Engine wont start when hot!!! help!

[v8vinny]

So my friend just picked up this '91 notch. its got a fuel injected 5.0 with a 5-speed. This car at one time was a race car, that was stripped by the owner and made a street car again and then sold resold and my friend now owns it. So the motor appears stock, but you can see it has full length headers to a hack job of an exhaust, no p/s no a.c. The motor deffinetly has cam in it which seems like it might be an X-cam or something along the lines of that because its deffinetly noticeable. On top of that its got a crane cams fireball ignition. Heres the problem in the morning(or when the car is cold) it will start fine and run perfect, besides the horrible idle from the monster cam. Now once the motor is hot and you shut the car off, thats it! it will not start again untill it is cold. Ok yea my thought was the module too. So we did the basics Cap Rotor wire set plugs and module. Next day same porblem.
When the car wouldn't start i checked for spark, i checked for fuel it had everything, but it cranks like there are no plugs in the motor like it loses compression. The odd thing is though when it runs it runs strong, and we tested compression and its got perfect compression, and when it runs the timing is dead on. The motor will not fire untill it sits for at least 4 hours. Then i tried once when the problem occured, ether. It fired when the ether i used the ether and the problem was happening. So i thought ok maybe we dont have enough fuel. Changed the fuel filter, still problem is there. I NEED HELP! anyone have any ideas let me know,
Thanks alot,
Vinny

[USMC302]

Does it at least turn over. Are you pulling any codes. I had the exact same problem and when I got my PMS, I took a ton of fuel out for the warm starts and it starts everytime now. Have it turn over when it won't start and pull the plugs to look at them, let us know your observation.

[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]

Hey USMC302, what do you mean by PMS

"I had the exact same problem and when I got my PMS, I took a ton of fuel out for the warm starts and it starts everytime now. "

[Coupe50h]

vinny, the pms is a tuning device for the car's ecu, you can add or subtract fuel, timing, ect.. and at different points in the powerband.
A wonderful tool, too bad I dont have one

[v8vinny]

well i today we pulled a plug when the car wouldnt start and it was dry. I dont no now if it isnt getting fuel, but the release valve on the fuel line sprays fuel out when you push it. I'm starting to go with my the starter is getting heat soaked and i was going to try and jump it, roll and it put it in gear but no one was around to help us push. I dont no if i mention it before, but if you spray some ether in the air filter it will fire when the problem occurs.

[Coupe50h]

Assuming it has a 91 starter? like mine, it's big and unreliable, might consider getting the smaller lighter 93+ starter (more cranking torque), you just have to run an extra wire to make it work, run a search if your intrested.

[Dog5ohfun]

Check the coolant temperature sensor in the heater coolant hard line. This sensor tells the computer if the engine is hot or cold. My car did this a few years ago and this was the problem. To test this next time it doesn't start when it is warmed up, hold the gas to the floor and start the car like it is flooded. You don't have to pump the gas pedal just plant it to the floor. If it starts then it is the sensor. If it doesn't start then it is probable that the starter is worn out. But the sensor is the cheapest first solution. Hope this helps.

Brent

[USMC302]

Originally Posted by Dog5ohfun

Check the coolant temperature sensor in the heater coolant hard line. This sensor tells the computer if the engine is hot or cold. My car did this a few years ago and this was the problem. To test this next time it doesn't start when it is warmed up, hold the gas to the floor and start the car like it is flooded. You don't have to pump the gas pedal just plant it to the floor. If it starts then it is the sensor. If it doesn't start then it is probable that the starter is worn out. But the sensor is the cheapest first solution. Hope this helps.

Brent

Brent, this thread is almost 3 months old but nonetheless, holding the pedal to the floor while turning over....How does that determine a bad sensor? I was always under the impression holding the pedal to the floor while turning the engine over stops all fuel flow into the engine (meaning an overly rich condition and this would lean it out for starting)

[Dog5ohfun]

Sorry, didn't read the date. Anyway, I don't know how it worked when I removed my sensor from the car. I drove it around without the sensor plugged and one day it wouldn't start when it was warm and holding the throttle to the floor was the one thing that got it started. It worked like that for about a week until we figured out what it was and reinstalled the sensor.