Skip to main content ↑ ↓
Topic: Generator Fuel Line Question (Read 426 times) previous topic - next topic

Generator Fuel Line Question

Hello to all. Another question for which I cannot find an obvious answer. I have a problem with my generator shutting off after about 20 minutes and I believe this has to do with a bad fuel line. The generator runs fine without issue, for longer than 20 minutes, if i disconnect the send line from the fuel tank and put a fuel line straight from a 5 gallon diesel can to the fuel pump for the generator. My logic tells me the issue must lie before the fuel pump for the generator, leaving on the send line and the tank itself.

My question is which line is send and which is return from the fuel tank? They are not labeled, both are the same size, and I don't know if there is a way to tell. See photos. I added a photo of the generator for context.

If anyone has suggestions on how to least painfully replace the fuel line that would be great. my thought was to attach new to old and pull through, gently.

Thanks in advance.

Re: Generator Fuel Line Question

Reply #1 –
Those lines are return lines. The supply lines are on the end of the tank. Some are pass side and some are drivers side. Put your coach info and maybe we can tell you which side to uncover.
I took a better look at the picture of the top of the tank and the line with the clamp is the engine supply line
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Generator Fuel Line Question

Reply #3 –
Craneman could the fitting on the top of the tank with the clamp be the vent line? It totally depends on the year, where the supply line is. On most of the ones I have done, seems like the supply line is in the center of the tank, so making removal of the tank.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Generator Fuel Line Question

Reply #4 –
Quote from: red tractor –
Craneman could the fitting on the top of the tank with the clamp be the vent line?

Not craneman but yes as that fitting that you see with a dome top is an Osheet valve and closes if the coach was on it's lid and vents the tank the rest of the time.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Generator Fuel Line Question

Reply #5 –
Sorry, i forgot to mention. 1996 U320. I am fairly certain both of those lines go to the generator, as they both go forward toward the generator. But i would not want to be messing with the wrong lines.

AC7880, Thanks for that. I'll go through it. I'm not sure that is the issue though, as the generator runs fine and for longer when i run straight from a fuel can. if the coolant system was the issue i would imagine i would have the exact same behavior regardless of the source of fuel...

Re: Generator Fuel Line Question

Reply #6 –
Do you have more than a 1/4 tank of fuel in the main tank?
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246

Re: Generator Fuel Line Question

Reply #7 –
We had the same problem on our '93 U300 where it would run for a few minutes and then die. It was air in the system due to millions of tiny cracks in the supply line. If you have the model like ours with the fuel tank on the passenger's side and the generator on the opposite side, it may be easy or not. I bought a roll of fuel hose and a long steel brake line. This was after trying to feed the hose from one side to the other. I disconnected the feed line at the tank (crow's foot) and pulled it to the generator. I connected the new fuel hose to one end of the fuel hose and pushed the other end through the hole that the old line came out from. I left enough hose so when the generator was pulled out, the fuel supply line was not pulled tight.

Our generator fuel line was a little damp to the touch so it was pretty easy to figure out that the air was getting in this way. If you have the 4 cylinder generator, you may have a small valve with a T handle up by the injection pump. If you open it while the generator is running, it will send any air back to the main fuel tank. I usually open it when changing filters, etc. The electric fuel pump will generate about 3 psi when the generator is running.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Generator Fuel Line Question

Reply #8 –
Quote from: mm1313 –
Sorry, i forgot to mention. 1996 U320. I am fairly certain both of those lines go to the generator, as they both go forward toward the generator. But i would not want to be messing with the wrong lines.

AC7880, Thanks for that. I'll go through it. I'm not sure that is the issue though, as the generator runs fine and for longer when i run straight from a fuel can. if the coolant system was the issue i would imagine i would have the exact same behavior regardless of the source of fuel...

Those are not generator lines. As Mike said the one with the tip over valve is a vent and the other is the engine supply line.  In your first photo with the filter is probably the generator filter unless someone moved the engine primary filter there.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean