Genset

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canusa

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Jun 2, 2005
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4
My generator runs for twenty minutes to a half hour, then shuts down. Leave it for a while, and it starts up and a half hour later, it shuts off, and so on. It's been mid 90's here temp wise, but if heat is the problem, what do folks in the desert do? The generator was serviced last week, and they discovered the problem and can't correct it. It's made by Onan, out of a 91 Winnebago, but the generator only has 146 hours on it. Any ideas? I'm stumped.
 

Steve CDN

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Jan 31, 2005
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Is your genset gasoline, propane or diesel?  Can you provide the model number?

When it was serviced, and a problem was found, what was the problem found to be and why could it not be fixed?

Did you take it to an Onan repair center?

In what way is heat turning off your genset...is there a heat sensor that shuts it off because it detects overheating or because the ambient temperature is causeing a malfunction?

Your input on these questions will help figure out a solution.
 

Gary RV_Wizard

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At our Silver Springs FL home
Many generators have an oil pressure sensor that will shut down the engine iof oil pressure drops too low.  This problem can occur due to foaming, even when there is adequate oil in the crankcase.  I'm not sure how to correct foaming, but I would start with an oil change using  a different brand of oil, perhaps even a synthetic.  Could be an overly sensitive pressure switch, though.

Vapor lock is another possibility and it is heat-related.  Insulating the fuel line where ir runs close to the [hot] engine may help.  Vapor lock can happen on propane and gas gensets, but is rare on diesels.

As Steve requested, let us know make, model and fuel type of your genset.
 

Woody

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Mar 10, 2005
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917
We just got back from a weekend drycamping trip where we ran the Onan generator in our 93 Pace Arrow continuously from 7AM Friday morning to 8Pm last night without any problems whatsoever. The temps were in the high 80's and low 90's all weekend and we needed the AC.

Woody
 

Karl

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Elkhart Lake, WI for the summer. Work at Road Amer
Foaming can be caused by excessive oil in the crankcase. When cold, check the level and make sure it's not above the "full" line. As Gary said, now would be a good time to change the oil and filter. Also check your genset fuel filter and if it's a gasoline unit, make sure you have at least 1/8th tank full. They shut off when the main fuel level is too low, but you may have a touchy level sensor that thinks it's low even when it isn't.
 

John From Detroit

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Apr 12, 2005
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Davison Michigan
I am coming up on 50 hours on my Onan, (it's running as I type) So far I have had one unscheduled shutdown, and it's entierly possible I caused it by hitting the wrong switch on the dash (The GENERATOR OFF switch) so I'm not complaining, though I do admit when I re-started it it quickly stalled, restarted again No problem

The other problem is last night (it's parked in the impound yard where I work... Just in case I need a toilet, we have none here, OSHA violation, you bet, but that's the way the boss has it set up, we got to call the guard, if he is in, next door, and use THEIR head) Well last night I got a CO alarm, Shut it down, opened up, cleared, Alarm repeated 3 more times... I did find a non-generator issue that may have been allowing exhaust fumes to enter the MH, fixed it (I hope) and as of 8pm... it was still working well (had been on since about 5:30) with no evidence of CO built up in the MH... Course I left an intake fan pulling in fresh air from a long way from the genset too, LOTS of fresh air, which means the AC units are overtaxed.. Well you get the mess up

50 hours is when Onan says "Change Oil" so.. It gets checked,,, Tomorrow
 

Gary RV_Wizard

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Karl makes a good point about low fuel level and the shut-off point is about 1/4 tank on many motorhomes.  No sensor is involved - they simply put the generator fuel intake a fixed distance above the bottom of the fuel tank so that the genset runs out of fuel before the tank is totally empty.  This applies to gas and diesel powered gensets fueled from the vehicle fuel tank.  Liquid propanefueled gensets probably do not have this sort of arrangements and I've never heard of it in gaseous propane versions.
 

Ned

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It's certainly foolproof, and no moving parts :)  However, if you ever do run the fuel down that far, you better have a self-priming engine on the generator.  I think we did that once on our Onan but it started fine when we filled up the fuel tank.
 

BernieD

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Mar 1, 2005
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Goodyear, AZ
Karl said:
Gee Gary, so that's how it works! Lots easier and cheaper to just suck air than put in a sensor. What'll those engineers think of next ;D

If those are the same engineers that designed the sensors in the holding tanks, I like the pickup tube better. By the way even Volkswagen used that methodology. Our 1960 bug had no fuel gauge. It had a pickup tube and went you ran out of gas, you flipped a lever to change to the lower pickup tube and you had your low fuel warning  :D :D
 

Charles

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Jun 5, 2005
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Florida
If the problem is caused by foaming, oil designed for diesels reduces foaming.  Be sure you're not using standard oil in a diesel generator or any diesel engine.
 
Joined
Jul 25, 2005
Posts
11
Charles said:
If the problem is caused by foaming, oil designed for diesels reduces foaming.  Be sure you're not using standard oil in a diesel generator or any diesel engine.

To add the what Charles said, there are anti foaming additives that can be added to the oil.  The additive can usually be found at an International dealership due to the type injectors used in the IH engines.  Silicone (RTV) will cause oil to foam also.
 
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