No start when hot !

lilbdfrd

Member
Established Member
Joined
Nov 23, 2012
Messages
30
Location
Kearney,NE
Got a 93 mustang and had to put a Ford racing performance wiring harness in it with a A3M computer. 5.0 5 speed has a new fuel pump and new TFI module. But my problem is car starts and runs great you can drive around for a couple hours but as soon as you turn it off it just cranks and does not start anybody have any idea what’s going on.
 

MG0h3

Well-Known Member
Established Member
Joined
Jul 23, 2014
Messages
13,683
Location
El Paso, TX
Been a decade so I can’t remember the test but it’s quite easy.

Think you just ohm it out. Take you 30 seconds to pop the hood and pull the plug.


Sent from my iPhone using svtperformance.com
 

lilbdfrd

Member
Established Member
Joined
Nov 23, 2012
Messages
30
Location
Kearney,NE
It never does die while I am driving it. And I used the little package of thermo compound that came with. I contacted ford racing and they said it might be a ground issue?
 

CobraSam

Well-Known Member
Established Member
Joined
Apr 26, 2020
Messages
418
Location
Mass
Could be a ground issue, but that really sounds like some sort of heat soak issue in the ignition system. But, where it doesn’t die while you’re driving, that opens up other doors.
I feel a ground issue would happen at any temp and not just when u try a restart. Does it restart after it cools a bit?
 

lilbdfrd

Member
Established Member
Joined
Nov 23, 2012
Messages
30
Location
Kearney,NE
It will restart after it has completely cooled down. And starts like there is no issue‍♂️♂️.Do you think it could be the computer I have an A3M ecu. Thought about using A micro squirt but that $475 to maybe fix it.
 

CobraSam

Well-Known Member
Established Member
Joined
Apr 26, 2020
Messages
418
Location
Mass
Check the pick up inside the distributor .

Good point. It really sounds like some kind of heat soak in the ignition system. Something in the distributor, MSD box heating up, (if u have one), ignition coil would be my place to start.
I wouldn’t start thinking ECU or anything yet.
 

MG0h3

Well-Known Member
Established Member
Joined
Jul 23, 2014
Messages
13,683
Location
El Paso, TX
It will restart after it has completely cooled down. And starts like there is no issue‍♂️♂️.Do you think it could be the computer I have an A3M ecu. Thought about using A micro squirt but that $475 to maybe fix it.

I strongly recommend you diagnose and fix the problem before throwing more parts at it.

When a vehicle cranks but won’t start, you test for fuel and spark. Then you go down a diagnostic path.

As mentioned, your TFI could easily be failing after heat soak.

Regardless, test for spark and fuel and go from there.

Do a quick google search on the testing procedure. I want to say you won’t have fuel or spark when the TFI fails. Been a long time though.


“You’re full of $#!+”
Joe Biden

svtperformance.com mobile app
 

Mustang5L5

Well-Known Member
Established Member
Joined
Jan 8, 2006
Messages
602
Location
Boston, MA
Run your engine codes just for shits and grins. See if a code for a bad ECT sensor pops up.

Next time it doesn't start when hot, press the gas pedal to the carpet and try to start. That signals the ECU there is a flooded engine and will turn off injector pulse. Usually when the car has a bad ECT sensor, this happens and the car will just crank and crank when hot, but start fine once it cools down. A ECT code would be generated.

Not saying this is the issue, but stuff to check before firing the parts cannon off.
 

LSwat

Active Member
Established Member
Joined
Aug 5, 2009
Messages
304
Location
IL
Do you have an inline fuel filter? I had a truck that sucked up a bunch of junk from the gas tank.....clogged filter pretty good and it wouldn't start after it was driven.....sat for a while/cooled down and it fired right up.

But like someone said , definitely wanna see if you have fuel and spark.
 

lilbdfrd

Member
Established Member
Joined
Nov 23, 2012
Messages
30
Location
Kearney,NE
UPdate!!

So I put a new distributor in and a new coil , checked the ground from the harness and nothing still the same no start when it’s hot.

I’m going to go to the parts store and get a Noid light to check and make sure the fuel injectors are getting signal and getting a fuel pressure gage for the line to make sure the psi is correct even though I do have a new pump.
 

Froggy

New Member
Joined
Sep 4, 2020
Messages
4
Location
Ohio
Long time mustang owner but new here.
I have had similar problems in the past and the fix for me was simple.
First thing to try is after you shut it off, try some starting fluid and see if it starts.
If it does then you most likely have a tps going bad and it will get worse before it totally won’t start hot or cold.
 

Tob

Salut!
Super Moderator
Joined
Mar 17, 2009
Messages
12,192
Location
The Ville
UPdate!!

So I put a new distributor in and a new coil , checked the ground from the harness and nothing still the same no start when it’s hot.

New distributor but with the old module? If not, what make distributor? Reman?
 

CobraSam

Well-Known Member
Established Member
Joined
Apr 26, 2020
Messages
418
Location
Mass
I’m sticking to my guns on this one. OP, have you swapped to a known good TFI module? No start when hot is a classic symptom of a heat soaked TFI module.
Does it die on you while driving? If so, that’s more proof of heat soaked TFI.
If you swapped TFI’s, don’t rule out the fact the new TFI could be faulty out of the box. Ask me how I know.
 
Last edited:

Users who are viewing this thread



Top