Fuel/ECM Problem

[yourshadow24]

1993 Chevy S-10 4.3 TBI. i have a problem with my truck. i went to start it and let it warm up yesterday for about 10 minutes, as i walked out the door to get in my truck it suddenly died. when i went to start it again i had nothing . i've tested the spark, fuel pump, and fuses all where fine. when i went to test the injector harness with a speciality test light i had nothing which tells me a computer problem. is there anything else anyone can think of as to what this might be and if not how hard is it to replace the ECM? one interesting side note is the fuel pump primes when the key is turned to the ON position but does nothing when cranking.

[Blue Bowtie]

If the fuel pump primes, the ECM is obviously powering the pump relay. Make sure the ECM is getting distributor reference pulses, and that the injectors have power (the ECM only completes the ground side of the circuit to operate the injectors).

[DelCoch]

Originally Posted by yourshadow24

one interesting side note is the fuel pump primes when the key is turned to the ON position but does nothing when cranking.

I don't know about the '93, but on the newer models the fuel pump only runs for 2-seconds when the key is turned on and then the key has to be off for ten seconds before the pump will run for another 2-seconds. Thus, in a no-start the fuel pump doesn't run while cranking the engine.

Where did you test for spark - at the coil or each spark plug? As a general rule the computers don't fail that often.

[old_master]

Any time that the starter is operating, the PCM should energize the fuel pump relay and the pump should run. Any time that the PCM detects that the engine is not running after 2 seconds while the key is in the "ON" position, the PCM shuts off the fuel pump relay.

[MT-2500]

Originally Posted by yourshadow24

1993 Chevy S-10 4.3 TBI. i have a problem with my truck. i went to start it and let it warm up yesterday for about 10 minutes, as i walked out the door to get in my truck it suddenly died. when i went to start it again i had nothing . i've tested the spark, fuel pump, and fuses all where fine. when i went to test the injector harness with a speciality test light i had nothing which tells me a computer problem. is there anything else anyone can think of as to what this might be and if not how hard is it to replace the ECM? one interesting side note is the fuel pump primes when the key is turned to the ON position but does nothing when cranking.

To get injector pulse you will need ign pulse/spark.
Check for good spark to all plugs.
If no spark to all plugs check ign module.
Remove dist cap and check for dist turning.

[lkijawski]

My son has a 2003 Sonoma 4.3 with a fuel pump problem. It intermittently works, we replaced it and it is still doing the same thing. The pump doesn't run when you turn the key on. It's not getting power at the pump, we swapped the fuel pump relay. That didn't fix it. Any suggestions?

[MT-2500]

Originally Posted by lkijawski

My son has a 2003 Sonoma 4.3 with a fuel pump problem. It intermittently works, we replaced it and it is still doing the same thing. The pump doesn't run when you turn the key on. It's not getting power at the pump, we swapped the fuel pump relay. That didn't fix it. Any suggestions?

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MT