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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14436
Experience:  Certified on Onan and Generac generators
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Hank I'm having problems with my Onan microquite 4000 gen

Customer Question

Hello, Hank
I'm having problems with my Onan microquite 4000 gen
Mdl # 4kyfa26100k
I can get the geny to start it will run about five minutes then sputters and stops. I then disconnect the fuel line at the carb and crank the motor and no gas flow. Will wait a while and pump will work again. Don't know if its a heat related issue or what
Submitted: 2 months ago.
Category: Small Engine
Expert:  Hank F. replied 2 months ago.

Hello, thanks for requesting me!

What you are describing is either a bad fuel pump, or a bad fuel line.

We can easily test the pump.
To do the test, 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 supply line is attached to the left side of the set, about midway between front and back.
If you look down the left side of the set, you will see a large black ground cable, then a gray conduit (this conduit is the AC output wires), and then the fuel line.
The fuel line attaches to the fuel filter, and the fuel filter is screwed directly into the pump, which is located inside the set, all the way to the left.
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 2 months ago.

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