Onan 5000 won't start

It's back in and running. It was a broken rotor caused by a mouse nest, just as the tech predicted.

By the way, if you need some RV service in this area, I recommend these guys. Easy to work with and fair charges.

Expert Truck and RV Service llc
614 vintage Rd NW
Oronoco, MN 55960
507-367-2333

427435 wrote:
Well, I got it slide out far enough to take the coil off. Open circuit between the + terminal and the spark plug towers. I'll order one in the morning.

I had the same no spark issue with my Onan 6500 a few years ago, changed the coil and that fixed the problem.

It wasn't the coil. The new coil had the same resistance readings. The Onan coil has two high tension/voltage posts. To check the coil, you take a reading between the two high tension posts.

Also tried grounding the oil pressure switch as well as just disconnecting it.

I finally threw the towel in and went to a local place that services MH's including Onan gensets. Told him the symptoms, and he promptly asked if there were signs of a mouse having been in it. There were pieces of paper towel in the fins of the engine, and we had found a torn up paper towel roll in the MH. He said the problem was very likely to be the ignition trigger arm deep inside the unit.



He replaces several every year------------mice get in, build a nest, and the first time an attempt is made to start the engine, the piece above gets broken.

I ended up disconnecting the genset and taking it to him. I'll report back if that proves correct.

Well, I got it slide out far enough to take the coil off. Open circuit between the + terminal and the spark plug towers. I'll order one in the morning.

427435 wrote:
It's been on shore power for a while and it cranks very strongly. Battery voltage is at 13.5 when plugged in and 12.8 when not.

Just trying to cover all the simple things first.

While those numbers look good, what is the voltage WHILE the starter is running ?

If it is above 11 you should be good there.
If below 11 then the battery is suspect.

Also check the connection that provides power to the ignition board or module.

It's been on shore power for a while and it cranks very strongly. Battery voltage is at 13.5 when plugged in and 12.8 when not.

427435 wrote:
I got some spark right after I took my finger off the start button as the engine slowed to a stop.

Could be an electronic ignition board or module problem but this REALLY sounds like your battery voltage goes too low while the starter is cranking.

Sometimes the spark fails before the starter quits running as the battery gets weaker.

Well, I got a little time today to work on the genset. Got enough sheet metal off that I had access to the oil pressure switch. I pulled the lead off. Still no start. I rechecked spark and noted that I got some spark right after I took my finger off the start button as the engine slowed to a stop. Put the plug back in but still now start. Sprayed some ether into the intake but still no start. However, it would fire once or twice after I took my finger off the start button and as the engine cranking slowed to a stop.

I've take all the bolts and exhaust loose so that I can slide it out tomorrow. Then I will check the coil. Hope it's that and not some control board.

RLS7201 wrote:
Remove oil filter to see oil pressure sensor.

Richard

Thanks.

Remove oil filter to see oil pressure sensor.

Richard