Onan electrical problem on a 1816

[wilman]

Hello, I have an 1816 Uniloader that has the Onan 2 cylinder engine in it like is in the 1816C. I am having problems with it dying on me after running for 3 or so minutes because the electric fuel pump suddenly quits. I turn the key off and than back on and the fuel pump will kick back in and the engine will start right back up, run for a while and die because the fuel pump has quit. If I take the fuse out that comes from the voltage regulator and runs up to the key, so that it is not charging the battery, the engine will run all day and the fuel pump will not quit. Put that fuse back in and after so many minutes, the fuel pump quits and the engine dies. Watching the amp guage, the guage will start jumping around right before the engine dies so I am thinking that it has something to do with the voltage regulator? Does this sound right? Any other ideas on what it may be? Thanks for your help Wil

 

[Tazza]

It is possible, but even with crazy voltage readings your battery should still supply enough power to run the pump. Does this machine run any sort of electronic controls? I'm thinking if your voltage is going wild, the computer may be telling the engine to shut down by turning the fuel off. It could even be a protection device?
It wouldn't hurt to put a tester on the battery to see what the charging system is up to, see if its over charging or not. If it is, you will only boil your battery.

 

[wilman]

It is possible, but even with crazy voltage readings your battery should still supply enough power to run the pump. Does this machine run any sort of electronic controls? I'm thinking if your voltage is going wild, the computer may be telling the engine to shut down by turning the fuel off. It could even be a protection device?
It wouldn't hurt to put a tester on the battery to see what the charging system is up to, see if its over charging or not. If it is, you will only boil your battery.

I checked the voltage going to the fuel pump. With the key on and the electric fuel pump going, it is at 13 volts. Start the motor and the voltage jumps up to 15 volts. The voltage will stay constant at that level even after the fuel pump quits working. If I take the fuse out that goes from the voltage regulator to the key switch so the battery will not charge, the voltage at the fuel pump stays at a constant 13 volts with the engine running. Voltage across the battery terminals with the engine off is 12.5 volts. Start the engine up with the fuse in so the battery will charge and the volts jump to 15 volts. So based on this I am thinking it isn't the voltage regulator but the fuel pump is getting weak and can not handle the extra volts going through the system when the voltage regulator is charging the battery. The fuel pump does feel a little warm when I touch it after it kicks. I am thinking right on this? Or is the voltage regulator putting out to many volts? Thanks Wil

 

[Tazza]

I checked the voltage going to the fuel pump. With the key on and the electric fuel pump going, it is at 13 volts. Start the motor and the voltage jumps up to 15 volts. The voltage will stay constant at that level even after the fuel pump quits working. If I take the fuse out that goes from the voltage regulator to the key switch so the battery will not charge, the voltage at the fuel pump stays at a constant 13 volts with the engine running. Voltage across the battery terminals with the engine off is 12.5 volts. Start the engine up with the fuse in so the battery will charge and the volts jump to 15 volts. So based on this I am thinking it isn't the voltage regulator but the fuel pump is getting weak and can not handle the extra volts going through the system when the voltage regulator is charging the battery. The fuel pump does feel a little warm when I touch it after it kicks. I am thinking right on this? Or is the voltage regulator putting out to many volts? Thanks Wil

It depends on the pump i guess, some are electronic others are straight electric. The electronic ones have a wider voltage range they can run in, i have one thats like 8-20v. Its normal for them to get warm though, but if you can't touch it you have a problem. I think they are pretty cheap, it may be worth while swapping it out.
As for the voltage, thats about rite. 14.8v i believe is the correct charging voltage, so 15 is close enough depending on the meter you used to check it.