Genset Shutting Down In Heat

hikerjohn7 · 07-31-2016, 03:11 PM

We traveled from Florida to Tennessee this month and the weather was so hot we had to run the Genset (Onan) late in the day so the cabin AC could keep our passengers cool.

We had a problem with the Genset in that it kept shutting down at odd times. For instance, if it was running at a rest stop, as soon as we got back out on the highway, it would cut out and would not restart for a while.

Has anyone else had this happen with their Genset? I am wondering if it could be vapor lock since everything downstream of the Ford engine got really hot.

ilmor · 07-31-2016, 03:25 PM

I've read about others that had this problem, and it was apparently vapor lock. They added a vent to the generator thru the hatch so that cooler air is fed to it. I think Forest River even provided some to customers.

wahoonc · 07-31-2016, 03:44 PM

Possibly a vapor lock or overheat situation. I had this happen to ours this past weekend, we stopped for a short doggy break and to hit up an ATM. It shut off right before we were ready to roll again. It started back up a couple of miles later. One thing is to make sure you have plenty of oil and consider going to a heavier duty oil. I use 30 wt in mine during the hotter seasons and it seems to help. These things run HOT, I have brown grass spots at home where I had it cranked up to run for a bit and was off the gravel parking pad. When you have temps in the 90's and you are on blacktop, it is going to be brutal for the generator. They are air cooled, and with 140°+ air you are going to get limited cooling.

I too have heard about the added vents from FR but have yet to see a comparison picture.

Aaron

RVnut · 07-31-2016, 06:14 PM

I will add that we had this happen a few times with our Generac on our last MH and it was due to a thermo switch that protected the generator when it got to hot from the temp of road and air.. I replace the switch and problem stopped.. I dont know if Onan has this switch too

Kevin M. · 07-31-2016, 08:24 PM

Is the generator shutting off or just the AC's?

kenandterry · 08-01-2016, 08:22 AM

Kevin M......

The problem discussed here is with the generator shutting down.

I have the same problem with a Generac generator only when driving under hot conditions. When we're parked the genny runs fine. I suspect it's the increased heat coming up from the road pavement combined with the fuel sloshing around, possibly vapour lock of a simple carburetor design, or the low oil sensor tripping a shut down from the genny oil level sloshing around while driving.

NCCoachMan · 08-01-2016, 08:35 AM

Generator shutting off sounds like vapor lock.

Generator running but no power to coach sounds like transfer switch problem.

There are several conversations about these issues here. I wish we had some definitive answers.

hikerjohn7 · 08-01-2016, 09:31 AM

Quote:

Originally Posted by hikerjohn7

We traveled from Florida to Tennessee this month and the weather was so hot we had to run the Genset (Onan) late in the day so the cabin AC could keep our passengers cool.

We had a problem with the Genset in that it kept shutting down at odd times. For instance, if it was running at a rest stop, as soon as we got back out on the highway, it would cut out and would not restart for a while.

Has anyone else had this happen with their Genset? I am wondering if it could be vapor lock since everything downstream of the Ford engine got really hot.

Good feedbacks. Thanks.

I guess I will do some more research on the mentioned cut-off features in my Onan.

kenlea98 · 08-01-2016, 01:20 PM

I just had this problem with mine and it was the fuel pump. Would run fine for a period of time and then shutoff. Thought it was temp related but then read about vapor lock due to low fuel pressure. Replaced it and both filters and runs great now. May not be your problem but have seen numerous post here and other blogs that indicate it is a pretty common problem.

gizmo98 · 08-01-2016, 02:41 PM

I have 20 hours on my onan generator 4000 watt and a mechanic friend recommends replacing the oil with full synthetic swears by it and is great for changes in operating temperatures

ChrisAndGarren · 08-01-2016, 05:18 PM

We had this problem last year - took the coach to the Onan-Cummins dealer and they played with it for a week and couldn't replicate the problem. I had them do a full oil change (since we were there and all) and it's worked fine ever since. When I was doing my research, there was a lot of speculation about the fuel filter getting clogged as we were driving - but never got anything definitive.
Kinda frustrating, but it works now so okay......

Garren

ChrisAndGarren · 08-01-2016, 05:28 PM

Here's the link to our thread from last year.....maybe will give you some ideas?

http://www.forestriverforums.com/for...0-a-84357.html

Iwannacamp · 08-01-2016, 05:31 PM

X3 on the oil. Use an OEM spec synthetic oil. It will reduce the operating temperature and save fuel at the same time.

Sent from my iPhone using Forest River Forums

pdqparalegal1 · 08-01-2016, 05:34 PM

Had same problem. My diesel gen supplied by electric fuel pump so--NO vapor lock, that was a myth of the 50's. Took it to a Gen shop. Radiator had so much dust and dirt in the fins it couldn't cool in high heat. Cleaned the fins with engine de greaser, water, and air. Problem solved. May work for you, worth a try and cheap.

gmann32 · 08-02-2016, 08:10 AM

I had trouble for a year before I replaced the fuel pump! Was told to replace Cummings fuel pump with airtex pump! No more problems! This is on an Onan 5500 watt gas generator ! Good luck! Travel safely!

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