I posted this on the general section before I realized it would be more appropriate here. I seldom have problems with the old girl. It is a daily work truck. This morning she shut down at a light. No restart. Changed the fuel filter, she ran for a few minutes and shut down again. When I bled the filter cap I got lots of air but it wouldn't bleed out. I replaced the lift pump. Same problem. So I took the line off the input side of the lift pump an connected the pump straight to a fuel can. Bled out fine and ran good. So obviously I have a problem with the chassis side of the fuel system. I had replaced the selector valve a few years ago so I'm thinking the problem is in the feed line inside the tank. Has anyone else seen this before? I haven't had a tank out of this truck before so I don't know what the pick-up in the tank looks like. It is 3/4 full.

Dave

 

Broken showerend on the pick up in the tank or pin hole in the line either on the way from tank or the pick up tube in the tank.

 

hmm .. well i think i would take run fuel hose straight to the incoming side of the fuel sv feed .. and run it to determine if it's before or behind that point ..

divide and conquer .. no need in dropping the tank if it's debris lodged past the fsv ..

also could be something clogged in the fsv itself ..

if it pulled ok straight from the fsv input bypassing that point forward .. then i would take the hose from the input of the lift pump and gently push low pressure air into the hose to try and dislodge what is plugging it up .. switch the fsv and purge again with compressed air low pressure ..

if it doesen't pull directly from the input of the fsv .. then you know you got a problem in the pickup or in the tank and gonna have to drop it ..

or before doing that again try pushing low pressure air to dislodge what is stopping it up ..

also now would be a good time to install small little fuel strainers like the kind ahead of the carbs you see on race cars .. not full blown filters but little strainer deals just before the fsv .. to keep from plugging the system again if junk from the tank gets into there .. my fsv is stuck again .. but rather then replace it i'm gonna take it apart and clean it and install fuel strainers also to keep something just like this from ever happening ..

 

or if it's not debris .. like romel said .. a hole somewhere .. it's sucking not pushing .. so it will suck in the air first .. in that case maybe if the leak was big enough you could force light air pressure into the line with the fuel system all still connected and if quiet enough listen for air escaping or rub dish soap on the lines looking for bubbles .. i guess i would do that first so as not to get a fuel bath if it were a hole towards the front and no need to get into the tanks or fuel supply lines

 

Thanks, I like the idea of low pressure air back through the system. Hopefully it will be a pinhole in a line so I won't have to drop the tank.

 

Does it work on either tank?

With key on, engine off, when you switch tanks, do you hear the valve operating? Do you hear it going both ways on the switch?