I recently replaced the fuel pump, fuel filter, and fuel pressure regulator in my '89 5.7L IROC. The car runs great when the engine reaches 150 degrees and above, but it has some major problems starting. After turning it over for about 20 seconds, the engine finally sputters to life, but it's still really sluggish for about one minute after starting. However, I don't have any problems starting it when the engine's hot. Could it be something with the cold-start valve or injection swith?

I never had this problem before replacing the fuel system components mentioned above.

Any ideas?

 

What made you replace all those things to begin with?

 

I replaced the fuel pump because it burned out; the fuel filter because it's just prudent to do that sort of thing; and the FPR because the adjustable one that was already on my TPI fluctuated way too much. The FPR must have been a cheap one because it operated within a whole 10 psi range (and I had a high-quality guage to test it). I simply replaced it with a stock one.

 

if it's a 89 it has no cold start injector. in 89 it was eliminated and instead all 8 main injectors fire additional fuel for cold starts. you may have a problem with your injectors. have performed a tune up on the car? it could also be a failing cts or other sensor that the ecm uses for open loop operation. what the history on maintenance peformed on the car besides that already metioned?