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Topic: Generator cranks but will not start (Read 1201 times) previous topic - next topic

Generator cranks but will not start

My 7.5 Onan will crank over but I doesn't have power going to the fuel pump or solenoid. I jumped from the switch to the fuel pump and it works. Held throttle by hand I fired up. Can't find the reason I don't have power to the controls.

Re: Generator cranks but will not start

Reply #1 –
Possible bad high temp, low O/P shutdown sensor? Blown fuse some where? Just a WAG don't know much about Onan

Re: Generator cranks but will not start

Reply #2 –
Is it gas or diesel?

Re: Generator cranks but will not start

Reply #3 –
Diesel

Re: Generator cranks but will not start

Reply #5 –
I seem to remember that there is a circuit breaker that If tripped will keep it from starting.

Re: Generator cranks but will not start

Reply #6 –
What does the exhaust look like while the engine is cranking?
    White smoke = unburned fuel
    Black smoke = partially burned fuel
    No smoke = no fuel.

Open the oil fill cap to see what comes out while cranking.
       
If diesel cranks without starting it is not getting fuel. Crack an injector fuel line to see if fuel is getting to the injector while cranking. Be careful that is high pressure fuel. If no fuel check everything from the injector pump back to the fuel tank.

Re: Generator cranks but will not start

Reply #7 –
Quote from: Silvbullet –
My 7.5 Onan will crank over but I doesn't have power going to the fuel pump or solenoid. I jumped from the switch to the fuel pump and it works. Held throttle by hand I fired up. Can't find the reason I don't have power to the controls.

What year is your 7.5 Onan generator? Assuming it is around early 1990, it has very similar issue as mine.
I was able to get the generator running by supplying the fuel pump with external 12V power and hold the solenoid. But there is no 12V power came from the control box.


I have to buy a new control board (Onan 300-2604) from flight systems for $200

Also, there are loose wires. I couldn't figure out which one is loose, so I hired an experienced Onan technician to fixed everything.

According to the technician,
    • Loose ground connection at A11 board
    • Loose connection @ K13+14

If you open the control box, you will see all wires are labeled with these numbers. You can try to to tighten all screws you can find and see if it can fix the issue.

Good luck!
 

Re: Generator cranks but will not start

Reply #8 –
I just bought the control board, I think I broke the start switch messing with it so I guess I will buy one of those.