Yes, low pressure in the tank and high pressure on the frame. Is there a particular pump i should focus on or doesnt it matter it could be either one. Can these pumps be tested before wasting money on the wrong pump.

according to my chiltons manual the spec for idle is at least 30 psi to run properly at idle. a few psi lower and you'll have running problems. if only a few psi total then it wont start. if the pumps dont prime to at least 30psi then you'll have to see which pumps arent working properly. you have a low pressure intank pump and a high pressure inline pump on the frame rail right?

ok then your not getting enough gas into the engine. what was the pressure at the rail? or did you just check and see if there was pressure there? if thats the case then you need to actually check the pressure with a gauge.

what do you mean prime intake? giving it some throttle? is it carburated or fuel injected? if fuel injected then just crack the throttle open a little bit, if it starts then it sounds like the iac is sticking. if you have to push it to the floor to start it then it means that there are leaking injectors.

1989 F150 4x4 4 speed manual shift. This truck was rear-ended and all repairs were fixed accept the problem of not starting. I checked both fuel pumps and they are working. I've replaced the fuel filter and checked the fuel rail pressure valve and there is gas at the rail. Now heres the catch, if i prime through the intake the truck will run fine until it runs out of fuel. If i rapidly push the gas pedal it will cough , fart and buck and once i stop the rapid pedal stomping it idels real high and then dies. Try to restart and it will only fire and die and after a few tries and then it wont fire at all until i prime it again. If its not my fuel regulator what else could it be, the entire fuel rail??????????????? WEAK HIGH PRESSURE FUEL PUMP, i'm lost and i've got to much time and money invested to just give up and walk away can anyone help.