heaters and micro wave isn't used or coffee maker. thing to check is that the gens radiator is full on water an I run water wetter in mine as I do my cars. Doesn't hurt anything.

No idea what you mean by the gens radiator is full on water and you run it wetter than in your cars ?? This is an air cooled gen. And what is wetter water? :h

[Effy]

This problem is more common than I first realized a few years ago. Take an air cooled gen, road surface temps near 100, contained in a bin with little airflow, running full bore to power 2 AC's and it simply overheats. On my first ACE it was even worse, the gen compartment was directly behind the engine taking on all that heat. MH manufacturers do not put a lot of gensets in bins with enough ventilation and far enough away from the chassis exhaust. I cured the problem on my old ACE by installing a vented bin door. Thor paid for it and I haven't had the issue since. In ideal conditions it's true they should run without issue, but when they can't get the airflow to cool down, they shut down.

[jerseyjim]

Generator should run for DAYS and only stop when 1-out of gas or 2-needs oil topped off.
At least that is my experience with my generator, a 5500 GENERAC. I would think ONAN would be the same.

My generator is OK with both a/c units,and microwave all running that the same time.However, during these times, (not on shore power) I put my water heater on propane. No reason, just feel better.

[bullydogs1]

Make sure your generator is getting enough air to vent...I've seen where that happens when it doesn't get enough air to vent..also check oil, as the slightest low oil could trigger it to run hotter and thus kick..also make sure your cover is on right and snapped shut correctly..incorrect venting there could trigger a heat sink and cause that to kick the sensor..even the sensor itself could be a bit faulty when on the cusp...but that's the last thing I would think..hopefully you are still under warranty..

[mdanielson55]

It should handle the acs. Make sure when your running both acs that the elect water heaters and micro wave isn't used or coffee maker. thing to check is that the gens radiator is full on water an I run water wetter in mine as I do my cars. Doesn't hurt anything.