onan 4.0 fuel problems

[bill emery]

 i have a onan 4.0 model # BFA-1R/16004C . i had a problem in the main gas tank of the RV. the fuel pick up rotted away inside the tank. It left alot of small black mesh stuff in the bottom of the tank. I had the carb replaced on the onan and installed a inline fuel filter and changed it every time we went out for the weekend.

 It ran great for a year now i don't have gas in the carb.i replaced the fuel pump, installed a new fuel filter. It just won't fill the carb bowl. it will run if i spray carb cleaner into the carb but i think it is only running on the carb cleaner not gas. what could keep the gas from going into the carb? is there a fuel shut off on the carb? thanks for any help you can give..bill

[Russell E Johnson]

Forgive the obvious questions, but did you drop the fuel tank and replace the pickup hose with the proper type of hose?  Did you have the tank professionally cleaned?  And finally, is the fuel tank more than 1/4 full?

[bill emery]

yes i had to install new fuel pick ups in side the tank. i cleaned the tank and the fuel is at 1/2 a tank now. i have the gen hooked up to a small gas can with gas and seafoam mixed rite now

[Jim Stoltz]

I went through a similar problem with my generator, and ultimately with the engine. The lines hooked up to the pickups at the tank had deteriorated and were sucking air. Nothing would run from the fuel tank despite the fact that I knew I had a full tank. The engine and generator would only run if I connected the fuel feeds directly to a container of fuel. Ever try to get soda through a cracked straw? Same thing. I had to hack a hole in the floor and replace all the rubber lines. All good now.

[bill emery]

 i am thinking about replacing the lines from the tank to genny. if the float valve was stuck closed in the carb don't you think the fuel pump could push it open?

[Russell E Johnson]

It might not if the old fuel sat long enough to turn to varnish/lacquer.  I would try pulling the carb and cleaning the fuel bowl and float.  Since it will run on carb cleaner that means everything from the bowl forwards should be OK.  

Did you run fuel through the hose without being hooked to the carb to make sure that the pump really is pulling fuel from the gas can?

[Don Huntley]

"I am thinking about replacing the lines from the tank to genny"

Just did this on my '87 for the same reason! Tiny nick in the fuel line where it clamped to the fitting at the tank

[bill emery]

 yes it will run fuel thru the line from the pump to the carb just not into the carb. i removed the line from the pump to the carb and turned the pump on and pumped gas into a cup. the genny was running last weekend all day sat then just stoped

[Jim Stoltz]

Will it run from a line into a gas can? Mine did something similar. It seemed like it would pump some fuel up, but not enough to keep it running. The problem started with it running for hours at a time, and then dying suddenly. The run time got shorter and shorter until it wouldn't run at all. It would run all day long out of a 5-gallon can with the fuel feed dipped into it.

[bill emery]

no it will not run with a line from a gas can. how hard is it to remove the carb? if i take it apart and clean it out will i need a tech to reset all the jets and setting?

[Jim Stoltz]

Honestly I don't know. I've never messed with mine except to change the fuel filter and plugs.

[bill emery]

Pat i can get it to run on carb cleaner as long as i keep spraying into the carb., it has a new fuel pump that is pumping gas up to the carb from a gas can. i can't see down the carb because it is mounted inside the RV compartment. pulling the whole genny out looks like a big job

[Jim Stoltz]

The problem has to be the carb itself then. Either float, something stuck in the needle valve, or something stuck in a passage. I've had success in hooking compressed air up to the inlet, but you do run the risk of lodging whatever it is deeper into where ever it's lodged. Most of the time, however, it will blow out and you'll be good.