Engine 90 Mustang engine swap - starts and stalls

nepats1973

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I have a 90 GT with a replaced .30 bored out 302. E303 cam. Aluminum heads, roller rockers, and new valves. Stock throttle body. New IAC, TPS, brand new distributor, compression checked, spark tested, injectors tested, back probed in and out of car, new fuel injector harness, Ohm checked PIP. I have replaced everything I can think of or read about. I have sent my computer off to be rebuilt twice. New 24lb injectors with matching MAF, 39lbs of fuel pressure at spout. New fuel pump & filter. Replaced all fuseable links. I ran the "no start checklist" multiple times. Replaced all of the relays. The engine starts every time and immediately stalls. I monitored fuel pressure during start and it is within specs. Fuel pressure regulator replaced, vacuum within specs. I spray starting fluid in intake and engine stays running. Removed all salt and pepper connections and soldered wires. Engine code returns 11. Any thoughts? Vehicle ran before engine swap.
 
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90sickfox

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Have you tried holding the pedal to the floor while starting ? Not pumping the gas but on the floor..

If it starts with ether it's usually a fuel problem. Are you sure the injectors harness is wired for the HO firing order ?

The fuel pump should prime and then continue running after start. The PIP controls the injector firing. It is down inside the distributor below the rotor button plate. Make sure that the windows and the sensor itself are in good shape. You could also jump the fuel pump self test wire ( single connector ) that goes in the code reader. I can't remember if it's supposed to get power or ground to jump it. It'll make the pump run continuously. If it makes the car run start looking at the fuel pump circuit.
 

nepats1973

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Accelerator to floor does not work. Old distributor and brand new (not rebuilt) distributor with all new components. Back probe tested each injector and labeled them for proper firing order. Jumpered fuel pumper to constantly run with no change in starting.
 

General karthief

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You're stabbing in the dark. You need to do some testing before you start swapping parts/stuff trying to accidentally fix it.
I suspect you are losing power or ground to the injectors.
If you put a noid light on an injector then start the car I bet it will flash when cranking then stop as soon as the engine starts.
First thing I would do is check the ground wire in the injector harness.
As a side note, have you checked your ignition switch under the dash?
Keep in mind 2 things:
#1 it ran before the engine swap
#2 it does not run after the swap
The possibility of something simple that is causing this is high.
That is where I would start but I'm not a mechanical expert and this is just the thoughts of an idiot that has spent hours/days trying to fix something only to find that it was a simple thing that I overlooked.
 

nepats1973

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You're stabbing in the dark. You need to do some testing before you start swapping parts/stuff trying to accidentally fix it.
I suspect you are losing power or ground to the injectors.
If you put a noid light on an injector then start the car I bet it will flash when cranking then stop as soon as the engine starts.
First thing I would do is check the ground wire in the injector harness.
As a side note, have you checked your ignition switch under the dash?
Keep in mind 2 things:
#1 it ran before the engine swap
#2 it does not run after the swap
The possibility of something simple that is causing this is high.
That is where I would start but I'm not a mechanical expert and this is just the thoughts of an idiot that has spent hours/days trying to fix something only to find that it was a simple thing that I overlooked.
I hear what you're saying. The injectors get grounded through the PCM/ECU. I Ohm checked all injector wires to PCM/ECU. Everything 1.5 Ohms or less. I tested the fuel injectors with a fuel injector test by back probing the injectors at the PCM/ECU. All injectors tested fine. Replaced the ignition switch. I have replaced many wires and Ohm checked grounds. I verified the PIP lead is pulsating from the distributor. I did accidentally reverse my battery cable leads early on after the engine swap. I had smoke before I realized what happened. After that I sent the computer off for analysis and the "guy" told me it was OK. I also replaced ALL of the fusable links. I'm really not sure what else to do.
 

jrichker

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You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix. :D

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
 

nepats1973

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I have gone through the checklist several times as I mentioned in my post. I arrive at the same point each time. A car that won't stay running. All troubleshooting points to PCU/ECM. I have no codes other than the pass code of 11.
 

7991LXnSHO

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I have gone through the checklist several times as I mentioned in my post. I arrive at the same point each time. A car that won't stay running. All troubleshooting points to PCU/ECM. I have no codes other than the pass code of 11.
Engine basics, fuel air and spark.
If it keeps running with starting fluid, that’s most likely replacing your fuel.
What is the fuel pressure when the pump first primes before starting? What happens when the engine starts? With the vac line attached to the regulator, it will vary, but if it goes to nada, I’d be checking if power stays on at the pump and relay. There are other fuel tests, but I’d start here.

