91 LX Will Not Start.

Rick's Fords said:

Another question while I'm at it, there is a fitting on the fuel line that lookes like a tire stem, does this need to be pressurized after having disconnect fuel lines in the back? What is it's purpose?

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that sounds like the place where you mount a fuel pressure guage.

I was having the same problem with my 92 5.0L but mine wouldn't start when it was hot.
Maybe you should try swapping your TFI module for his and see if it starts.

If his FP stays on constantly in 'run', I would look for a short to ground on the ground wire to the FP relay. This wire could have been shorted for diagnostics by someone, as it is in the self-test connector to assist with testing.

Good luck.

The TFI module mounts on the distributor on models made before 94.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) Coil
C.) TFI module
D.) PIP sensor in distributor
E.) ECC relay next to computer - look for 12 volts at the fuel injector red wires
F.) Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
H.) Computer

See the following links for wiring diagrams...

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars


2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.
Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.

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. Beware of fire hazard when you do this. In pinch you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & 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. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay. The fuse links live in the wiring harness near the starter solenoid.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

Fuel pressure OK, the injectors are not firing.

A.) A Noid light available from Autozone, is one way to test the injector wiring.
B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.

a.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
b.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
c.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the ECC relay and the red wire for the 10 pin connectors.


4.) Spark & fuel pressure OK.

A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently).
D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
HO & 351W 1-3-7-2-6-5-4-8
Non HO 1-5-4-2-6-3-7-8
E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.

haha, welcome to my boat. exact same problems. try the eec relay.... thats where i think that my problem lies.
I have trouble shot everything, im down to this....

As said, the injectors get 12 volts key-on constant power via the EEC relay. The puter pulses ground since it is easier to modulate and less stressful.

I would go back over things you already checked. Having fuel come out of a Schrader valve vs having proper pressure is a big deal. If you go down JR's list again, you will find the issue.

Good luck.

I believe if you take the EEC relay out, or remove the EEC fuse or something like that, the fuel pump will just run and run when the ignition is on. It will have spark but no injector pulse. That's probably not what it is because you have pulsing ground to the injectors. But do you have constant 12v power to the injectors with the key on?

Rick's Fords said:

Do we have MAP sensors? A buddy was saying his car had the same problem, and that was the solution.

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Mass Air cars have a BARO sensor.

Go back to the check list, and start at the top and work your way down. If you do that and don't skip any steps, it is 99% effective in finding the root cause of no start problems.

I just went through this with a 2.3. Cranked but no start. Put a timing light on it and had spark at the right time. Put a fuel pressure gage on it and had no fuel pressure.

I put gas in it and it fired. Would start but barely idle. Black smoke out of the tailpipe, I still have several spots on the driveway.

The car would not flash the CEL with codes.

JR told me what to look for. The puter was fried. Fixed that and got codes.

The MAP was dead, fixed it and we're alive and well.

I would try the timing light thing and fuel pressure check, and definitely getting codes before anything else.

Rick's Fords said:

Well I did some more reading, turns out the injector harness is only supposed to have ground while the car is running/cranking, and it pulses... thanks Mr. Advance Auto Guy.

So tomorrow I will check if it has ground while cranking, if not, I'll put my EEC relay in it.

A quick question, which I think I already know isn't possible, but a 89 computer w/o MAF, can it be put in a 91 w/ MAF.

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all 89 5.0's were maf