Onan 5500 fuel pump not priming

[Rsnawder]

Hello everyone...love to hear your feedback. I have a Georgie boy Landau 2005 with a 5500 onan generator. The generator was having problems starting so I took the RV to a repair shop and one test they ran was spraying carburetor or fuel cleaner into the front of the carb which allowed it to run for a few seconds. They diagnosed it as a bad carburetor. So $600 later they replace the carburetor and still the generator will not start. While trying to prime the generator you can hear it click but no fuel was coming out. So I left there they told me I need to go see an onan certified generator repair shop, at home this morning I just on a whim tried it and the fuel pump will prime...I can hear it and see the hose filling. So I shut it off to try it again and the same problem there’s a click and no priming. Anybody ever had this before? Thanks for your time!

[Rsnawder]

Filled to 3/4 tank, same results. I’m going to try 2 things:
1). Charge all batteries to fill then try again
2). Leave the gas cap off.

It’s a stretch...any other suggestions?

Thanks!

[Rsnawder]

Will do..then I’ll report back. Thank you

[dougrainer]

Rsnawder wrote:
Thanks Doug...so the prime seems to be intermittent. It was just running for about 5
Minutes then stops. After it stops all I hear when I go to prime is a click...no fuel
Moving. If I wait about 10 minutes it’ll prime and start again, run for about 5 min then shut off. My fuel tank is between 1/4 and 1/2.

Get the fuel tank above 1/2 tank and retest. Your 1/4 tank pick up may not be accurate. Doug

[Rsnawder]

Thanks Doug...so the prime seems to be intermittent. It was just running for about 5
Minutes then stops. After it stops all I hear when I go to prime is a click...no fuel
Moving. If I wait about 10 minutes it’ll prime and start again, run for about 5 min then shut off. My fuel tank is between 1/4 and 1/2.

[dougrainer]

The most common problem with a 10 year or older Motorhome, is, the rubber fuel line from the Fuel tank pick up tube to the Genset has dry rotted. The small cracks cause air thru the rubber and that disables the fuel pump from getting its prime to pull fuel. A quick way to determine this is to connect a gallon gas can and remove the existing fuel line from the genset and connecting a good new rubber line and see if the Fuel pump then primes. Usually it will. Doug

PS, If you hear a click, that may be the fuel cut off solenoid opening. BUT, you should also hear the Fuel Pump rattling trying to pump. This would mean your above fuel line is good. Also, I believe the fuel pump has a pressure cut off. When the fuel pump cannot pump, its internal pressure switch shuts off. When testing the fuel prime you need to disconnect the metal line at the Carb input. Onan and other Genset makers require a LOW pressure fuel pump which is what Onan makes and supplies. The aftermarket Automotive similar looking pumps are 2 to 3 times the PSI of a genset pump.