Originally Posted by wtrskick
I have replied on this thread before about the issues Iím having with my 97 Prostar with the LT1. I thought I would recap what I have tried. My hard starting issue would occur when the engine was shut off after skiing and getting engine warmed up. We let it idle several minutes at the dock before shutting it off and the temperature wasnít running above normal, (180) on the gauge. If the boat sat for around 15-30 minutes it would start, but act as if was a carbureted engine flooding out. So after reading this thread I tried a new IACV valve and did the procedures to reset it. Now when it starts, it idles at about 1000 to 1200 rpm and runs rich (black smoke out of the exhaust) and the check engine lite is on and will not clear, even after the battery is disconnected for several minutes. I replaced the IACV with the old one and the issues are the same. I tried to find a code reader that would connect to the ecm plug but havenít had any luck finding one that has the right connecting plug. My next move is to take it to a dealer (200 miles away) unless someone has some insight on what I can try.
If you have black smoke AND high idle, I can't see a way that it wouldn't throw a code. Do the paper clip code scan (DLC terminals A and B)- plug the paper clip in before turning the key to ON and once the key has been turned, watch for anything other than 1, pause, 2 (designates 12) and see what shows up. If it comes up with 14 and/or 15, the ECT is bad, the terminals are corroded/damaged or the wiring has problems.
Did you replace your TPS? If so, was it specifically an LT-1 part? This is important- if the usual TPS is used, it can be hard to start with the throttle closed and it won't run right because the LT-1 TPS is reversed- the normal one will show WOT when the throttle is closed.