Hey guys I really need your help. I swapped my 305 for a nice 350. I have added Hooker shorty headers Cop Car TBI and Chip from same car. Yesterday I put a new pump in tank and a new knock sensor for the 350, but when I crank the car it runs 5 seconds then dies. It will crank right back up and run 5 more. Please I have tried everything I have read on here. The first time I cranked it it ran about 5 minutes I ran it through the gears while sitting on jack stands, next time I tried it it started this.

has it backfire or spudder in any way. seems to me it sounds like a defective fuel pump.

No backfire or sputter idols fine and sounds good haven't hooked up the exhaust yet.

I dropped the tank, fuel pump rubber line had a hole in it. I replaced the pump and hose, put it back in car cranks and idols fine. Putting it back together to see how it runs. Thanks

Sounds like its only getting a small squirt of fuel at the beginning and thats it. Get someone to crank it while you watch the injecters and see if there is anything odd (like the injecters stop pulsing).