I have a 1993, 2wd, 5.7l, and it used to run great. As of two years ago, it started killing the battery. I found the short and fixed it, parked it because we drove the suv more with the kids, and I left it for about a year. Threw a new battery in it and tried to start it, nothing. Pulled/pushed it into my garage and determined that i was getting spark but no gas. Bypassed the fuel pump and it worked. I am getting the usual amount of resistance across my injectors. And my fuel relay works when it gets power, which it is not. I just switched out ecm's and still no fuel. Thoughts?

 

“Bypassed the fuel pump and it worked.” - assuming you mean you bypassed fuel pump relay and it started. Or you put fuel down the TBI and it started.?
assuming you bypassed relay and it started it sounds like ICM or wiring to/from. ECM needs ref pulse from icm to turn on fuel pump. I think you get baseline spark without icm talking to ECM. ECM just advances/retards timing.
I’ve never debugged an icm but a lot of threads on ICM debug

 

Yes, please explain "bypassed fuel pump"

 

I bypass the fuel pump relay by connecting the gr/blk wire coming out of the ecm by connecting to the white power in wire. Given, this way has the fuel pump running when the key is in the Run position. But it allows me to push gas up to the tbi.
i did the 9v battery test on both the injectors, both had beautiful and uniform spray patterns. So if i van figure out the injector problem, i can get it running.
so how would I go about finding and troubleshooting the ICM?

 

So you are saying you can get the fuel pump to run but injectors don't fire? When my 93 Sub has done this,changing the ICM fixes it every time.(on 3rd one)

 

What does the ICM look like/where is it located? Ive found something ontop of the block, but it doesn't seem to have the right number/types of connectors as the ICMs I can find for sell. I also cant find an Ignition Control Module in the wiring diagram.

 

ICM is in distributor. Just search ICM in the forums or google. playtbi posted the schematic in your same thread in https://www.gmtruckclub.com/threads/.../#post-3298448

 

Not too expensive and quick easy change. Make sure you use the heat paste on installation; should come with new part.

 

Ok. New ICM. New Oil pressure switch.
The fuel pump does not come on by its self. (Bypassed by connecting gr/blk wire [computer to relay] to white wire [ignition hot] at plugs on ecm)
The injectors are not firing. (Conducted 9V test, and both work. Both are 0.02 ohms above book suggested tolerance [they have always read that way])
I checked the timing and spark, both are good. (White spark) (had to redo timing because my toddler was with me while i replaced the oil pressure switch)
If i pour gas into it, it will fire off.
Thoughts?

 

always a bummer when you replace what you think is the problem and still have the problem
Does it run with the fuel pump relay jumped? or only when you pour gas down the TBI?
btw - memory is you can jump the relay at the relay, you should be able to find a relay terminal pin out online somewhere. also - the ALDL has a pin which when you put 12V will turn on the fuel pump relay. It's a pain to get into the ECM and can be risky jumping stuff @ ECM as if you get it wrong it could hurt something. I'd figure out how to jump it at relay.

If it only starts when you pour fuel down the TBI - then two possibilities
- you are confusing not enough fuel @ injectors with the relay not energizing and in reality the relay is working and the pump is not delivering enough pressure
- you have both too low fuel pressure + something else preventing the relay from energizing

If it starts, runs with the fuel pump relay jumped, you have at least enough fuel pressure to get it started and problem is somewhere between ECM, relay, ICM
If it runs with relay jumped - the pickup coil is delivering enough to ICM to let it fire the spark and question is why the ECM is not energizing the relay. It would seem that has to be a connector, wiring to from sort of problem. I've not debugged something like that but have seen threads in past on this. Probably can search on ICM in forums and find a previous thread on same question.

either way - good practice on something which has sat is to check fuel pressure. here's a good link on that https://www.chevytalk.org/fusionbb/s...php?tid/253427