Engine wont start when hot!!! help!

[meknized]

Hey, I think I MIGHT know what the problem is. My dad has an '87 Cougar XR-7 that has had the '89 5.0 HO swap, ported heads, cobra intake, exhaust etc etc etc. He had the exact same problem, after it became hot it wouldn't start and would barely crank. Like you after it was cold it would fire right up. I spent probably two hours trying to figure it out and like you it had spark, fuel, everything. One thing I did notice was that the spark was actually a yellow not a blue even though it has full MSD ignition. Well, to make the story short(er) The ground strap from the firewall to the back of the head was totally loose, plus my dad had grounded the negative battery cable to the inner fender instead of the block. I tightened the firewall ground and moved the battery cable to the block and BOOM it fired right up and hasn't had that problem since. It even seemed to have more power. Check the grounds, look for corrosion, tighten everything down and make sure all ground straps are there. Let me know if that was it. Good luck!

[bmxmon]

His starter could also be heat soaked from the headers, happened with my mustang (65).

[USMC302]

Originally Posted by bmxmon

His starter could also be heat soaked from the headers, happened with my mustang (65).

Exactly my thoughts as well, which my first question was about it turning over...

[93svt]

I had a similar problem with my Cobra, sounds silly, but it was actually too much initial timing, 21 degrees. It smelled flooded. When it didn't start I tried flooring it because supposedly it is supposed to stop delivering fuel with full throttle when cranking, but that didn't work, so I tripped the inertia switch and then it could clean out and start. I guess try that. It did this consistently on warmer days until I figured it out, don't know why anyone would put that much timing in, but I put it to 14 initial, and no problems since. Also could maybe be weak fuel pump. Good luck.

[v8vinny]

ok the car does crank over when the problem occurs, but it cranks almost like the plugs were pulled out. Im going to check if the plugs are wet when the problem occurs. But the timing i no is at 12 degrees i set it when the car was running with the plug out i no it's right. So my next step is im going to try pulling a plug and im going to see if i can get a scan tool and try to pull some codes.
Thanks for the help so far

[USMC302]

Any new news?

[v8vinny]

I looked all over the car and it had no engine ground. But it also has the battery mounted in the trunk so the negative cable cant be grounded to the block, but it is grounded to the rear frame section. We added a motor to firewall and motor to k-member ground, and you guessed it still same problem. I havent been near the car in a few days I've been sick, but my next step is to pull a plug when its hot and see how they look. I havent had time to sneak my scan tool out of work to go check it for him either, and i cant go by the check engine light being on because i dont think it works, becasue the o2 sensors are not attached and there is no light.