ONAN Marquis Gold 7000 Gas

[voltdr]

I am at the Topeka double.
After running great all week in Denver, my generator won’t
stay running when I let off the start button. The light on the button just flashes
while it runs. No 120V is being produced. I believe that it must produce AC
to keep running. No codes are showing on the Start button, but I have a control module from Flight Systems, and I think they don’t send out as many trouble codes as the ONAN units. Before ordering another control module, is there anything else to check first? Brushes, continuity?
Thanks,
Dan

[Hacksaw]

Rich Biebel is the man on Onans. I can say that I had one that fried the voltage regulator and would only run if the start rocker switch was engagad. Twice. Once because it ran out of fuel and the motor was surging and the other time caused by very slow cranking from a low battery. Hope this helps.

[1matcoman]

Man, what a place (and time of year) for your gen set to crap out! Sure it's hot as XXX there right now.

Hate to bring bad news, but your main control board is probably toast. At least that was what had happened numerous times to me when I ran gas sets on my work trucks for 30+ years.

[Rich Biebel]

Check the brushes first. They wear and can damage the surfaces they make contact on. Slip rings is the name for them. If the brushes are bad and the slip rings need cleaning, a piece of emery or sand paper taped to a paint stir stick cut lengthwise to fit in there works best. Start machine and hold button down or put the machine into ERO mode if it has that option. Engine Run Only mode. Brushes can wear out in 700-1200 hours and occasionally much sooner.

[voltdr]

Hi Rich, when I pulled the control board out I checked the brushes. The brushes and slip rings are good. I just received my new board and after installing it the problem is the same. It will only stay running if I hold the start switch down. Tom from Flight Systems
Is going to call at 2P to help troubleshoot the problem.
Thanks for your help.
Dan

[voltdr]

I have checked continuity of all of the windings and everything looks good. How is the
engine connected to the generator section? The generator appears to set at a 90 degree angle to the engine. Is there a belt under the unit to connect them?
Dan

[Rich Biebel]

Yes there is a belt and if it or the rubber coupler broke, the generators rotor won’t be turning. Pull the brushes and look in there and start it. Rotor should be spinning. Testing would get more involved if it is spinning.

[voltdr]

Thanks Rich. I’ll do that tomorrow.
Dan

[Hacksaw]

Dan: Not two months ago my 7000 gave me some grief. Started and ran but noisy like it was going to throw a rod and there was a very slight burned rubber smell. Turned out to be the rubber coupler under the engine flywheel that drives the belt to the gen. armature as Rich already mentioned.

[voltdr]

I removed the brushes and the slip ring does not turn when the engine runs.
I’m not sure which is broken, the belt or the rubber drive mechanism. I didn’t smell any burning rubber in mine. I will probably replace both since you have to separate the base plate to get to both.
Thanks for all the helpful tips.
Dan