Onan 4000 won't start...again

We must never ignore the GROUND! So much focus on Fuses, Switches, Terminals, forgetting the Other Half of the circuit.
Glad it's fixed. Shame "somebody" didn't get it tight.
I used to fix lots of GM/Delco starters. Plenty of them, many parts interchangeable, special tools not needed. I could usually get two or three good starters out of four or five failed ones. Buddy had a parts shop and I could get the easy parts from him. Bearings, Brushes, Solenoid, Drive. Then he opened a rebuild shop and I could get a Armature, or a Field, even a "Nose" to change application.
He offered me this simple test process:
If it won't run, bypass Solenoid.
If it runs then, replace Solenoid
If it doesn't, replace Brushes
If it runs then, see if the Drive kicks to engage position
If it doesn't, clean or replace Solenoid or Drive
With starter running on the floor, hold down with one foot...
Jam end of a 2x4 into the Drive Teeth
If Drive teeth smoke the 2x4 and keeps running, setup is good
If Drive stops and Starter runs, replace Drive
If Starter stops, repair Starter (Armature or Field)

Ammeter's nice, but this pretty much covers it.

Glad it was something simple even though a lot of work to find and fix.

Nice to see a happy ending to this story. Hope the generator lasts you a good long while.

Oops, sorry. I thought I had updated all my posts. I borrowed a motorcycle jack from a neighbor and supported the unit easily while I undid the bolts. The hardest part was pulling the A/C wires back to the unit from where they went to in 1/2 inch flexible conduit, but with the DW pushing and me pulling we pulled out the wires and left in a pull wire.

Once I got the cover off the only thing wrong was a totally loose positive connection on the starter. I cleaned up all the unit (it only has 80 hours on it) and put it back in by myself then with me pulling and the DW pushing and adding dish soap to the wires, we got it back together again and it ran fine.

I can definitely see the minimum price of $600 for a re and re job alone, it was a pain in the butt, but I am glad I did it myself.

Just remember the world will not work without battery and ground.

Juzaxadar wrote:
Dumb question, maybe. It's in the back so how do I hit it with a hammer? I'm trying to avoid taking it out if I don't need to considering the time investment everyone is saying is involved.

Assuming it's a typical sort of installation, you can't get at the starter without removing the generator, unfortunately. You need to remove the outer upper case from the base plate, and usually that means dropping the generator since you can't lift the cover off with it installed. (I say "usually" because if I said it was always the case someone would point out that the '93 Craftwood Magnificat motorhome, of which five were built, provided access to the generator from above by swinging the couch seat up out of the way or something similar.)

I went through this with mine several years back and it drove me crazy for a while. The lesson I learned is just because it sees 12 plus volts that doesn't mean the amps required are getting through. Also I could not turn it over with jumper cables either. After cleaning and tightening all the battery connections I traced the line going from the genset to the battery I noticed the wire inside the crimped copper terminal was green and slightly loose after I clean the wire I soldered the terminal onto the wire and all was well again. I would check carefully your battery connections first and make sure they are clean and tight then wiggle your wires. It might be something simple especially on a newer MH like yours. Good luck.

Dumb question, maybe. It's in the back so how do I hit it with a hammer? I'm trying to avoid taking it out if I don't need to considering the time investment everyone is saying is involved.

Like others have said--Give it a good rap with a hammer on the starter motor itself, probably a stuck brush inside. Report back with results.

Is this the sound it's making? I'm trying to debug mine as well. Mine's a 4KY FA that was running perfectly last month when I started it.
https://www.youtube.com/watch?v=AiA-io1aWf4