generator problem

[Mike Nunn]

We were running thru some pretty heavey rain today traveling down I71 on the way to the New York Rally when our generator shut off.  We are able to start it back up, but it runs very rough and the voltage is up and down.  Will be headed towards Akron tomorrow and onto I-80.  If anyone has any suggestions or knows of a good service spot we would appreciate it.
Thanks, Mike Nunn  

[Edward Buker]

Mike,

It sounds like water has gotten into switches, or the electronics, or sensors, or the generator, or a combination of the above. I would suggest that you do not run it f the voltage is wandering beyond normal bounds of a couple of AC volts up or down. If you are driving the coach, let a full day of dry weather pass by, and then restart the genset and see if the drying of the mositure resolves your problem. If not then see a service center.

Later Ed

[Mike Nunn]

Thanks Ed.

[Mike Nunn]

We had the fuel filter changed and it was a little dirty but no sign of water. The mechanic that worked on it was a  truck repair guy and was not comfortable going any further. He thought it might be getting air from somewhere as it will start fine and runs fine except  it. Misses real bad for a second then runs fine again for a little bit and so on.
Where would I look for a air leak? Again we had no problem until we came through the heavy rain.

[Edward Buker]

I have seen an air leak right at the filter, that being a flair fitting. That site will usually form a drop or drip fuel if it is not tight enough. It is likely the mechanic tightened it enough but it may be worth checking. You could look for any fuel fitting that weeped fuel as part of the injection system but those leaks are rare. The fact that the rain was heavy may or may not have anything to do with the source of the problem. Rain would not cause an air leak into the fuel system for instance. Given this is diesel there are no ignition sources sensitive to moisture as there would be with a gas generator.

You are either having some electronic control of the generator causing it to briefly stumble and recover or you could have a legitimate air leak. You may also want to pull the air filter just to be sure it does not appear plugged. The fact that there was dirt in the filter may have some bearing on this problem and probably worth mentioning if you seek repair.

With the obvious things out of the way it may be time to have the problem diagnosed by a good Cummins service center.

Regards Ed

[Gerald Farris]

Mike,
Your problem sounds more like a control board problem than an air leak, however the only way to be sure is to have a qualified Onan (Cummins) technician check the generator.

Gerald

[Glenn Perkins]

If your travels bring you to Albuquerque, Rocky Mountain Cummins has (in my estimation) the VERY best generator technician I have ever found.  His name is Ken Vick and he has exclusively serviced our generator for the past 6 or so years.  If you generator smokes (black puffs) when it stumbles, you might want to check the air intake system too.  Our 10 K has managed to capture families of wood rats in the air intake a couple different times while dry camping over the summer on our wilderness property near the Grand Canyon.  Doesn't sound like it is your problem but still worth a check to ensure nothing is obstructing the air intake.