Hi, im new here. I have a 1994 s15, its a w code whit TBI. My car started running rich, and it uses a lot of fuel. I have changed sparks, spark wires, rotor and distrubiter. It still run rich. I tok my car to a dealer to see if he could find some codes, but nothing....
So now im a bit stuck, im getting a new temp sens for the ecm to morrow, so im hoping that will help.(Im from Norway, so my english is not so good, sorry).
I hope somebody can help.

 

Is it a W or a TBI? W is CPI, Z is TBI.

If it is running rich, it is quite possible you have a fuel leak under the intake plenum.

 

My truck does the same 89 4.3 TBI. I've replaced plugs, wires, distributor, coil, fuel filter, stat, temp sensor, ecm temp sensor, air filter, o2 sensor, cleaned the egr, couple seafoam treatments. It stinks when it runs out the tailpipe and I get about 11-14mpg. I'm not too sure what else to do either, sorry can't help. If you figure something out please post back.

 

I am having similar problems. 1990 4.3l TBI. To ensure your vehicle is actually running rich you can do a "field test" with the ECM. If you use a jumper wire and connect the A and B ports on your OBDI plug (that would be the upper right plug and the one to the left of it) with the ignition switch off, then turn the vehicle on, your service engine soon light will flash quickly about 2.5 times per second. This means that the engine is running in open loop mode, it does this while the engine is heating up. Once the engine is heated up, the light will flash slower, about once every two seconds, this is the engine running in closed loop mode. the slower it flashes the leaner its running. if it flashes a whole lot, then it is running rich. I did this and it seems my engine is running fine, no error codes are being reported, but i get a really heavy fuel smell when i get it at wide open throttle and then let off the gas. I have aslo replaced plugs wires cap and rotor, PCV valve, all vacuum hoses, charcol canister, and i am going outside right now to clean the EGR valve. hopefully we can get to the bottom of this. Happy late thanksgiving.

 

check your fuel pressure regulater. they like to leak at around 100K.

 

Hi, thx for replys guys. Iwe changed tempsensor for ecm, the car is just the same... And after the replys from u guys, i see that theres no reason for me to change o2 sensor, but i unplugged the o2 sensor when my car was hot and running, no change. That makes my wonder, shouldent there happend something??
Translated from norwegian(im not sure what its called in english) ignition modul?? Do know what i mean? its connected to the distrubitor? Could that be the reason for the fuelsmell and that the car uses a lot of fuel?
Where is the fuel pressure regulater?
Thx for the replyes.

 

Oh ya I also replaced the PCV valve. When I replaced my distribuor that was the hole thing, including the ICM.

This is from another topic.

 

The spider injectors usually break or crack after a while you may want to check those in you intake manifolds. Thats went wrong with mine a few years ago.

 

so even if the computer is entering closed loop mode, my O2 sensor could still be bad? The picture is taken directly from the chiltons manual. The way i interpret it is that if the Oxygen sensor is not outputting any voltage, or a bad voltage, then it will not enter closed loop mode. I know that books aren't always correct, so if someone knows otherwise, i will definatly give replacing the sensor a try.

 

Ludejim,
As Asimm & caddy500 have said, the most common fuel-related problem with the 4.3 cpi is the spider
fuel injector assembly and the fuel pressure regulator that is attached to it. Located under the intake plenum, it
a bit of work to get at, but if you're using fuel/running rich, theseare probably the first things to check.
Good Luck.