Onan fuel pump is noisy

[Rick_Hixon]

Just bought a 1999 36 ft Holiday Rambler with 18,000 miles. The generator stop working the 1st day I brought it home. The Onan 5000 was not getting any gas. The coach tank was at 40% and I am not sure if it shuts down with that much fuel left? Seems like it should shut down closer to 1/4 of a tank? I did get the generator going after filling the tank. I by passed the starter with a hot wire and let the pump run for a long time. I held my finger over the gas line and the pump made an awful knocking sound. The generator now starts right up and runs under all loads but the fuel pump is still very loud even after 30 minutes of running. I am just wondering if I should change the pump or this is normal.

RickH

[Rick_Hixon]

Thanks everyone for the advise. Just looked on Amazon and found the pump and cant beat the price. Mounting in a different location is fine by me. It has to be quieter than the one I have and will be easier to get to in the future.

[othertonka]

Rick, are you aware that you can prime (run the fuel pump) by just pressing and holding the STOP/PRIME button on the genset and listen for the pump to click? I do this if the genset has not been run for awhile. As for the fuel line it should run at least down to a 1/4 tank, Could be your fuel gauge is off.

[Harvard]

The pressure from these pumps come from a spring loaded piston/solenoid that is cocked by a 12 Volt pulse a number of times per second. A normal noise response can be louder on first couple of pulses but should quiet down as the piston has little or no movement by virtue of the fuel flow being blocked by the carb float.

If a pump is noisy it may be because the fuel is leaking by the piston rings and not building a fuel pressure so the piston continues to move a full stroke on every 12V pulse.

[WyoTraveler]

I had to have my fuel pump changed out on warranty. Onan has had some problems with fuel pumps because of the heat. Mine was throwing code no fuel.

I talked to the Onan repairman and he said it is the heat. Amazon sells a fuel pump but not the exact model. (won't install in same place) However, if I have another problem with my fuel pump I am going to move the fuel pump away from the generator. Maybe mount it on the MH frame where it is cooler especially in very hot weather. I asked the repairman why Onan didn't move the fuel pump. His reply was that some installations require the Onan generator be set up as a complete unit so a separate mount for the fuel pump would just be inconvenient for Onan.

I have seen a couple of posts where RVers have purchased the Amazon fuel pump because it was cheaper and seemed to work out OK for them. Just has a slightly different mounting configuration.