I just recently un seized this 1990
​​​k2500 that has been siting for over 10 years and the first time I tryed to start it, it had very weak spark, couldn't even run off the starter motor. It has this for about 20 seconds and then, nothing. So I replaced the distributor, and coil. Still nothing. The coil had power and the ICM seems to have power but still nothing. There is no fuel pump as well as no turn signals. The 2 wires between the ICM and coil are good I tested them but I'm not sure how to test the other connector on the ICM. I'm stumped at what it could be. I've been chasing it for a month and have no clue what it could be, I've read countless forums and tryed their suggestions but I can't seem to get even one spark out of it. Any ideas what could have died in those 20 seconds it worked?

 

After sitting for 10 years, one of the first things I would check is behind the glove box where the ECM is located. Mice love nesting in this area.

​​​​​The ECM needs a crankshaft signal to properly time spark. On initial cranking, it will command spark once or twice, but if it doesn’t receive a crank signal, it will disable spark.

You can try disconnecting the spark output control circuit (single wire connection at the firewall) and see if it produces steady spark.

Is the battery new? Fresh gas?

What all have you done so far besides the distributor and coil?

 

I did disconnect that wire and it made no difference. The wires leading to the ECM seem fine and there are no mice back there
The battery was new and I've just been using starting fluid to try to get it to fire. There is about 5 gallons to fresh gas in the tank but it's probably evaporated due to the lack of a gas cap. The only new parts I put in were the distributor, and coil and a starter. I've checked the fuses multiple times and the are currently all fine but after I cranked it when it was partially working the injector fuse did blow.

 

Pour some fuel in the throttle body, see if it fires

 

I did and still nothing. I have no clue why it refuses to have spark

 

Oh yeah I just remembered I also did put all new spark plugs in too.

 

New ICM?

 

I've tried 3 over the past 2 distributors and nothing. I think it's a really hidden wiring issue

 

Verify if it’s getting a signal from the crankshaft sensor.

Backprobe the signal wire at the sensor and monitor the voltage while cranking. It will be easier if your meter has a min-max recording function, but you should see the signal switching back and forth between battery voltage and near zero as the engine is cranking.

If it’s present at the sensor, back probe the signal wire at the ECM and recheck. If it’s not there, an open or high resistance on the signal wire is likely.

 

Sorry I was gone all last week and had a ton to catch up on so I didn't have time to mess with it. If I'm understanding this right, then the pickup coil is working if that's what the crankshaft sensor is. I think it may be the ecm so I will try to track down a good used one from another similar truck. And how do I tell that wires go where because they all just go into a bundle behind the engine and I can't follow them.