Getting air in fuel system

[RunMonkeyRun]

I finally had a chance to look at the truck this weekend and when opening the fuel filter there was no fuel. I added fuel and the sun of a gun started but I am getting air in the system, so it shuts off. What is the best way to try and hunt down where I am getting air?

[Robyn]

Hello
The pump is under the rig slightly behind the driver seat. Anything forward of that point is under pressure.
The issue has to be aft of the pump between there and the tank.
Is this a single tank vehicle??
If its a SUB or a single tank pickup it is a bit more simple. You may want to drop the tank and start with the pickup tube inside. I would replace the pickup as they have a sock anyway that can get pluged. The lines coming forward are steel except where they hook to the tank.
Look the entire system over from the tank for any signs of damage in the steel lines too. A spot that has rubbed against the frame could have a hole.
Easiest way to test the full system is to use another electric pump. (the parts store sell the cheapies) hook the pump up to the line going up the frame and use a small fuel can full of fresh diesel. power your test pump with some jumper cables and then look for a leak. If you pressure the entire system and there is no leaks then it has to be in the tank. A suction side leak may not show but a pressure side one will. OH BTW if this rig has multiple tanks then the switch valve is to be suspect too.
Good luck
Robyn

[RunMonkeyRun]

I have 2 tanks in this rig, is it possible when I fill the bowl with diesel it drains back into the tank? I had noticed on the pump it was by chance the the hose on the right of the pump when I moved it I heard a burst of air. Saw some fuel with come out of it so I fixed that problem but still wouldn't stay running and still getting air in the fuel.

[RunMonkeyRun]

Let me ask this, what is the best way to bleed air out of the fuel system first?

[RunMonkeyRun]

Hello
The pump is under the rig slightly behind the driver seat. Anything forward of that point is under pressure.
The issue has to be aft of the pump between there and the tank.
Is this a single tank vehicle??
If its a SUB or a single tank pickup it is a bit more simple. You may want to drop the tank and start with the pickup tube inside. I would replace the pickup as they have a sock anyway that can get pluged. The lines coming forward are steel except where they hook to the tank.
Look the entire system over from the tank for any signs of damage in the steel lines too. A spot that has rubbed against the frame could have a hole.
Easiest way to test the full system is to use another electric pump. (the parts store sell the cheapies) hook the pump up to the line going up the frame and use a small fuel can full of fresh diesel. power your test pump with some jumper cables and then look for a leak. If you pressure the entire system and there is no leaks then it has to be in the tank. A suction side leak may not show but a pressure side one will. OH BTW if this rig has multiple tanks then the switch valve is to be suspect too.
Good luck
Robyn

Thanks for the info Robyn, I will be testing this today or tomorrow, where is the switch valve? I do have 2 fuel tanks.

[Robyn]

Not sure on that rig.
Most likely in the back between the tanks probably on a crossmember or frame rail. (Its easy to find, just follow the fuel lines untill ya find the little creature)
The switch valves can be a PITA for sucking air.
Does the rig have the problem on both tanks or just one??
keep us posted
Robyn

[Robyn]

Getting the air out is easy.
run the electric fuel pump and open the ait bleed on top of the filter. Run a hose to a can and let the fuel run untill its free of air.
The IP will purge itself in short order