hello..i asked last week for your guy's help...the 91 305 Rs tbi was running very rich...then would not even start...it had spark,fuel,comp....turns out it was the plugs were all fouled...i put new ones in and it fired right up...i thought it was running rich befor because of a bad o2 sensor...so i got a new one in......so this is my new question?,....it is still running very rich...black smoke out the whole driveway...i had a 1/8 a tank of gas...and just befor it ran out...it leaned out ran greatfor a sec .. and dyed...so i poured 5 gals. in...it starts and runes very rich...so why dont the computer read that it's so dam rich and start the lean?...not sure on the closed loop stuff so i let it run till hot...still bad...i unhooked the batery to reset...still rich....sooo does anyone have a idea whats going on?....

 

The coolant temperature sensor is probably telling it that the engine is -40°F.
It's a different one than the one that works the gauge.
If it never sees the engine warm up, it never goes into closed loop and ignores the O² sensor.

 

ok...which cts feeds the computor...i see there is two

 

The one that is in the passenger side head, is the one that...Well I guess it tells the fans to turn on, I thoaght I was 100% until I started typing. The driver side sensor is for the gauge right? Pass. side is for the fans right? So which one does the computer see?

 

CTS that feeds the ECM should have a yellow wire and a black wire at the connector.
Have you pulled the codes?
This may not be the problem.
Is the SES light working? Is it coming on when the car runs?
A bad TPS or a bad MAP or a stopped up CAT can also cause this problem.
Fetch the error codes and holler back. Parts stores will do it for free.

 

update..no cat..strait pipe with a flow master out back...ses works...on key-up thats it...does not come on when running rich...no codes....anyway i remembered i have a complete 4.3 same year...so i swaped the cts with it...both the same...car started...and right away started running better...and after getting all the built-up fuel out of the system...it started running pretty good!!...but before i can roadtest i need to swap a water pump...mine is leaking from the weep hole...so i will let it cool and swap out...then go for a ride tomorrow...it's getting dark/late...i'll let you guys know... thanks!!

 

Thanks Super42...runs great...it was the..CTS ..( coolant temp sending unit) computor one

 

You're welcome! And thanks for posting back so future searchers will know this solved the problem.