Onan Marquis 7000 Generator Starter Revs But No Action

Those gear drives have a roll pin in it and kind of hard to take out and put in. Turn your flywheel by hand and see how hard it is to turn if its to hard to turn the gear drive just slips its a trait of that starter I have the same gen. It has no prime.
Bgm and nhm service manual

Thanks for the helpful replies. Gas tank near full, and the switch doesn't toggle to prime from what I can tell. J-D's suggestion seems to be the case, as it is spinning wildly (by the sound of it) and nothing seems to engage. I think I've found the starter on the back side of the generator where it is too hard to take off without dropping or maybe swinging(?) the generator down so I'll try that in the morning and take the starter off to look at the gears. We seem to have found a rebuild assembly from the Onan dealer for $50.

Your starter probably looks something like this



And if so it has a cheap plastic drive on it. From your words, it sounds like you are hearing only the starter spinning up. Correct? NOT the sound of the whole generator being cranked but not starting. Correct?

If I'm right in my understanding you have a good starter with a bad drive. But, on some of these ONANs, if you can jog the flywheel a little, a blocked or stuck drive may release and operate again.

That pic is from Amazon. I'm not sure the pic represents your starter. Somebody here can help you get to a service manual and a parts list. That said, the starters for several ONAN models seem to run between $35 and $55 on Amazon. If your generator design and installation allow changing the starter with the genset still in the coach, I'd replace starter with new.

That's if I understand your symptoms.

brisath wrote:
Using the starter switch on the generator, the starter revs very high but no attempt to turnover or start.

Are you saying the starter runs but does not engage the engine?

Are you priming before trying to start?
The start switch is a rocker type. Press the bottom and hold in for 15-20 seconds, then try starting.
Be sure there is over 1/4 tank of gas in the RV or it will not start. It is a safety feature that will not let the genny drain all the gas.