generator shutting down

[mark carneal]

I  have a 10k generator that, under a load and 90 plus degrees outside, shuts down after running for about 2 hours.  The 2nd level fault code it displays is 36.  Has anyone else had this problem and what have they done to fix it?  I have taken all of the corrective action stated in the manual,  serviced it regularly and exercise it monthly.  In cooler weather it runs great all day.
Thanks,
Mark

[Edward Buker]

Mark,

That code seems to indicate that the generator dropped below 1000rpm. Do you sense before the shut down tha there is some fault in the rpm stability or if this is is a false sensor reading being supplied to the controller? The normal RPM is 1800RPM so it should be relatively easy to judge if the unit actually went to 1000RPM for a second and then shut down or just shut down and gave you the fault code for low RPM. If it really lost RPM I would look for a fuel issue, filter, air leak, or fuel pump.  If the unit starts right back up easily and runs for awhile normally after the shutdown then it would seem less likely to be a fuel system issue especially if you do not sense the RPM droppaged to be occuring first. In that case I would look to the controller board or RPM sensor as the problem source.....mixed in is always a possible poor wire connection possibility.

I have not had this problem or code fail but hope these thoughts might help your trouble shooting.

Later Ed

[mark carneal]

Ed,
Thanks for your insight.  It does not appear to loose RPM's.  It just shuts down and won't restart for hours.  It's like it is overheating, but giving a code 36.  Code 36 does not reference overheating.  Fuel filter is new.  I am hesitant on taking it to Onan for service until I better understand the problem.
Mark

[Roy Warren Co-Admin]

Mark,
When I had that problem, I had to replace the controller (circuit board).  It had gotten wet at some point (condensation from my engine air0 dripped onto the generator and shorted the circuit board.  It would run for a little while then shut down and I couldn't start it again until I replaced the circuit board.  Onan had to diagnose this problem.

[Edward Buker]

When it won't restart, I assume that it cranks. If it cranks and will not start, that would have me back thinking maybe a fuel system problem.  I have had a situation in a boat where a fuel filter would load up with contaminants on the filter face essentually plugging it and killing the engine.  With time, the fuel pressure would bleed off that held the contaminants on the filter face, unplugging the filter face and the engine would start again and run for some time only to repeat the process again. I have no way of knowing if that is happening here, but it may be possible. Seems like you could crack the filter output side fuel line when it shuts down and see if fuel is present while cranking, given it as a relativley simple check.

The fuel cut on/cut off is probably a 12v feed to a solenoid valve, or an electric fuel pump.  If that 12v feed is accessable to get a measurement, you could check the voltage while first cranking and running normally. Then see what it is when it quits. Then see what it is when it cranks and will not start (assuming it cranks). If while cranking and not starting, the voltage is more like it was when it was cranking and running, then I would think the fuel system is at fault and must not be delivering fuel. (air in line, plugged filter, etc)  If the voltage was more like it was when shut down, then I would think that the control board is not enabling the fuel pump or solenoid valve electronically, due to a sensor or control board issue.

Later Ed

[Edward Buker]

Mark,

I know that the code is not over temp but you seemed suspicious. These are some IR gun profiles for an overheat vs normal operation situation that I went through before I changed my belt. From an earlier post....

Possibly a slipping belt could be the culprit causing an over heating shut down. On my Onan 10kw you will not hear the belt slip so ther is no sign, just a shutdown. If you have or can get hold of an IR gun and aim it at the radiator face and the oil pan after the unit cuts out or after it has run under load for 1/2 hour. The oil pan should be about 150 degrees and the radiator face about 120 degrees if the belt is doing its job. If you see 200 degrees or more then the cooling is inadequate and the most likely cause is the belt. At least you can rule the cooling and belt issue out with some simple measurements.

The one main difference is that my generator would restart in a few minutes but would not run as long given the engine was already heat saturated. Your two hour wait to start seems like some other issue.

Later Ed

[mark carneal]

Ed,
Thanks for all your insight. I'm going to try your recommendations and I'll let you know.
Again, Thanks.
Mark