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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15198
Experience:  Certified on Onan and Generac generators
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Generator starts, runs approx. 15 minutes, shuts down. Wait

Customer Question

Generator starts, runs approx. 15 minutes, shuts down. Wait 10 min. start up and runs approx. 5 minutes, shuts down. Why?
Submitted: 7 years ago.
Category: Small Engine
Expert:  Hank F. replied 7 years ago.


What is the full model number of your genset?

Customer: replied 7 years ago.
I believe it is a 6400. I am not home at this time to check for sure. Do you have a phone # XXXXX be reached and I will go home and stand by?
Expert:  Hank F. replied 7 years ago.

Sorry, but we are not allowed to share personal info like telephone numbers or email addresses.


The 2 most likely scenarios for this type of symptom are:


1. The vent in the gas cap has become plugged up with dust/dirt. To test, simply loosen the gas cap 2 or 3 turns. If this makes the set run, you will need to clear the vent or replace the cap.


2. Ignition system breaking down. To test for this, start the set and let it urn until it stops. Immediately check for spark while trying to restart it. If no spark is present, we will need to diagnose the ignition system.


Let mw know what you find out.

Hank F. and other Small Engine Specialists are ready to help you
Customer: replied 7 years ago.
Have already checked gas cap and vent on fuel tank. This generator is in a Toy Hauler travel trailer. Have loosened the gas cap. Still problems.
Expert:  Hank F. replied 7 years ago.

You had mentioned the fuel shut off valve, but not the vent in the cap. Sorry. I am just trying to cover all bases.


Since you have checked all that, the most likely case is a failing ignition system. Check for spark immediately after the set shuts down.


These are simple ignition systems, so it should not be difficult to diagnose. But I will need the model number from the data plate to know which system it has.

Customer: replied 7 years ago.
Model #5.5HGJAB-901-C
At the time I looked for the model # XXXXX the generator ran for 14 minutes before it shut down. Please help.

Expert:  Hank F. replied 7 years ago.

This set does not have a fuel tank (it uses the RV's tank) - where were you checking the vent?


This set is also microprocessor controlled. We need to see what Fault Code is being set.


Go to the genset and use the switch on the set itself.
Press 'Stop' 3 times within 5 seconds. The light in the switch will start flashing.
If the light flashes 3 times, pauses for 3 seconds, and flashes 3 more times, press and immediately release 'Stop' one more time.

This will put the controller into Fault Read Mode.

The light will flash (X) number of times, pause for 1 second, and flash for (X) number of times again. Count the flashes before and after the pause.

This will be the Fault Code.

Example: flash flash, 1 second pause, flash flash flash flash flash is a Fault Code 25.

There may be more than one Fault Code stored, so watch the light very carefully. If there is more than one code, it will display them all in order, and then start over again.

What Fault Code are you getting?

Customer: replied 7 years ago.
Thank you for this info. I will go home to my generator and try the data that you gave me and get back to you. It will take ma some time so please keep this in record for my response.
Expert:  Hank F. replied 7 years ago.
No problem. Just let me know what you find out.
Customer: replied 7 years ago.
Hi Hank! We are back. It flashes 3 times, pause and flashed 5 times. We tried it several times so this should be right.
Expert:  Hank F. replied 7 years ago.

Thanks for the info.


Unfortunately, I want you to re-do the test.


Code 35 is Control Card Failure. It means the controller is bad and must be replaced.


Let's make DARN sure it is Code 35. The controller is not cheap.


It is easy to replace, and can be done in about 15 minutes.


I have checked with my aftermarket supplier, but this board must be ordered through Onan. Go to and enter your ZIP or city and state to find the nearest Cummins distributor to you. It will run you between $300 and $350. Sorry.

Edited by Hank F. on 10/31/2009 at 9:38 PM EST