I have a 85 fb with a 12a inside it got RB headers, RB intake and holley carb. It was running alright with some studder, but it ran. It would shut off some times while driving and it took a couple of minutes to get it going again. I was driving home on the highway and it suddenly died. Tried to start it but it starts for a few seconds then shuts off. I have also had it floored and it revs up but still shuts off. It has fuel and spark. Changed everything except for the oil. Gas in filter is an redish color. Tried doing a deflood with the fuel pump off but no help. Also cant roll up windows unless care is on. Could it be the ignition switch. Does any one have any clues.

 

Could be the electrical or the motor or a combination of the two. Take a volt meter and checking the power from the alt and see if there is electricity to the fuel pump. you may have a bad connection in the dash or the starter. if the engine acts normal while it runs then you should look toward the electrical. check everything fuel related( filter etc) that stuff will go bad eventually. If the motor feels funny or weak pull the header off and look in the exhaust ports at the apex seals. If they are cracked, nicked, etc. you may need to rebiuld the motor. Good thing is that you may have dodged a bullet if that is the case. But alot of motors have been going lately. I guess an original 12a can last for only so long before it pops.