I'm ready to sell this ship anchor !

[lmk]

My 90gt was running great, then a month ago it dies in traffic. At home I can sometimes get it started but I have to rev it to 3000
to keep it going, as soon as I take my foot of the gas it abruptly dies. When I turn the key to the on position it will prime the fuel pump then a few seconds later it primes it again and again and again.But my fuel pressure is holding at 40 psi. What would cause
it to continually prime the pump without turning the key off and back on again? ...So far these are the parts I've changed

Coil
stator in distributor
ignition module
wires
plugs
computer
eec relay
fuel pump relay
ignition switch
fuel pressure regulator
fuel filter

The only code I get is a 15

I don't know where to go from here any ideas.....lmk

[82 GT]

Try changing the engine...LOL Seriously, maybe it's the TPS
Did you try and reset the computer?

[88workcar]

SHIP ANCHOR........ Thats the Mustang spirit buddy.

Try the tps. And check if you have water in the oil.

[tmoss]

Probably the TFI - a guy on another board just went throught the same thing - he even had the TFI checked and was told it was OK, but as soon as he put a new one on his problem stopped. The TFI often fails when warm but is OK cold, hence the good test at a store.

[Coupe50h]

If your fuel pump keeps running, you need to check it's wiring, also, does your fuel pressure hold with the engine off, key on or off?

[Capri306]

Originally Posted by lmk

When I turn the key to the on position it will prime the fuel pump then a few seconds later it primes it again and again and again.But my fuel pressure is holding at 40 psi. What would cause
it to continually prime the pump without turning the key off and back on again? The only code I get is a 15

Maybe YOU aren't turning the key on and off, but it is very possible that your ignition switch could be. If it's faulty, it could be making intermittent contact -- just enough time for the relays to close the circuits. Then, even something as slight as vibration from the engine running could be causing the connection in the ignition switch to be lost. I'd pop the column covers to see if there's evidence of heat damage, and then use a DVOM or test light to check for power failure at proper points on the switch.

This problem has puzzled me, because you've already replaced most of the parts that commonly go bad or come to mind.

There is NO WAY a faulty TPS is going to cause your fuel pump to turn on and off, btw. The EEC-IV is in control of its operation via a relay and the power supplied to each; it doesn't care whether the TPS is out of range as far as fuel pump control is concerned, which should be your main priority right now.

By your wording, you say you can turn the key to the 'on' position, and the fuel pump will continuously prime, correct?

There HAS TO BE a power interruption of some kind for this to happen (without the engine running and then stalling). You've already hit the fuel pump and EEC relays, so that takes them out of the equation. I believe you have a wiring or related problem; somehow the 'chain' is being broken here. It could very well be as simple as a loose/corroded connector on one of those relays. I've fixed several 'problem cars' looking for this type of thing. Check all of your grounds as well as fusible links and power feed wires.

FWIW, your code 15 means (according to this one guy's site, anyway):

15 (O) No Keep Alive Memory power to PCM pin 1 or bad PCM (Memory Test Failure)
(M) KAM (pin 1) was interrupted (was battery disconnected ?)

This further proves the likelihood my theory that the computer losing power somehow, somewhere, is correct.

Good luck.

[82 GT]

Good point.....since Ford ignition switches are prone to go bad.

[tmoss]

KAM is fed from a 20guage fusable link that also feeds the EEC relay (power side - fuel injectors, MAF, IAB, Thermactor, EGR).

[aar0s]

wasnt there a tsb on the ignition switch? might see if you cant get a dealer to do a recall on it.