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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14726
Experience:  Certified on Onan and Generac generators
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My onan runs short time (30) minutes or less then RPM's

Customer Question

My onan runs for a short time (30) minutes or less then RPM's fluctuate and dies. In cool weather I texted and it ran for 3 hours and I shut off. Hotter weather shorter run time.
Submitted: 1 year ago.
Category: Small Engine
Customer: replied 1 year ago.
I would pay increased price if problem is resolved without taking to repair shop.
Customer: replied 1 year ago.
Please refund my $5.00. I have heard no answer.
Customer: replied 1 year ago.
I thought 10 minutes???? Not 2 days???
Expert:  Hank F. replied 1 year ago.

Hello, my name is ***** ***** I am going to assist you with this.

What fault code are you getting on the genset?

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: 2 rapid flashes, 1 second pause, 5 rapid flashes 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.

Be very careful not to misread a first level fault code (single digit code) as a second level fault code (double digit code).

The way to tell the difference is by the length of the pauses.

There is a 1 second pause between digits of a second level code, and a 3 second pause between codes.

For example, if it is flashing 2 times, 1 second pause, flashing 2 times, 3 second pause and repeating, then this is a second level fault code of 22.

If it is flashing 2 times, 3 second pause, flashing 2 times, 3 second pause and repeating, then this is a first level fault code of 2.

What Fault Code are you getting?


Customer: replied 1 year ago.
Expert:  Hank F. replied 1 year ago.

This is a prime example of a fuel pump going bad.

Start the genset, and let it run until it shuts down.

When it shuts down, immediately remove the fuel line from the carburetor. It will be necessary to cut the crimp-type hose clamp.

Place the fuel line in and empty container.

Press and hold the 'STOP/PRIME' button for about 10 seconds.

When you first press the button, there will be a 3 second delay before the fuel pump activates.

When the fuel pump does activate, it should make a faint 'humming' sound. It should not make a loud 'clacking' sound. A loud 'clacking' sound indicates that there is air in the pump, and can indicate either a faulty pump, or no/not enough fuel getting to the pump.

There should be an immediate strong, steady flow of fuel in a pulsing flow.

If there is no fuel flow, or if the flow seems very weak and thready, locate the fuel supply line.

The fuel line attaches to the fuel filter, and the fuel filter is screwed directly into the pump, which is located underneath the front left corner of the genset.

Remove the supply line from the filter, and attach a length of fuel hose to the filter.

Place the end of the hose into a gas can.

Now press and hold the 'STOP/PRIME' button again, for about 10 seconds.

If you still do not get sufficient fuel flow, the pump is bad and needs to be replaced.

If you now get good fuel flow, but did not on the first test, either your coach is low on gas (there must be at least 1/4 tank for the set to run), or the fuel lines between the tank and genset are bad.


Expert:  Hank F. replied 1 year ago.

Was this what you wanted to know?