Trying my luck here...Hot starting woes...

You presumably had your coil tested when cool and off of the car. Unfortunately, it's difficult to check the coil when hot and on the car, unless you have the resistance specs handy and are OK with jumping out and checking it when hot. But, this may be what you need to do. I have experienced the same problem you're now having, only to find it was a coil that was "intermittent." The primary winding was bad, the secondary was good. When cold, it all checked in specs. I chased it for months. Finally, in exasperation, I pulled a coil off another car, put it on mine, and the problem was fixed. It's a relatively inexpensive check, and may well be worth the time. Aside from the ignition, it may be a fuel problem (intermittent injector, fuel pump, sketchy pressure regulator). Work your way through the troubleshooting tree posted somewhere on this site for "no start checklist." Although your car starts and runs OK when cold, the checklist may yet provide a good bunch of ideas, as well. Good luck.

As rrequested...

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.) Coil
B.) TFI module
C.) PIP sensor in distributor
D.) ECC relay next to computer - look for 12 volts at the fuel injector red wires
E.) Fuse links in wiring harness - look for 12 volts at the fuel injector red wires
F.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
G.) Computer

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/articles/electronics/eec-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
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.

Print it or do a search for it.

Also check (I would drop the $8 and replace it) the coolant temp sensor (on the heater hose behind the ALT...mine went bad and gave me HOT start problems. Car failed to idle and cranked for ever before it would start.

Mattys5Oh said:

Wow! Thank you very much! Where on the site is this all posted?? I'll have to check this out this weekend.

Wow, thanks again!!!


Matt

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im not sure what you mean, but the list is JR's. i cant remember if one can print one post in here - so when i get the email notification, i print the email itself with all the info.

good luck.

I don't think it was mentioned, but check your battery cables, I had a problem like this on another car, my ground (negative) cable was bad.

just remember, just because the ends of the wire look ok it doesn't mean the inside is to!!!!!

Mattys5Oh said:

Well for ****s, I replaced my ignition coil and cap n' rotor and it's still doing it.

We also tried the ether and it doesn't start.

My question is, can the PIP (pick-up) go bad only when hot?


Matt

*PS* Also, the car runs great once started, even after it gives me trouble.

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i would find out for sure that you have no spark (ground a plug wire) - that is an easy test and you know whether you have spark or not, as fuel issues can be a little less easy to 'see'.

go from there. good luck.

Your car does the same thing mine does...it starts perfectly fine when cold...but has a weak start when hot and I usually have to give it a few minutes for it to start up...but once started it runs perfect...

Mattys5Oh said:

I will try those steps but I'm just trying a few things too and well I HATE my car!!!! POS!!!!!!!

So far it's not.....

Ignition coil
Fuel problem
TFI module
distributor/PIP (pick-up)
cap and rotor

Wow, this is fun. I'm thinking of trying the engine coolant temp. sensor next.
*By the way, it has started when pop started, but only when pushed very fast (i.e. by another car)*

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coolant temp sensor should have been first to replace as said before..
more likely than not, its your problem.. ford had an outside vendor making these sensors. they are two pieces crimped together..the crimp on a million or so got damaged by the press that put them together . this was a very big
problem discovered in the late 80's and went unnoticed till early 90's.
i myself have replaced a hundred or so back then. some made it 50 miles and some made it 100,000miles but everyone of them i replaced were crimped wrong..i believe you can still find the technical service bulletin reguarding this
problem ..... commonly when the customer got gas they would shut the car off and be stuck home.. they would have the wrecker drop them off to us and they would start right up..from being cooled off..
this sensor basically acts like a choke for the computer to determine how much air/fuel is needed to start vehicle (in simple terms) when the sensor is telling the computer that its 300 degrees it will feed a very lean condition
resulting in nowhere near enough fuel to start veh;
id be willing to bet it will start right up if you let it sit 20min..

My temp. sensor did just the opposite. It told the computer the car was stone cold, resulted in flooded condition. Usually could get it to start with pedal to the floor or jumping the solenoid. Finally replaced it. It was less than 6 mo. old and a mostly plastic unit. Got a real metal one from NAPA. That worked.

Mattys5Oh said:

Well it's been 4 days since I changed the coolant temp. sensor and apparently that's what it was. I want to thank everyone for their help!!!


Matt

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So now your car starts hot like it does cold? or better?...are you talking about the sensor on the lower intake?