Ive got a 87 5.7 TPI, I just recently replaced all the spark plugs, put on an msd cap/rotor, and a msd replacement coil. But my car still falls on its face. Ive checked the timing and it was like 12* retarded, so now thats at about 9* advanced, I was thinking it was a fuel problem but now im not so sure after reading all the stumbling/hesitating posts. It starts really easy, and sounds fine, but it hesitates a bit, and has the power of a 4 banger. Im going to jump the 5 n 6 pins to check the codes tonight, If you have any ideas please help, and thanks for any response.

 

some more info, I just found out, the previous owner just had a GM fuel pump put in back in october, so the pump isnt a year old. He also had all the plugs and wires changed. Im going to change the fuel filter here shortly, but im starting to lean towards ignition, and maybe do a compression check on all the cylinders.

 

Well I tinkered around with it last night, and I found a vacuum leak on the FPR, and another on what looks like an evap can in the front drivers side, now my car will barely idle, well I guess I'll readjust the timing, and fix the exhaust leak I found, then maybe I can get closer to the problem, and the only code that would flash was a 12.

 

The flashing 12 is not a code per say, it signals that the computer is functioning properly. Get a fuel pressure gauge and check the pressure a the schrader valve. Even though the previous owner put a new one in it might be the fuel pump, there is the possibility that he bought a low cost pump.

My 87 iroc is acting the same. I checked the fuel pressure and it was 28-30 psi. It should be somewhere in the range of 45+ psi.

Also, check the fuel filter first it could also cause poor fuel flow if it is blocked.

Hope it's not the pump if you do it the right way you're gonna spend some cash!

Good Luck.

 

could be clogged cat?

 

Well I got up friday morning and changed the fuel filter, and that made some difference, then I decided that I would re adjust the timing, that made some more improvement, then I hunted down any exhaust leaks I could find, that got rid of the annoying tick, and then I adjusted the idle, and that made a good deal of improvement, now my car is running like a raped ape. Thanks for the suggestions, and maybe this thread will help some one in the future.