I've still got my 86 T-Top GT. I have the heads back on and running/cooling beautifully EXCEPT when I restart her after 20 min or so of idling she has issues restarting. Spins over like a wild banshee so I don't think it's a starter heat soak issue.

Basically she'll restart if I hold the key for 6-8 seconds or so, if for some reason I don't hold the key that long when I try to start again while hot I get nothing.

The compression is 160-170 across all 8 cylinders. E6 Ported/big valve heads with 93 block.

I have spark and power to the injectors I cannot see the injectors toggling though when this happens, but I don't have a noid light any more so I'm just using a test light which the circuit may not be enough to light the bulb.

If I let her cool down she starts fine.

I have a new fuel pump, filter, ignition switch, coil, ignition module, pickup, distributor, starter, starter solenoid, iac, tps, cap, rotor, coolant and iat sensors (replaced them all when I redid the heads since most of the equipment was OE or old as hell )

I've tried a new PCM relay from a running car and another A9L PCM as well

I replaced most of the ground wires with upgraded wires and the EGR system has been removed.

I have an extra injector harness from a running car I'm going to try tomorrow. I'm a Fuel injection and computer guy but this is stumping me all to hell

Any ideas from some of the more seasoned Mustang guys out there?

FYI It's a MAF conversion with 24lb injectors and a Pro-Flow 24 lb MAF with a 70mm tb, cobra upper and lower intake as well....

 

sounds like heat in the fuel line maybe . causing vapor lock. u shouldnt let your car idle for 20 min like that especially not a fox body .. Just ga guess

 

Fuel line is warm but not hot when it the issue occurs unless the fuel inside is much hotter than the steel outside?

It's luke warm at best I would say. Not too hot to where I can't hold the line or anything. If I'm getting vapor lock how am I supposed to combat that? . The fuel pressure seems fine, but that could be gas pressure I guess too?

Could a non venting gas cap possibly be creating a vacuum in the tank making it vapor lock? By golly I think I have an idea to try .

 

Yet another reason for a CARB. Too many sensors on FI to figure out the problem. And you can't just flip the butterflies to see if the fuel is actually going down to the cyls like you can on a carb....So you ACTUALLY have no idea if it's getting fuel. Have you pulled a plug or two after trying this? If so, were they wet? Or dry? Pull out all the plugs and make sure they're all grounded, then twist the key. Do they all fire? Or are there some that aren't?

 

I used my timing light and clamped each wire and all were flashing correctly (old school trick ) When it happens I pull the plugs and they're dry like there's no fuel.

I really need to get a noid light and see if the injectors are toggling, I know it has fuel pressure with my pressure tester, but it could be a mix of fuel and air giving me that pressure, I'm just unsure if the computer is opening the injectors.

 

Well I had this problem on a stang just the other week. Starts right up when it was cold. After it gets hot...nothing. Noide light would not flash. I replaced the PCM and that fixed it.

But you said you already tried a PCM from another running car though right?

And NO 95cobrasvt the answer to fixing an FI car is not changing to a carb.

 

The car came with an A9T, I tried 2 A9L's I had, one came out of a running car.

 

But it would definatly cut down on the available possibilities which could cause this problem. LOL

 

try turning the key a few times and prime the fuel system. Its possible its just bleeding down or you have a leak somewhere

 

I had a similar problem on my 96 4.6. Turned out to be a bad IAC.

Hurst