QuestionHello,
I have a 1990 Silverado 1500 Z-71, it had a stalling issue occassionally when you came to a stop at a light, last week it stalled, and would not restart. I changed the fuel filter, saw no fuel coming out of injectors when trying to start. I detached the gasline at the throttle body and tried to start engine, no fuel came out which prompted me to change the fuel pump. Still not starting but pressure seems great at throttle body. I checked injectors for voltage, showed current on one side of each of the two injector electrical connectors, yet no fuel sprays from the injectors to start the vehicle. It has a TBI injector system. What next? Pressure regulator? ECM? Any ideas would be appreciated. Thank you, Larry
AnswerHello Larry,
You are doing everything right so far.
Would be nice to have a pressure tester to be sure, but the pressure is a little hard to test on a throttle body. There is an adapter that goes into the place of the filter, and there are some kits to test it at the throttle body.
But the pressure should be 12 to 14 PSI.
I have seen them run at 7 PSI, but ran terribly.
But if you think you have ample PSI, the next test is "Noid" lights. They connect to the injector connectors, and show if there are pulses in the injector power.
A test light should also work. With the engine cranking over, the light should blink dimmer.
I assume you have made sure there is spark, and have probably primed the engine with some gas down the throttle body, to see if it hits on that gas.
The ECM pulses the injectors, but in order to do so, needs a signal from the crank sensor, which I believe on yours is in the distributor.
The fuel pump relay also needs that crank signal in order to continue operating the fuel pump longer than 2 seconds.
Check the fuses, especially one marked crank.
Don't just assume the crank sensor is good though if the fuel pump continues to run, because there is an oil pressure switch that powers the fuel pump directly, once oil pressure exceeds 4 PSI.
Van
