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Old 04-22-2014, 03:59 PM   #1
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Join Date: Nov 2012
Location: Oregon City, OR
Posts: 36
Onan Generator Won't Run

I have an Onan generator that was once in an RV and is operating on Propane. Model 6.5 NH-3CR/16000A. The issue is it won't keep running. When the start button is pushed, it cranks over and fires a couple of times, then fuse F2 (IGN) blows and when the start button is released it stops cranking. I am using Onan Control drawing 611-1135 dated 4-8-77. At first it was thought the seal-in relays K2 and K3 were sticking in the open position, but both have been replaced. Then looked at the Diode CR1. When I checked CR1 with the diode test fxn on my multi meter, it appeared to be open both ways. I replaced CR1 with a new diode although it also checked open both ways (no tone). Can you enlighten me on how to check a diode like this one, it is obviously different than the standard .7 volt diode. Regardless, I'm quickly running out of thoughts, looking at the schematic on the drawing, I see there is a C1 that might be shorted or could the points S2 be causing the fuse F2 to blow? Something is shorting out causing an over current through F2 and I can't find it. The start Solenoid K1 must be working as the generator is cranking over as long as the start button is held in. Again, it only fires a couple of times, then that must be when F2 blows and it quits firing (makes sense because no more current to the points and plugs). The only other thing I see in the circuit is S3 the low oil pressure switch, but the oil level checks fine.

Can somebody shed some light on why this fuse is blowing?

Thanks, Steve

Steve & Jane & Smokey the ferrel Cat
2001 F250 SD, 7.3 Diesel, CC, SB
2013 Wildcat Maxx 313RE Touring Ed.
Days camped 2013 = 51 (as of 26 Apr)
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Old 04-24-2014, 06:38 AM   #2
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Join Date: May 2012
Posts: 21
On the gas version that is usually a fuel pump failure or the control board that causes the fuse to blow as soon as you release the start button.

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Old 04-24-2014, 06:05 PM   #3
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