Intermittent Fuel Delivery EFI

[DaRey8126]

I recently replaced the fuel lines (tank to fuel rail), fuel pump, fuel filter, and fuel tank on my 91 Vert 5.0.

Prior to replacing the parts I had intermittent priming of the fuel pump when turning the key to the "on" position.

Occasionally when starting the car, it acts like it is starved of fuel. It starts and immediately dies. This will repeat half a dozen times until it starts and runs normally. This happens very infrequently and only seems to occur when starting the car, not while running.

I can hear the relay under the seat, even when the fuel pump doesn't prime.

 

[broncojunkie]

Two things come to mind.

For starters, a lot of fuel priming issues can be caused by a bad ecm. Have you checked or dealt with that yet? They all go bad, eventually. It's usually the capacitors and they can be repaired for a few bucks in parts and by someone who knows a few soldering tricks.

Second would be the ignition switch. I replaced the switch in my 88gt several yrs ago as part of a revival. The car had sat for a decade or two. Tank, pump, and hangar were completely rotted. Ignition system was bad. It had wiring issues, etc. The car was always hard to start and no matter what I did, nothing seemed to help. It would fire right up and immediately die. I eventually realized that I could keep slight pressure on the key with my thumb as I was letting the key return to the "run" position. That is, I wouldn't allow it to spring back on its own. There was obviously an issue with the new aftermarket switch. I had a laugh and left it as-is, since it created a bit of a theft deterrent. My friend owns the car now and still drives it regularly. I had to show him the trick, of course.