Chevrolet Repair: stalling at idle 1989 chev 305 k1500, fuel pump filter, thomas woolf

Question
Hello!
I have a 1989 chev truck k1500 305 TBI that stalls from an idle. has new fuel pump/filter,tps,idle air,ecm temp sensor,O2. Truck starts and idles 20 sec or so and dies. put my OTC scan tool on it and no codes. I put in 3.7K mode(fuel backup) and it idles! tryed 10k mode idles too! truck sat for 30 days and it started it. before only sometimes putting it in gear it would stall. truck starts right back up...Runs great down the road! It has the OEM dist module? maybe loss of signal from the module at low rpm?
I do hear the rush of air in the TBI as it stalls.
any data you need from the OTC 2000 scan tool i can give you! only thing i am not sure of if its a open or closed loop thing? i will check that tomorrow..I think its both...I changed the temp sensor because it was going to closed at 120F...Is the O2 what tells it to go into closed when the O2 gets around 500-600 deg? I was keeping the idle up  at 1200 rpm from cold start.

Thank you for any help you may have!

Thomas woolf in N.C

Answer
CLOSED LOOP is obtained when the o2 sensor heats up and starts sending varying low voltage signals to the ecm.

There are numerous possibilities from  loose or corroded electrical connections to heat sensitive components.

I have seen heat sensitive dist modules and pickup coils to loose ground wires where previous work had been performed.

Without having physical access to the vehicle and runninmg my own tests it is impossible to make an accurate diagnosis.


autohelop