03-05-14 I first posted this problem. Can't find original post to refer to so to recap it eventually started after about a half-hour and I drove it home and tried to replicate the problem over a few days but could not.
Jump to May 15th or so it happened again and this time it came home after a $200 ride on a roll-back flatbed.
Condition lasted a couple of days and it started. Never threw a code. I have the factory Powertrain Control and Emissins Diagnosis book with the pin point tests etc. What a maze.
Anyway found a real nice universal fuel injection pressure tester kit from Actron for $60 (Ford wanted $180 for just the guage and hoses) and hooked that up and the pressure was OK.
So it failed again in the shop. Pump did not come on so no pressure but cranked good. But then it did come on and it started a day later.
So I'm thinking electrical because once a pump fails it's done, right? it can't fix itself can it? Read on my friend...
So as the PCM is the controller of the fuel pump relay I had to wring out the voltage path of all the circuits thru all the inline devices to the fuel pump.
After it failed again a week later (I kept testing it many times a day) I had identified all the wiring and connectors and traced the voltage all the way through the relay, the voltage to energize the relay and the voltage thru it and thru the Inertia Shutoff Switch to as close to the pump as I could get and guess what?
There was voltage in the wire going over the top of the fuel tank to the pump but it was not running!
So after being derailed a bit by the 2 second run time of the pump on key on and swearing it was the relay (who puts a relay behind a radio anyways?) that was bad but figuring out that it was OK after pulling the radio..
Bad fuel pump, a intermittent bad fuel pump?
Having dropped fuel tanks before and the tank was almost full, the bed came off the truck. Six bolts, (8 for a longbed) the fuel filler's three screws and a couple of electrical connectors and the tank was right there like on a bench to work on.
So far all is good with the new pump.
Unless it's one of the many sensors that feed info to the PCM... The PCM doesn't control the starter does it?
The old pump's windings resistance does change a few ohms when it is tapped so there is something loose inside. Haven't had time to disect it yet.
Sometimes old school methods are the best.