in tank fuel pump?
 

did the 89,90,91 f350 7.3l have any in the tank pumps? or anything to cause a restriction?

Nope, the IDI used only a block mounted pump. The gas trucks had in tank pumps.

only restricion if pickup screen got clogged somehow.

maybe the tak selector valve is toast?

could be. unhook it and bypass the lines around it to test.

how do you unhook the lines any special tool? they look like nylon tubbing like air brake line how would you bypass it, i have an extra valve but it hooks up with rubber hose i need to get this truck running asap for hauling

i didnt need special tools to unhook my lines. just slide the little clip out of it and pull the fitting off. clip will be a different color plastic.

oh ok thats what that is any i will try that tonight to see what happenes

ok i was aable to take the lines off the valve and you can blow threw all 6 ports just fine, my budy also said that he has had to replace his in the tank pumps on his 95 powstroke, i thought the diesels did use them

Everything on the PSD is electronic, the IDI's are all mechanical.