dumb question?

[masonbytrade]

If a return line to the tank was sucking air would it cause the air to make it back to the supply line?

 

[kipman]

I think no, return line dumps unused fuel back to the tank, pickup gets fresh fuel.

 

[Midnight Rider]

I don't think it would be able to get back into the supply line, like kipman said.

It might pressurize your tank, I guess? Go back and open it up and see if you get a "whoosh" of air coming out.

 

[blzrgb]

 

[stuinnh]

What is the truck doing or not doing that you ask that question.

 

[masonbytrade]

It's sucking ar somewhere and I've replaced 80% of the steel lines and all the rubber hoses from the tank to the injector pump. It will start fairly easy, with a decent amount of gray smoke, but after 10-15 minutes it will start to stumble and lose power. I doesn't die and it seems that if I just drive it in town (30 mph) the symptoms aren't as bad. The only steel lines I haven't replaced are the ones between the lift pump and the filter ( runs in the valley) and between the filter and the injector pump. The air was bleeding through the top of the filter before I put a spin-on one in. What are the common leaking spots?

 

[stuinnh]

The fuel line is a loop, returns excess fuel to tank. Mine had a artic heater so fuel line had 3 way connector with 1 line feeding fuel to the heater. You may need your injection pump rebuilt. seals etc. can go bad from age, and/or sitting and not driven very much. My rebuild cost me $350 with me taking it in and out. I installed electric fuel pump in line after mechanical one. It would start priming system and returning fuel back to tank.

 

[ace]

Put pressure on the tank with a air hose. If you see fuel or hear air coming out of a connection or feed line there is your problem. If not the problem may be a little deeper.