runs about 20 seconds
 

I need some help here. My 351w runs for about 20-30 seconds than dies, and will not restart for about 5 minutes. Then it will fire and run for again for 20-30 seconds. The car was running fine about 3 weeks ago and it sat for awhile and when I went to fire it up it is running like this. During the 3 weeks span I had replaced the Edlebrock with a demon carb. So far I have rebuilt the demon carb, swapped the demon back with the edlebrock, tried a different coil, and put on a new cap and rotor. I have noticed that when I had a plug at the end of a wire that I was getting good spark until about 20 seconds and the plug was not fireing, but the engine was running a bit but really rough, and then died. I have a ford electronic distributor, I don't know if the ignitor may be bad in the stock ford electronic distributor. If you all think it may be the ignitor, what years were the electronic distributors first put in Fords as it has a small cap, not the large style caps on the 86 and up mustangs. I have a Mallory distributor I want to put in, but I would rather get it running now and then swap out the distributor, instead of playing with to many variables.
I have checked the carb and before and after and right after the engine dies I have gas squirting out the nozzles, and my pressure is 6 psi. Thanks for the help
Mike

I see your getting a lot of help!
You seemed to have eliminated or reduced the probablity of carb/gas probs.
Go with the basics. Check your ignition voltage source; ie 12V source to ign.
Check ign grounds. My experience is that most elect. problems are GROUND problems/issues.
I have been chasing a carb prob. for 3 mon. turns out it's a ign/distributor problem (I think)!!

good luck
gn

You might try installing a new magnetic pickup. You should be able to find one at your local parts store. Take the old one along with you since you don't know the year. They should be able to match it up. Good luck.

You did not mention what you are using for an "ignition box"? MSD, OEM Ford, Mallory, etc. The early OEM Ford Units were notorious for open circuits, engines dying, and leaving customers stranded. 1975-76 (First Years) was not kind to Ford as far as ignition gremlens were concerned, however they have come a long way. Be certain the coil you are using is compatible with the ignition box being used. As stated previously the magnetic pickup inside the distributor can fail, creating an open circuit when it begins to warm up, or the "Ignition Box" itself can have an electronic part fail too. Intermitent ignition problems are sometimes hard to solve.

Rick