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OT: need help with a Onan 7500 Diesel generator

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Old 08-25-2003, 06:40 PM
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Default OT: need help with a Onan 7500 Diesel generator

I have a Onan 7500 Diesel generator that will turn over just fine but will not fire, I have checked all the simple **** and still nothing, dad took it to a dealer to have it checked out and they quoted him almost 4k to fix If anyone has any knowledge of theese generators would you please PM me.
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Old 08-25-2003, 11:47 PM
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Check the fuel solenoid.
Check the individual resistance of each glow plug AND the total resistance of all four. Make sure the glow plug relay is working.

Take the glow plugs out and check the cranking compression.

If the glows are all in spec, the glow relay is activating, the fuel solenoid is operating, the fuel system has been primed, and there is adequate cranking compression, then it will either run or you have a problem in the injector pump or governor assembly.

I believe that motor uses a mechanical injector pump that you set the ijctor timing weith shims. Remove #1 injector and see how closely the spray timing corresponds to the injector timing mark on the crank pulley.

Hope these vague guidelines are helpful.
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Old 08-26-2003, 07:30 AM
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I dont have the quote sheet with me this morning and I cant remember off hand. I will check tonight and post more.
Do you guys know of any RV forums or any other internet source I could find some info?
Thnanks

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Old 08-26-2003, 07:43 PM
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ok the paper says, rotor magnets defective, shorted stator and cracked genarator fan, may need inverter

total parts 2698.93
total labor 826.50
local misc charge 237.97

does this sound right
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Old 08-26-2003, 11:25 PM
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check rv.net. There is alot of good info there.
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Old 08-27-2003, 09:42 PM
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Magnets don't just "become defective". They could indeed become loose or shift out of position, which may be what the tech is meaning to say.

A shorted stator and cracked fan also indicate an out-of-position magnet.

I have found some helpful guys on the BoatUS.com forum.
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