94' Sub. she no run

Ok heres the skinny. It sat for 6-8 mos. We went to start it , dead battery of course, bolted in a good battery. Turns over great, no fire, no fuel. Hmmm, noticed fuel pump relay bad, replaced it. Still no fire no fuel, Hmmm, checked coil its good, checked pick-up coil its good, the book says can not check the ign. module just to try a known working one. My question is this if the ign. module is bad will the injectors still pulse or are they directly dependent on that module or am I barking up the wrong tree. I hope the ECM hasn't gone down. Anyone know for sure...... Thanks Dave

Spray in some aerosol starting fluid, see if it starts up and runs, even for a few seconds. In ALL cases like this, one must determine whether the issue is spark or fuel. The circuit for the fuel pump relay on these actually runs through the three-terminal oil pressure switch. An inexpensive spark checker tool that plugs into a spark plug wire is also a good diagnostic tool.

If the fuel pump itself is working, one should be able to hear it humming while trying to start, such as lying underneath or ear to open fuel cap. When my fuel pump went bad, banging on the tank from underneath got it going a few times.

That fuel pump - and last year I did need an ignition module - were my no-run situations over the last few years.

The Ignition Module converts the AC signal from the pickup coil to a DC signal that is used by the ECM to pulse the injectors.

The ignition module can be tested at most auto parts stores.

ECM failure is rare compared to Ignition Module failure.

//2000CAYukon

Thanks Yukon, thats what I wanted to hear. Again this has proved to be a very valuable resource for information. I will post back when I get it running. Dave

PS No Fire = spark, as in lack there of
No fuel 1st mentioned= pump not running/ injectors not pulsing, No fuel 2nd mentioned = fuel pump running fuel to throttle body / injectors not pulsing