I was having problems with my 90 f150. One of the tail lights would stay on like I was hitting the brake but the other one would not cone on at all. Except for the blinkers both blinkers works. Very weird. I replaced the bulbs and the sensor that's on the brake pedal and that fixed that then the next day I cranked the truck up and as soon as I got out of my driveway it shut off. I did a little research and determined it was the ECM (engine control module). I replaced that and the truck cranked up and ran good but shut back off after a couple minutes. I cranked it and it shut off 3 times. I then removed the brake sensor I had previously replaced and tried to crank the truck. It cranked up and idled well for about 10-15 min. I put the brake sensor back on and I drove it maybe 200 yards back to my house and shut it off thinking all was well and everything was fixed. The next morning I cranked it up to go to work and it idled for a min or two and shut off. Now it won't crank at all no matter what I do. If anyone has ideas please let me know I need help this is my daily driver. Thanks.

 

Welcome to the site..

Have or can you verify the fuel pump run, and a hot/active spark?
When the key is cycled to ON, pump run should be 'heard' for a few seconds as the system pressurizes. (PCM is in control of fuel pump relays grounding= run and times) Even if present, not a bad idea to verify fuel pressure and volume..

The intermittent run I'd doubt is related to brake lamp function, short etc.
Would be fairly common for a pump fail, pump relay etc to be or cause an intermittent and should be proved out. Same with an ignition/spark drop out.. Checking the two systems are functional would be my first step, and if both are present, checking for an injector pulse provided by the PCM..