Onan not starting

[pbsurf]

Onan 8MDKAL EHL 729
About 9 hours of Onan run time earlier I completed ( I hoped) a part switch out because it acted like it was the culprit, the stop solenoid. It looks like it attaches to the speed control level. When it runs the the stop solenoid pulls the lever back. A few starts back, the change was again noticed the start turnovers had slowed down, like the battery was too low. 12.7V was measured. Spent $50 China product on Amazon, found a made in the USA in Kansas for $187 but had a week plus wait time. $250 for marine suppliers here but not in stock. Before the stop solenoid working it's magic it seemed to jerk back and forth. Contacted a generator mechanic this morning..
What is killing the stop solenoid? The starter? Bench test it?

 

[pbsurf]

Ideas from Hard Starting Onan thread : 1) will be checking range of stop Solenoid and 2)condition of glow plugs.

 

[pbsurf]

this may be the easiest fix ever, I finally saw the positive wire lead to stop solenoid had backed 1/2 off. Runs

 

[pbsurf]

In slip, with the charger on, the batteries will rest with 13.6V. The Onan will start within a few seconds of cranking. With charger off, batteries 12.7, the Onan cranking slows, the voltage at the magnetic switch connection goes from 12.7 to 6.5 within 2-3 seconds and at the same time the stop solenoid cycles on/off rapidly.
Since I have the replacement magnetic switch onboard, I started to switch out that part. Now the last part of disconnecting is eluding me. The magnetic switch does seem truly magnetized. Now I'm worried I will break it if I try to separate it. It will pull away till the fastening studs are almost clear of the starter bracket, it doesn't want to go anymore.

 

[bluebyu]

Sounds like a bad battery.
During cranking I would expect no lower than 9 volts

 

[pbsurf]

Have had the battery charger off for 24 hrs. The voltage is 12.68 and the specific gravity in all cells is looking good around 1300. So, likely the problem isn't the battery. The magnetic switch plunger has a flat area that has me thinking that it is where it connects to a yoke inside the starter case. I have no idea how to release it and if I were able to have more doubt about reconnecting the replacement. Guessing starter motor has to be disassembled. Ugh

 

[pbsurf]

Blubyu nailed it! Load test on battery read Bad! Having that answered is a relief!

 

[Bmarler]

If you have that much voltage drop during cranking you should check at both ends of the battery cable, same for the negative cable. If you check there it can reveal poor cable ends or poor connections. Check volts in all those places while cranking.
It’s also possible the starter is dragging and simply taking too many amps. If you have a clamp on amp meter you could check that.

Oops, didn’t see the load test post….