92 s10 blazer 4.3 starting issues

[chevymotocross]

My father's 92 s10 blazer with the TBI 4.3 has had a wierd starting/idle issue since we bought it. It won't start cold unless throttle is applied. It will then start but idle low. Once warmed up, it idles decent but usually throttle will still have to be applied to start it.

Here is what we have done: Fuel pressure checks out fine at 13 psi. Fuel pressure regulator and fuel filter have been replaced. TPS voltage checks have been done. Checked for vacuum leaks.

What else could be causing this? IAC? What is the procedure to check or reset the IAC?

[nightmare]

my father's 91 blazer started doing this a while back too. we checked/replaced every sensor that we could think of. when it was warm, it would work fine, but only on a cold start would this happen. when all of our ideas didn't work, we took it to a reputable repair shop close to the house. they ran all sorts of tests and tried a new computer, but that didn't help. when they came up with the same results, they concluded was that there wasn't any communications between the computer and the sensors.

what we are going to do is try to find a 6 cylinder HEI dizzy and a 2 barrel carb that aren't computer controlled. this should fix the problem for good.

as far as the IAC, the only thing that I know to do would be to reset the computer. should reset everything else too.

[Damien]

The IAC could be dirty or worn out. Take it off and inspect it. Look for carbon and wear.
The last time you asked I suggested it might be the coolant temp sender. This is a very common thing to fail on a TBI engine. It tells the computer what the engine temp is and if bad will make the truck run very rich and the throttle will need to be held wide open for the engine to start. If you have access to a scan tool, check the coolant temp with the engine cold and compare it to the ambient temp.

The IAC is more likely the problem on the CPI engines. You could also have bad or dirty grounds. How are the plugs, wires, cap, rotor?

Performance Distributors makes a HEI for the 4.3. A little pricy though.
http://www.performancedistributors.com/gmssdui.htm
I found a large cap computer controlled HEI for a 4.3 then changed the pickup and module to the old style 4 pin non computer controlled. I think you could do it with a v8 dist. too, but the star wheel and pickup would have to be changed to the V6 parts.