Originally Posted by kthacker
I have an onan 4000 in my 2012 Sunseeker 3170 and 15 minutes into a drive the fuel pump starts starving for fuel with a full tank??? You can hear the fuel pump making the loud ticking noise once it gets hot and the generator cuts off due to lack of fuel. Once the motor home is parked and everything cooled I can prime and recrank the generator with no problem and it will run for days if you want. I live in south Louisiana and the couple times I've had this issue it's been hot outside. Ive read on some Onan forums that I might need to install an additional fuel pump closer to the fuel tank because the gas in the lines are boiling and the onan pump is losing it's prime due to this. I have already pulled the fuel filter upstream of the onan pump and nothing is plugged up or anything. Thanks in advance.
Here's a new thought for you. The main fuel tank to engine supply uses a pump in the main fuel tank. Its set usually near the center of the tank upper surface. The pump hangs to the bottom and pumps to the engine. You have found the gen will not operate with the engine running and coach underway.
When the M/H is idle the gen works because the pump can pick up and maintain fuel pressure. The gen suction pipe extends 3/4 of tank depth.
Wondering if the fuel tank is not venting properly allowing the fuel used by engine and gen-set from creating a vacuum in the tank. Normally its under a very slight pressure and vents through a carbon cannister. Not sure where its located in this chassis. Auto and truck cannisters usually in under hood area. Could be soft rubber hose led from tank is pinched somewhere in route or another restriction. Would definitely account for gen pump not being able to maintain suction with engine running. Main pump would pump cause it's flooded suction. No promises here but another way to look at it.