ya i wish it was just the fuel filter...the new carb came with new filter already installed..and theres no inline filter cept the one i put in by the carb its more like a glass prescreen, plus the sock filter in the tank i already checked out which is good. to add to that i installed a fuel pressure gauge and that flutters at and around 7 to 10 psi ...cam sensor and egr are all thats left that i havent looked in to.

 

I would really start looking into the MAP sensor troubles. I have posted the proper resistance values for various altitudes in a few other posts and GM MAP sensors should all have similar base values. It's something to start on. The MAP sensor is pretty important on the early engines.

 

MAP sensor on a carb? I didn't know such a thing existed.

 

Fuel delivery problems on carb vehicles are expressed much like non-computer cars back in the old days; Let it idle, the carb bowl will slowly "fill". After idle for a few min, full power can be obtained for a few seconds until the bowl runs out. Even in a computer carb 85 model, if it's pump/line/filter/needle valve, it should follow those characteristics.

I read the beginning of this thread and I THINK we are talking about a computer controlled carb, right? A solenoid clicks the primary needles open and closed continuously? If that's the case, yes, you should verify the MAPS but also the "Coolant Temp Sensor".

Keep in mind that even the early systems had two modes, "open loop" for when the car is cold and it can't trust the O2 sensor and "closed loop" for when it warms up and does trust it's feed back.

If the Coolant Temp Sensor" is broke, it will tell the computer your car is very very cold. The computer will then richen the mixture up. When you motor really is cold, it might run OK, but when it warms up and the computer is still dousing it with too much fuel, it would run poor and pump black smoke.

Good Luck