Engine wont start

when my fuel pump went out in my 89, it wouldn't idle. I could revv it up to 2500rpm to keep it running if I let off the gas or put it in drive (AOD) it would die. Could be that the bad gas, or the fuel pump could be bad. Fuel pump replacement isn't hard. I believe you can check the voltage to the pump to see if its bad....but if its still got the stock pump it will need replaces soon anyway. Goodluck man and congrats on getting a 5.0

Following was written by jricker:
Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/article...c-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. A tire pressure gauge can also be used if you have one - look for 37-40 PSI. Beware of fire hazard when you do this.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – press reset button on the inertia switch. The hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

The electrical circuit for the fuel pump has two paths, a control path and a power path.

The control path consists of the inertia switch, the computer, and the fuel pump relay coil. It turns the fuel pump relay on or off under computer control. The switched power (red wire) from the ECC relay goes to the inertia switch (red/black wire) then from the inertia switch to the relay coil and then from the relay coil to the computer (tan/ Lt green wire). The computer provides the ground path to complete the circuit. This ground causes the relay coil to energize and close the contacts for the power path. Keep in mind that you can have voltage to all the right places, but the computer must provide a ground. If there is no ground, the relay will not close the power contacts.

The power path picks up from a fuse link near the starter relay. Fuse links are like fuses, except they are pieces of wire and are made right into the wiring harness. The feed wire from the fuse link (orange/ light blue wire) goes to the fuel pump relay contacts. When the contacts close because the relay energizes, the power flows through the contacts to the fuel pump (light pink/black wire). The fuel pump has a black wire that supplies the ground to complete the circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/t...witchWiring.gif

http://www.veryuseful.com/mustang/t...inks-ign-ac.gif

http://www.veryuseful.com/mustang/t...91eecPinout.gif

Now that you have the theory of how it works, it’s time to go digging.

Look for 12 volts at the Orange/Lt. Blue wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring or connections. There is a mystery connector (one I haven’t found) under the dash somewhere, between the fuel pump relay and the fuse link.

Turn on the key and jumper the fuel pump test connector to ground as previously described. Look for 12 volts at the Light Pink/Black wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed or there is a broken wire in the relay control circuit.
Check the Red/black wire, it should have 12 volts. No 12 volts there, either the inertia switch is open or has no power to it. Check both sides of the inertia switch: there should be power on the Red wire and Red/Black wire. Power on the Red wire and not on the Red/Black wire means the inertia switch is open.

The Tan/Lt Green wire provides a ground path for the relay power. With the test connector jumpered to ground, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the Tan/Lt Green wire. The test light should glow brightly. No glow and you have a broken wire or bad connection between the test connector and the relay. To test the wiring from the computer, remove the passenger side kick panel and disconnect the computer connector. It has a 10 MM bolt that holds it in place. With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow. No glow and the wiring between the computer and the fuel pump relay is bad.

If and only if you have followed the test procedure to this point and still haven’t found the problem, the computer is suspect.

(copied from a thread posted in by jricher via search)

I would bet on the gas too. Or, having sat so long, the injectors may be sticking a bit. There was a thread a few days ago about some inj cleaner that you run in through the schrader valve. If you can keep it running long enought to get that in...but if you have a couple inj that are stuck shut, then no amount of cleaner will help till something flows through. Get the old gas out of the system first.

I have a similar situation with my 89. I replaced the fuel pump about 6 years ago with whatever Autozone had to offer. Sometimes the car starts and sometimes it doesn't. The sound from the fuel pump is slightly different than my other 89. The other 89 has a Holley fuel pump. When I turn the key on it the pump turns on and whines and continues to do so untill I start the car. The stang I'm having the problem with only whines for about 3-5 seconds then stops. I checked the battery it's fully charged. I checked the coil wire with the screwdriver and it has spark. The only thing I haven't checked is the wire ball nect to the ignition coil and suppressed diode. I would think with coil fire and juice it would turn over but it won't. Occasionally it sounds as if it is attempting to start but doesn't turn over. Like I said it's intermetant. One day it'll run great the next dead as a hammer. I'm really not looking forward to replacing the pump if it's the problem cause I'm short on cash, the tank is full, and I'm trying to sell the damn thing. Almost make me mad enough to kick it.

I got mine running again. I noticed it was wet or raining when it didn't run. Must be a damn short somewhere. Figgures. Off to chase a wire demon.

The last time I replaced the pump I just siponed it out. There is a reserve area that holds a little fuel for the electric pump but if ya wiggle the hose around it'll get most of it.

Talk about a canidate for Overhaulin on TLC.

Dude, if you did not completely flush the fuel system then you're not going to get anywhere till that garbage in the tank/lines burns up. Even gas that has sat for only 4 months will turn a good running motor to holy crap. You need to disconnect the pressure line from the pump at the fuel rail in the engine bay, and let the fuel pump run till it has pumped out everything in the tank... (if you already filled up like a 1/4 tank to full with fresh then you can just run it till a half gallon or so comes out)

Do not waste time tracking down "problems" till the car is running on new gas.

ok so I neglected to read the thread in entirety before replying

if the engine itself idles smoothly as observed from under the hood... then it's okay.