generator

Near 100 degrees today, running my generator along with air conditioning for 3 or 4 hours. Generator sputtered several times and died twice but started right up. Shut off generator for 20 minutes, would not start up again. After a half hour it started and ran fine. Oil level reads full, it acts like it was over heated. Needle on volt meter does not stay constant. The motorhome is 6 weeks old. What's up?

  Lynn

Similar problem last year in hi heat on my new 2910 and same results. Lower the level of gas in the tank worse the problem seemed as the generator stopped altogether at 1/2 tank of gas. It should have ran down close to a 1/4 tank before quitting. I may be wrong but suspect a vapor lock problem as it only manifests in 90 plus temps and close to mid tank levels. So far. So, when almost to my destination the tank is topped off and seems to help. I've not really put any effort into solving the problem because when I'm boondocking I'm dragging along a race car trailer with it's own generator plus an unmounted spare which is quieter anyway and runs the ac just fine if needed plus everything else and eliminates the vibration from the onboard unit. I got in this habit several years back when out 3 or 4 days so I wouldn't have to use the on board unit until the last day or so.

George

Near 100 degrees today, running my generator along with air conditioning for 3 or 4 hours. Generator sputtered several times and died twice but started right up. Shut off generator for 20 minutes, would not start up again. After a half hour it started and ran fine. Oil level reads full, it acts like it was over heated. Needle on volt meter does not stay constant. The motorhome is 6 weeks old. What's up?

  Lynn

The obvious...does your fuel tank have sufficient fuel? 

RVRUNNER,
Can you tell us which model of generator is installed in your PC?

Hi Lynn,

Being that your generator is brand new and it has adequate oil, this rules out all the typical troubleshooting suggestions about dirty oil, clogged oil filter, dirty air filter, and such.

First, make sure your Onan cover is mounted on properly and latched.  If the cover is not seated right, the air is not circulating properly, therefore is not cooling properly.

Second, make sure your altitude adjuster is set to the right altitude.  If not set right, your generator will be running either too lean or too rich which could make it run too hot.

George might be onto something.  Try loosening the motor home's gas cap to relieve any negative pressure in the main fuel tank.  If it works, your Ford chassis might require warranty work on the fuel evaporative system.

I did a quick Google search on "Onan Generator Overheating" and piles of hits popped up.  If the gas cap idea yields no results, I wonder if excessive heat is getting trapped up inside the generator compartment.  I would try this $50 experiment to see if it solves your problem.

Walmart sells THIS compact high velocity fan that you can aim with accuracy.  Place it under the RV and aim it so the blast of cool air is directed into the "Air Inlet"  louvers of the Onan.  Being in the right place under the motor home, the fan should be well protected from stormy weather.

If that yields no results, try doing the same blasting air in through the PC access door, if only to determine that the generator is actually overheating.  Maybe there is an issue with a heat sensor on the generator that your Onan warranty can resolve.

But maybe it is simply so hot outside that the solution is a high velocity fan to assist in cooling under such extreme conditions.  Hopefully others will reply sharing their own 100+ degree experiences.

I had this happen last year but it was about 110. It started to run erratic and died and would not start again.  Mech told me it’s about the heat ,ventilation and they vapor lock. I couldn’t even get it to start using ether. So I took off the side cover and left it open for ventilation. After about 30 mins I was able to get it started and it ran fine but I left the cover open for ventilation as it got to 115 that day.  No idea if this is the same in your cas but worth a try.

In the future if I’m traveling in high heat I’m carrying a small desk fan. I’ll leave it underneath, just to give it some circulation.

Sorry, I neglected to mention I also opened the access door to the generator (but not the side panel of the gen) to get some air movement and that seemed to help. That's one thing that made me think it's a vapor lock problem. I meant to trace out the fuel feed to the generator to see what color it is and if it might be possible to insulate from reflected heat from the ground if not already so.

George

I was running with full tank of gas, seems to me me the generator should run under any conditions. When I first got the rig the gen would start right up, now after putting some hours on you have to crank it a lot more before it starts. That leads me to think it;s not getting gas. I think I'll have an Onan dealer look at it. I really need the gen to work in high temps.

  Lynn

We had this problem with a previous RV.  I'm in Florida and it is often really hot.  My husband found that the gas line from the gas tank to the generator was rubber tubing.  When it got really hot outside, the tubing would soften and the gas couldn't get through.  He changed the tubing to copper, plus insulated any place where the tubing might be near an exhaust system.  Never had another problem.  This was from a 2006 RV, so hopefully the newer ones no longer use rubber tubing, but it might be something to check.

Peg

The Onan generator manual lists the following possible hot weather issues:
(1) Airflow is restricted (unit needs cleaning).
(2) Oil viscosity is incorrect.
(3) High altitude adjustment set incorrectly.
(4) Unit requires general maintenance (air filter, fuel filter, oil change,...)

I'm with Mr. Dittmer's suggestion of using a fan to help cool the generator.   Best guess, as as was noted by others, is a vapor lock.
Good luck and please let us know if you determine the cause.

It's been running fine for the last 2 hours, 92 degrees. I opened the compartment door. I have no Onan manual, just a disc that I haven't played. I don't know what weight oil comes in the generator, in this heat I should probably use straight 30 weight.

  Lynn

The following is a screen shot from the Onan Microquiet 4000 Operation Manual:

Thanks to all for the good advice.

  Lynn