1990 LX dies and will not restart when warm!

When it won't start, it'd be nice to know if it was missing spark, fuel pressure, etc. Pulling codes is also a good idea.

Otherwise, we're going to be taking huge guesses.

Good luck.

i'm guessing fuel pump getting hot or the tfi module is getting hot and loosing spark, i've had my car miss and i've also had my car die when the module went !

89lxcoupe said:

i'm guessing fuel pump getting hot or the tfi module is getting hot and loosing spark, i've had my car miss and i've also had my car die when the module went !

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I Agree. My 88 Notch would run fine when first started. It would run fine till shut off. If I tried to restart the engine (like after getting gas) the car would not start. I had spark but no fuel pump. I tracked the problem down to a faulty fuel pump.

Good Luck

I had the same problem. While I was driving and stop for gas wouldnt fire back up. Did it to me 3 times in one day. I let it sit over night and then worked great for a couple weeks give or take and now it wont stay running for more than a few seconds. However I believe my problem is my computer got shorted out. I have my new A9L and as soon as I get it in i will let you know if that was it.

Can you hear your fuel pump prime when you turn the key? There is a fuel pump test connector on the Self Test connector. Ground it and then turn your ignistion on and go to the back of the car. You should be able to hear it pumping. Do a search for trouble pulling codes and look for jrichker post. It will be in there.

GOOD LUCK

I had my crank sensor do a similar kind of dealio...
It took like... 2 weeks of going back and forth to the shop before they finally figured it out... :/ grr...

Good luck buddy.
-a

ive had the same problem went through many relays and starters and ground wire tfi module and finally i just got used to popping the hood and jumping the relay to start after warm smtms it does it sometimes it dont

Adams91LX said:

I had my crank sensor do a similar kind of dealio...
It took like... 2 weeks of going back and forth to the shop before they finally figured it out... :/ grr...

Good luck buddy.
-a

Click to expand...

ididnt know 5.0s had a crankshaft sensor ?

sjhm9102 said:

ididnt know 5.0s had a crankshaft sensor ?

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That's because they don't. Your symptoms point to a faulty TFI or PIP/stator. Both tend to go bad as they age and both can cause these very symptoms. If you have fuel, but no spark, it points to the TFI. If you have no fuel or spark, it points to the PIP. If you loosen your distributor hold down and rotate the distributor, do you hear your fuel pump prime? The PIP signal tells the computer the engine is running when the distributor is turning, which in turn activates the fuel pump.

do i need a new distributor to get the pip/stator or is this a local autoparts item? i need an excuse to get an msd distributor haha

how about your coil? I had a car that did the same thing as what yours is doing and it was the coil. Run the car til it dies and check for spark. Also I had my ignition module that did too might want to check into that also.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Revised 18-Oct-2006 to include TFI fault during crank/run cycle
All text applies to all models unless stated otherwise.

Note: 94-95 specific changes are in red

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the 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. See paragraph 3A - a noid light will tell if the pip is working by flashing when the engine is cranking.
E.) No ECC or computer power - ECC or computer relay failure
86-93 models only: ECC relay next to computer - look for 12 volts at the fuel injector red wires
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
F.) No ECC or computer power - fuse or fuse link failure
86-93 models only: 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.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
H.) Computer
J.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI.

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
Computer/fuel pump/ignition wiring diagram, 86 model http://www.autozone.com/images/cds/gif/large/0900823d80167158.gif
Computer/fuel pump/ignition wiring diagram, 87 model http://www.autozone.com/images/cds/gif/large/0900823d8016715e.gif
Computer/fuel pump/ignition wiring diagram, 88 model http://www.autozone.com/images/cds/gif/large/0900823d80167162.gif

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars
Computer/fuel pump/ignition wiring diagram, 89-90 cars http://www.autozone.com/images/cds/gif/large/0900823d8019595f.gif
Computer/fuel pump/ignition wiring diagram, 91-93 cars
http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_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 Upper RH corner to ground.


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.) 86-93 models only: 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.
94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
F.) Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the 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.

i would check all your grounds and make sure there good. phil

donsbad68 said:

Update! New alt. wiring, new distributor, new Tfi module. Problem still there. What do you think check next? There are no codes. Fuel pump? coil?

Click to expand...

When the car failed, what did your testing show? Jrichker's list 'is what should be checked next'. That's going to be the easiest way to figure out the issue, and do so without replacing random parts.

Good luck.

Fix your hot cranking problems first and the other problems may go away on their own.

Notice the section on using a voltmeter to check the quality of connections. I would read it very carefully and test all the starter power & ground wiring.

Here's a checklist:

Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…

Check battery, terminal connections, ground, starter relay switch (also known as solenoid) and starter in that order.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection: more than .5 volts across a connection indicates a problem.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103 for help


1.) Will the car start if it is jumped? Then clean battery terminals and check battery.

2.) Check the battery to engine block ground, and the ground behind the engine to the firewall.

3.) Jump the big terminals on the starter relay next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

4.) Then pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it starts, the relay is good and your problem is in the rest of the circuit.

5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.
Typical start circuit...



See http://www.autozone.com/images/cds/gif/large/0900823d80195963.gif for 88-90 year cars .OR see http://www.autozone.com/images/cds/gif/large/0900823d80195964.gif for 91-93 year cars. See http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-95 model cars.

6.) The starter may be hung, loosen up the bolts that hold it on, and give it a good whack with a big hammer. Tighten up the bolts and try again.

7.) If that doesn't work, use a jumper cable from the positive lead on the battery direct to the starter post where the big wire from the relay connects. If it cranks then, it is the power wire from the relay gone bad. This will be hard to do, since there isn't much room to do it.

8.) Pull the starter and take it to Autozone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.

dangit...
i forgot that was the summer i had my 4cyl mustang... balls... hate it when i do that...
-a

This happened to me too i would drive it for like 3-5 miles and it would leave me on the side of the road....this happened twice.

I have an MSD dizzy so it doesn't matter what kind you have it will happen to everyone in due time. If you want to buy a new dizzy it will fix the problem but if you want to spend less that $20.00 go to auto zone with the dizzy taken off and they can test the TFI module for you and if it reads ok its the pick-up coil PN#F122. I've had to replace mine when this happened and the car has been running great every since. I called MSD because i thought they made one but they use a stock piece so i just got it at the zone.

You will have to remove the holding pin and gear to get this done. I should have taken picks but i just wanted to get her running again..
http://www.autozone.com/servlet/UiBroker?UseCase=C001&UserAction=performMoreDetail&Parameters=TRUE%7C%7EPick-Up+Coil%7C%7ENONE%7C%7EWELLS%7C%7ENONE%7C%7EFALSE%7C%7EFALSE%7C%7E184572%7C%7E3516%7C%7EF122%7C%7EThe+distributor+must+be+removed+to+install++++++++++++%0Apick+up+coils.%7C%7E%2417.99%7C%7EFord%7C%7EMustang%7C%7E1990%7C%7ENONE%7C%7E0.1%7C%7ENONE%7C%7EB

Good Luck
Benny