OK I have a 1989 Chevy blazer 4.3L 4x4 I have recently bought. I've been having some fuel related issues I believe. It seems to be flooding itself out almost while running at idle after I drive it for a bit. Also gets horrible MPG. I originally thought it was a misfire so did plugs, wires, cap, and rotor. This didn't fase it so I changed distributer and compression tested all cylinders and used a bore scope to check for any damage to bore hole or piston head. Any ideas what else it could be. Only thing I can think is injectors or the TB itself. MIL is intermittent and shows no DTCs even when it is on.

 

Ok nobody has posted anything in 40 ppl reading this.
Personally I'm not familiar (can't remember my engines from that era) but a Search in here for the issues will probably lead you in the right direction &/or give you more Search ideas.

 

If it runs ok on a cold start for a couple of minutes, it may be caused by a lazy or dead oxygen sensor. On a cold start up, the ECM ignores the oxygen sensor, when it switches to closed loop, it uses the oxygen sensor to monitor fuel mixture. If the sensor is lazy or dead, it will report a lean mixture which causes the ECM to richen the fuel mixture. If it runs poorly all the time, there may be a problem with the ECT, (engine coolant temperature) sensor reporting too cold, again, this will cause the ECM to richen the fuel mixture. There are 2 ECT sensors on your 89 engine: the one in the driver side cylinder head is for the dash gauge. The one in the intake manifold is for the ECM, that's the one that may be faulty.

 

I would check the coolant temperature sensor. A bad CTS can tell the computer that your engine is running very cold and make it run very rich. Note that I'm talking about the *sensor*, not the sender. The sender is in the passenger side cylinder head and just gives a signal to the dash gauge. The computer actually reads the resistance on the sensor to determine how much fuel to inject.

 

Ya I was messing with it last night some thinking it might have been a IAC or TPS issue and noticed after I busted the IAC that the temp sensor is corroded and there are a few grounds on the intake that are corroded as well ... probably replace grounds and temp sensor tonight and see what happens.

 

And y would the ECM. thinking the engine is cold turn. On the mill but set no codes

 

Its on the passenger side on the old early 4.3 tbi

If the coolant temp switch is bad,the computer just thinks the engines cold,and it'll dump more fuel. At least thats the way its always been in my experience on these.

Replace the switch beside the top rad hose and clean up the plugs and see if it helps.

 

Thinking about replacing my CTS on the jimmy, just because i do not know the last time it was done, and its only 10 bucks for the part, looking for anything to improve the mileage LOL

 

what are you getting on yours? My dad gets 21 mpg on his cpi with tools in the back. He does indeed drive like the 100 year old in front of you that pisses you off.

 

So I changed the CTS and put new ring terminals on the intake grounds. It does seem to run better but still " Chugs " pretty bad at low speeds and low RPMs. I finally got it to give me the flash codes and got a 22 which if I remember is a TPS low voltage and a 43 which I believe is for the ESC. circuit ? Anyone know if those are infact what the codes are and if so any idea where to start with repairs?