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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 26530
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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My Onan Cummins generator seems locked up won't start so I

Customer Question

My Onan Cummins generator seems locked up won't start so I pulled the starter off and the starter spins fine when I hit the button what could the problem be
Submitted: 4 months ago.
Category: Small Engine
Expert:  Curtis B. replied 4 months ago.

Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!

Expert:  Curtis B. replied 4 months ago.

Will the engine turn if you use wrench on it? If not remove spark plug and see if piston may have fluid on top of the piston.? If it does, spin the engine with spark plug removed to clear the cylinder, re-install the spark plug and see if engine will start?

Customer: replied 4 months ago.
Not really use to working on stuff like this I work on dirt race cars lol where can I put a wrench on it and try at
Expert:  Curtis B. replied 4 months ago.

You have starter off? Just use the ring gear on the flywheel to turn the engine using screwdriver to turn flywheel.

Customer: replied 4 months ago.
Ok motor is not locked up just won't start with starter
Customer: replied 4 months ago.
Starter spins when I take it off but will not when I bolt it up
Expert:  Curtis B. replied 4 months ago.

So engine will turn 360 degrees, and starter works when removed? But will not spin engine if stater is installed and spark plug is removed? Do you ave a voltmeter to test battery voltage? Has to be 12,5 before start and not drop below 8 volts when starter is selected.

Customer: replied 4 months ago.
Ok starter on with spark plug out will still not spin but spins when off and flywheel on motor turns 360 degrees with screwdriver
Expert:  Curtis B. replied 4 months ago.

What is battery voltage when you engage starter? Less than 8 volts, battery or cable problem. over 8 volts, starter or cables! I'm thinking battery problem. Does not have enough amps to crank loaded engine.

Customer: replied 4 months ago.
Dumb question what do I set on meter to for a battery
Expert:  Curtis B. replied 4 months ago.

DC volts, which will be straight line diagram. Red lead on positive and black lead on negative battery terminal.

Customer: replied 4 months ago.
12.5 volts and 10 volts when I hit switch
Expert:  Curtis B. replied 4 months ago.

So battery test good. I think you need a new starter!

Customer: replied 4 months ago.
10-4 will get one Tommorow and try that and get back with you!
Expert:  Curtis B. replied 4 months ago.

OK>

Customer: replied 4 months ago.
Put new starter on still nothing so I tried spinning flywheel again both ways and it spins almost 360 degrees and locks up on the last little bit in both directions
Expert:  Curtis B. replied 4 months ago.

Did you try it with the spark plugs removed?

Customer: replied 4 months ago.
does same thing and everything looks fine spark plug looks new also
Expert:  Curtis B. replied 4 months ago.

But engine does not turn full circle? Has to be a reason engine is locked. I'm thinking you may have a valve stuck open.