[rfmaster]

Originally Posted by cr34t3d_by_d4rkd3n

ur saying fi?..... fuel injection? tpi or tb? tb will run safely from 5-10psi aprox, so 12 on a tb motor is high. tpi thats too weak, i dont know off hand what tpi need but its more than 12......check if its gettn spark, what the plugs are reading, also check oil, low oil pressure will signal a terminate signal to computer and not allow the engine to run.

All of the above statements related to TBI are incorrect.

1) GM TBI specified fuel pressure is between 9 and 12 PSI. Generally 15 PSI will make stock engines perform at their best - injectors provide better fuel atomization. Stock engine will idle with 6 psi, but the moment throttles are opened will stall.

2) The oil pressure switch does not 'terminate signal to computer'. Oil pressure switch is used as a fail safe device for a fuel pump relay. If Fuel Pump (FP) relay fails while engine is running the oil pressure switch contacts will provide current to the fuel pump. Oil pressure switches (NO) are designed to close when oil pressure is above 4-6 PSI. If you have bad fuel pump relay it takes a while for engine to start - about 20 to 30 seconds of cranking - oil pressure builds up and closes oil pressure switch contacts energizing fuel pump.

As to original problem - not idling in gear. Perform POST check and pull codes (if any) by jumping pins A&B of ALDL connector - see TBI thread for details. If basic checks are OK it is common on high mileage trucks to build up carbon in the IAC passage ways - this requires TB removal and cleaning. On few rare occasions IAC motor fails - when that happens amount of idle air is not controlled and engine stalls if IAC is fully closed.


//RF