Car Only Runs When Starter Is Engaged

Gary Stanton

New Member
Aug 13, 2013
I just did a 5.0 manual swap on my 1993 4-cylinder automatic lx mustang. I bout a 1993 5.0 wiring harness and a A9L computer. I have everything hooked up and when I start it as soon as I let the key switch back into the run position it dies. Any ideas on how to fix this problem?
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It's starts first hit and sounds good but it won't stay running unless the starter is kicking in I've checked the solenoid and the coil they are fine the battery is good to and when I did the swap I didn't get the harness for the t5 manual I just spliced the two wires together so it would start with the key.
It still sounds like either an ignition switch problem or a wiring problem.

Let's holler out to @jrichker . He's our resident wiring guru and probably has a simplified schematic and troubleshooting tips lying around that can help you.
I just turned the key to the run position and bumped it with the screw driver but it did the same runs and idles just fine long as long as the starters turning but I took the screw driver off and it dies
Look to ensure the wiring to your starter solenoid is correct.


From the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs"

Paragraph 1, item K....

K.) 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/blue 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. No 12 volts, replace the ignition switch or the fuse link in the red/green wire.

Notice the fuse link in the ignition circuit below...
Diagram courtesy of Tmoss & Stang&2birds


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Everyone should bookmark this site.
Ok new problem with my 5.0 it starts fine and idles ok but when I get in the the gas it spits ,sputters and backfires. And when I drive and barley give it has it's fine but if I get on it , it's like I'm riding a bull.any ideas ?
I had the wires on the solenoid backwards(:cautious:)


I mean... uhermmm... was that so hard? :D

Ok... next problem. Check your timing with a light first. Should be set to around 12*.
Pull KOER codes. If no codes go to next.
If that checks out, just swap the TPS sensor. Yes... you can check it with a DVM but they're so cheap, it's just as easy to swap it out.