Hey guys got a blazer Tahoe with the TBI 4.3 that has an idle surge and stalls in park or when coming to a stop. I have been all over s10 forums and online and here and it seems to be pretty known about it happening but I cant find resolution to my problem.
I bought it from a customer at work where I replaced the;
Distributor, cap, rotor, wires, plugs, fuel filter, PCM, fuel pump, ECT, IAC, TPS, MAP, EGR valve and cleaned the throttle body and preformed a carbon service.
After all that I thought it would be a safe purchase. It ran great for 2 weeks and its back to stalling. Seems to be getting worse. Seems more likely when hot.
Since the idle drops out/surges slightly in park could it be the injectors cutting out? maybe a weak coil? I didn't find any vacuum leaks and I run premium fuel. The timing is not retarded or advanced.

Thank you guys!

 

Also the fuel pump has the updated connector and when I disconnect the electronic ignition advance (brown wire under passenger side floor board) it runs fine.

 

Well I found that the previous owner installed an after market oil pressure gauge and completely messed up the threaded connector that connects the sending unit to the intake.
I have special ordered one from chevy and now I play the waiting game... The fuel pump wasn't seeing oil pressure and I think that was causing it to stall out.

I am also gonna double check the grounds. If anyone has input on the grounds please let me know. Ill update when I get the sending unit connected next week.

 

Have you checked the fuel pressure, TBI needs 9-11 psi.

 

Last time I checked (a few months ago) it was 9psi.

 

installed oil pressure sending unit and its still stalling. Also factory oil gauge falls to 0 psi at idle. Old gauge read pretty low but never went to 0. No valve noise or knock. Just burns a little oil on start. Maybe a bad computer?

 

Still no fix. Been driving around with wire disconnected. More testing soon

 

check the throttle shaft for play

 

Throttle shaft?? what do you mean?

 

it's tbi, the shaft the throttle blade is attached to (the one that moves when you hit the throttle) has bushings that when they go bad create a vacuum leak, there shouldnt be any play in the shaft, it should be solid. Also see if the fuel spray from the injectors are a nice cone spray with no solid lines of fuel