I have installed a new fuel pump and a pressure regulator. Start the truck it will run for a minute or two with a lot of persuasion. When it begins to die fuel pressure drops down to around 30 lbs or a little below. I have tested the relay checked for full voltage at the pump. Everything checks out scratch head no luck with this truck
Thought of something how about control module

 

water in the distributor cap? need new plugs? has the truck been sitting for a while? more history of the truck helps us all out more

WELCOME to the F150 FORUM!!

 

Around a month old cap rotor plugs and wires. Before I got it a yr ago yes it sit. I have driven and used it. About a month ago it started running bad so I tuned it up. After I was done started the truck drove it around the property ran great. The truck then sit for one week. I started it up about to leave and it ran for 1 minute and died will start back but will only run for around a minute. If you watch the fuel pressure tester it starts out with 42 psi once the engine starts you can watch the fuel pressure falling off when it hits 30-32 it will die nothing you can do to stop it and the fuel pump is running

 

What year? motor?

 

second that!

and, what did you do to it when you tuned it up?

how long has the gas been in the tank...it looses octane after 30 days. If it was 87 it has significantly dropped.

 

He said the pressure is dropping ??

 

installed 8 brand new motorcraft spark plugs. 8 brand new wires, new cap and rotor button, fuel filter truck ran great for a day it sit for a week then the fuel pressure began falling off. it felt like it was running out of gas so I added 6 gallons then i checked fuel pressure when it continued to die off fuel pressure was a little low so i installed a new fuel pump a new regulator anerw fuel pump relay

 

what about the filter?

 

if your truck has two gas tanks, there should be a third fuel pump up on the fuel rail to convert the lower pressure tank fuelpumps into high pressure fuel. one of my friends had a similar problem

 

Inertia switch?