I swapped my 305 for a 350 and built it up with a mild to strong cam and lifters. I bought a 91 tpi system (computer and all) off a 91 305 z28. I installed it and added an adjustable fuel pressure regulator along with a after market prom. The problem is that it starts and runs but runs poorly. Smokes black smoke and unstable idle. I don't have a smog pump and I have added headers and
some other typical upgrades but would like some help. I also noted that all sensors work, vacuum is only 13psi, fuel pressure is 40psi, and fuel to air ratio gauge is not
saying to rich. Last is if anyone can give me a accurate pin out for the 91 305 tpi ecm. Thanks everyone!
THIS WAS A WINTER PROJECT THAT NOW TAKING ALL SUMMER!

 

I can tell you from experience that your car will run better with the smog pump. Do you have cats on the car? Also the 350 TPI like my 91 Z-28 has, from the factory has 22lb injectors with the fuel pressure reg. at 42lb. TPIS recommends 46lbs for slight improvement in performance and still ok economy, and 50lbs at the regulator for peak performance if you dont mind the gas mileage decrease. The stock 305 TPI has 19lb injectors at 40lbs to regulator. I would use the injectors out of a 350 TPI car and an adjustable fuel pressure regulator from BBK. Using the 350's fuel combo in conjunction with a working smog pump and cats should clear up the problem and give you better performance.