86 F350 with dual tanks, it's got a 429 with a mechanical fuel pump,changed from a 460 with mech pump. I'm not getting any fuel to the carb. I've changed the pump and the filter and all new hoses from the pump to the carb. My question is.......can the valve on the fuel rail get stuck in the middle and not let fuel flow from either tank? I hooked up a cheap electric pump pulling fuel from a gas can on my floorboard to get it home, ran fine that way.

 

Seems like I remember having to replace a in-tank pump on my 1986, or is my memory failing me?

 

Mine doesn't have an in tank pump.

 

Still working on it but have narrowed it down to a bad fuel pump from the store........I think. I'll be replacing it again tomorrow. I got a cheap in line fuel pump and set it up to hook to the battery with alligator clips and pulling fuel from a gas can, it runs fine that way, I can drive anywhere I need to this way. So, I tried pulling fuel from the tank with the mechanical pump again, no go. I then started started trying to change the selector valve to install a new one and found out I have to drop the front tank (why couldn't they have put the damn thing 8 inches further forward on the frame rail, IDIOTS!) and gave that up for the time being since the tank is full of gas. I'm still changing the valve since I have a new one but it can wait for now. I then spliced in a chunk of fuel line bypassing the valve and started the truck with a full fuel bowl and no fuel was coming from the tank leading me to believe that the brand new pump is bad. It's either that or a plugged fuel line upstream of the valve, which will get blown out before getting hooked up to the new pump. If it still down't work I'm blowing the truck up, lol.

 

did you try putting the electric pump in the line where the valve was to see if the problem is in the tank, or lines?
if it fires up and runs fine with the e-pump in place of the valve, it is a defective mechanical pump. if it don't run, the problem is in the tank or lines between valve and tank.

 

After the mech pump change and no change I need to try some new lines, or at least try blowing out the old ones.