Okay i have a 20r motor and hooked up a mechanical fuel pump worked great but when i needed to hook up the water outlet on the engine it ran into to the fuel pump anyway i took it off and proceeded to hook up an electric fuel pump. Here is the prob i had a 2.5-4 psi pump and it would prime but wouldn't put any fuel into the bowl of carb NO FUEL so i thought maybe there wasnt enough pressure so i bought a 5.5-9 psi ran for a minute and now nothing truck has 1/2 tank of fuel, ran great with mech and now nothing keep in mind this is an 81 truck with the return supply to and from the tank any ideas????

 

I have a 81 with a 20r and it has a electric fuel pump, so if you you take the fuel line of the carb and turn ob the fuel pump and gas comes outm then i would guess you have a carb issue. I have a wber 38 on mine, got rid of the stock carb and all the extra vacume lines.

 

is your gas cap on tight it needs a seal sometimes , also can check to see if your fuel fliters are clogged I went out and bought a new electric pump thinking mine was dead but there was just a hidden fuel fiter by the tank.,