Curious. How can you get through the surging idle checklist if it will not stay running? The second set of codes are with the engine running, and a cylinder balance test requires a running engine.
 

Grn92LX

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Engine needs more start up enrichment fuel, its too lean in the cold temps. Only way to fix it is with a tuning device ( chip, holley efi, megasquirt ect.)
 

nepats1973

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Engine basics, fuel air and spark.
If it keeps running with starting fluid, that’s most likely replacing your fuel.
What is the fuel pressure when the pump first primes before starting? What happens when the engine starts? With the vac line attached to the regulator, it will vary, but if it goes to nada, I’d be checking if power stays on at the pump and relay. There are other fuel tests, but I’d start here.

Curious. How can you get through the surging idle checklist if it will not stay running? The second set of codes are with the engine running, and a cylinder balance test requires a running engine.
39 lbs of fuel pressure when pump primes. only drops slightly when engine starts. Only made it to the end of first section obviously because it won't stay running. Even jumpered fuel pump to run constant which didn't affect anything.
 

nepats1973

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Engine needs more start up enrichment fuel, its too lean in the cold temps. Only way to fix it is with a tuning device ( chip, holley efi, megasquirt ect.)
I have read conflicting response to a tuning device solving my problem. I know nothing about tuning devices. How would I know which one to get?
 

7991LXnSHO

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39 lbs of fuel pressure when pump primes. only drops slightly when engine starts. Only made it to the end of first section obviously because it won't stay running. Even jumpered fuel pump to run constant which didn't affect anything.
That helps, even if those are not the easy answers.
What does a NOID light show on the injectors after fire up? I am curious if the injectors keep firing or if something shuts off the signal when you have it running on starting fluid.
(Yes, starting fluid is not the best for an engine. Neither is when you push it off a cliff for not working.)
 

Dan02gt

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Every time I've had that issue it's been timing. If you can't keep it running then you can't get the timing properly set. Try having someone start the car while you make slight adjustments to the distributor to see if you can get it to the point that it stays running.
 

7991LXnSHO

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Every time I've had that issue it's been timing. If you can't keep it running then you can't get the timing properly set. Try having someone start the car while you make slight adjustments to the distributor to see if you can get it to the point that it stays running.
Did it still run on ether with bad timing? That’s the bug in that diagnosis for me. I’ve see stuff pop, backfire and run like crap with bad timing. If it’s bad enough to not stay running at all, would it even start?
 

dgollem

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I have been following your problem hoping I could help. I usually have equally interesting problems myself. While I don't have a specific answer, I will offer the following: many years ago I remember having an old dodge with a separate ballast resistor on the coil. I had a similar problem and it ended up being wiring problem with the ignition. There were two circuits one energizing the coil while cranking the other energizing the coil while running, I don’t remember exactly how I fixed it, but it got me thinking about your car. Since your car starts on its own but dies right away but stays running on the starting fluid, I think the problem is your injectors (since you said you hotwired the full pump) lose power when the key transitions from crank to run. Ignition and timing should be close enough or it would not start. I did a search and found information see the link that may help you out. It talks somewhat about start and run circuit with a fusible link off of the ignition switch and the TFI having both a start and run circuit associated with it. While the write up does not directly address your problem it might help you anyway. Good luck.


This link describes a method to check the ignition switch.
 

Dan02gt

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Did it still run on ether with bad timing? That’s the bug in that diagnosis for me. I’ve see stuff pop, backfire and run like crap with bad timing. If it’s bad enough to not stay running at all, would it even start?
For me I killed a battery trying to get mine to stay running after doing my H/C/I swap. Start and die wash rinse and repeat. Timing was just to far off to keep it running to get it set properly. Finally my dad came over and he started the car while I made slight adjustments to the distributor. Within 5 minutes we had it dialed in and running like a champ.
 

7991LXnSHO

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For me I killed a battery trying to get mine to stay running after doing my H/C/I swap. Start and die wash rinse and repeat. Timing was just to far off to keep it running to get it set properly. Finally my dad came over and he started the car while I made slight adjustments to the distributor. Within 5 minutes we had it dialed in and running like a champ.
Checking the static timing sounds like a good idea then. Use a piston stop to find true TDC, mark it, then check the rotor to cap terminal one relationship. And I would still go after the noid lights to rule out injector signal fuel issues.
 

Krazykyle44

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Did an engine swap with my 5.0 and it ran like crap when i started up the new engine. My problem was that the spark plug wiring was set for HO and my engine was a non-HO. had to pull the distributor out, put the engine at TDC, reinstall the distributor so its on the #1 plug, then reset the timing. Engine runs like a 5.0 now :banana: Just throwing out an idea you can look into.