Onan 7000 Generator problems

[Sean Marconette]

Thanks Rich,
I hate throwing parts at things to resolve problems, but I have resorted to it on this problem.

I have questioned the generator battery and had it load tested tonight. It was deemed bad, it was the original 2006 marine battery for the generator. It has not been allowing very many starts and would need recharged. It may have affected the module operation, as a stabile 12 VDC to the generator is needed. I also replaced the Mr Gasket 42s fuel pump that has been on it for 2 years now just to remove it from the equation with the same exact pump.

I ran the unit until it reached normal operating temperature. I then shut it off and let it heat soak the module, and when it would generate code 37. I then manipulated the choke while spaying carb cleaner to keep it running. I monitored the 12 VDC to the carb solenoid and fuel pump, and could never get it to change, always 12.7 VDC while running even with the carb cleaner. This confirms what you suggested, that it is a fuel issue. I removed and cleaned the carb and float bowl. After reinstalling, it restarts and runs easier, but will still code 37 if the choke is wide open when starting while hot. If I manipulate the choke, I can get it to run. After running, I can then allow the choke to go wide open and no issues.

As for the solenoid circuit or pin, I may add an additional gasket/washer to increase the clearance. As I wonder if the expansion from the heat is reducing the fuel volume.

As for the fuel pump/solenoid circuit. Keeping this safery circuit automated would not be that big of a deal. By adding a 120 VAC relay, and the coil energized by the generator when running would close a NO contact. The contact would have the battery 12 VDC + to the line side and the fuel pump/solenoid coil to the load side. The priming circuit would be in parallel. The same operation that is currently used by priming the unit before starting. Once the generator starts and produces 120 VAC the relay would then close and turn on the fuel pump/solenoid coil. When the generator is stopped the 120 VAC relay will be deenergized and the fuel pump/solenoid coil will be disabled.

I will try some of these ideas before reinstalling the genset back in the trailer.

I appreciate your time and help with resolving this issue.

Thank you
Sean

[Rich Biebel]

You could come work with me.....LOL

I once fixed an older Onan that had a 24 Volt AC circuit failure in the stator by using the 120 VAC output fed to a small transformer and applied to the control board. Mounted the transformer outside the endbell.....added the wiring and it worked perfect.

The 24 volt ac was used to operate circuits on the control board and keep the machine running. A new stator was not available. Older flathead 1800 rpm machine.

I get creative sometimes if needed and if it makes sense.

Keep in mind if you never lose that 12 volts to the carb solenoid and fuel pump......your issue is NOT the PC board....

These machines are very hard to restart hot and I have not come up with a fix for that. As you see, if you close the choke as you crank it hot.....it will start right up usually. Otherwise they may crank a very long time and or not start without numerous tries or waiting a while.

The engines are Subaru-Robin built I believe. Not sure on that or who may have designed them but they really need to address some serious issues on them.

I am installing a new engine right now on one. 7KW.....6600 hours

[Rich Biebel]

Here is a little tip that I thought of today....

Has only happened a couple times but...

The mufflers on some Onan's can get plugged up with carbon and soot...

Back pressure goes up and the engine does not run well once it runs for a while....

I disconnected the muffler from the exhaust pipe from the engine and engine runs fine.

This occured during a load bank test and would not be readily apparent without testing it this way....

Another piece of info I am just throwing out there ....

[Sean Marconette]

Heck we might make quite the team! I would not know what to do with racing in the atmospheric conditions you have!

It is somewhat concerning that this thing gets as hot as it does. I will take a look at the muffler, good thought. I can't say I am a big fan of this air cooled design.

Thanks Rich!

Sean