Onan 4000 Runs only with Door shut

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djkelsoe

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Aug 21, 2006
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First, I am a newbie to this forum and enjoy reading all about issues.  I recently had one happen to me that you all might want to know.  I recently purchased a Toy Hauler with an on board Microquiet Onan 4000 generator.  The unit would run for about an hour then die and only start and run for 15 minutes at a time after that.  I took it in for service and it was diagnosed with a bad fuel pump which they replaced under warranty.  They said they ran it for over 8 hours to make sure verything worked fine.  I got it back and opened up the Toy Hauler door and ran it for about an hour and same thing happened, it stalled after about an hour.  I then took it to another dealer for minor warranty work along with the generator problem.  They also said the generator worked fine and nothing was wrong.  I then brought the unit back and kept the door closed on the Toy Hauler and everything worked fine.  It appears that the generator needs for the door to be closed for proper cooling.  With the Toy Hauler door open it appears to over heat.  Anybody else experience this???
 

Gary RV_Wizard

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Feb 2, 2005
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That's one I haven't heard of before! 

I assume the "toyhauler door" refers to the big rear (or side) door for laoding the toys. Where is the genset compartment? Can you identify where/how it draws air through the interior of the trailer?  Maybe there is an opening somewhere you could block, so that you can run with the door either open or closed.
 

djkelsoe

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Aug 21, 2006
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I meant the generator door, not the rear door for loading.  Sorry if I did not make this clear.  Apparently, it needs to draw the air in from a particluar area of the generator or it will overheat.
 

KodiakRV

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Aug 19, 2006
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djkelsoe said:
I meant the generator door, not the rear door for loading.? Sorry if I did not make this clear.? Apparently, it needs to draw the air in from a particluar area of the generator or it will overheat.

Yes, that's exactly what the head mechanic at the dealer told me last week when he gave me a run-through on my new MH.
 

Gottasmilealot

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Oct 8, 2006
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As previously mentioned, I believe the generator is overheating because the air is coming in through the door opening instead of the designed air route from the intake area as intended by the design.  It's probably shutting down because it's too hot.  At least you know the overheat protection is working, but having it run too hot is not a good thing.  Keeping the door closed also prevents a curious child from being burnt reaching in.  Keep the door closed, as it's most likely designed for that type of operation. (It will also help muffle the sound and have you be a god neighbor). Knowing this, the service techs probably had it running with the door shut, and didn't see a problem.  At least the solution was easy! Your owner's manual might relate to this. Additional information may also be available through the website of you unit's manufacturer. In your position, I'd email the manufacturer and see what they say about this for your particular model.
 
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