OK i got a 89 Trans Am 305 TBI that wont start and if it does start the rpm jump up and down and then it stalls. I checked for vacuum leaks and replaced wires, spark plugs, and cap and rotor. I also changed the fuel filter which was clean anyway and changed the fuel pump. I still get the same results. Did i miss something? And does anyone know the fuel pump circuit wiring? I have a yellow wire hanging in my fuse box and i dont know what it goes to could that be it?

 

i think you need to try trouble shooting instead of random parts replacement. does it have spark? does it have fuel? does it have compression? if or when you can answer yes to those 3 questions you're 99% there. if you answered yes i'd check timing, codes, fuel pressure and volumn. WAG i'd say the yellow wire in the fuse box goes to a amp or cd player, something added on later. if you never did anything there's not much chance the wire came disconnected.

 

Never mind. I found out it was the fuel pressure regulator.