My wife was driving and the blazer died i came out sprayed with starting fluid, vehicle started and died. I figured that it would be fuel pump, towed home, pulled old pump, installed new pump with new harness. I tried to start it and it would not start. I'm not getting spark from the coil, i rechecked my work to make sure i wired the pump harness correct and have checked everything i know to check. I have went through the schematic that Lesmyer provided on one of the other threads. I can unplug the icm and make the coil fire by using a jumper from battery ground to the white/black wire on the icm plug with the key on. I also noticed my instrument guages are not working properly, speedometer is reading 100mph and the only other gauge that seems to work is the battery charge gauge. I have 3 of this style blazer and have swapped parts just to verify that my findings are correct, coil is good, icm good, crankshaft sensor. I'm hoping one of you guys can get me back on track, what am i overlooking? ECM? Thanks in advance several of you have already been a great help with prior post on other threads.

 

I'm sure that I'm doing something wrong on this site and my vehicle. If I'm doing something wrong please let me know. I have no intent to cause problems. I'm just an old timer that is as lost on a computer as i am on this blazer at the moment. I recognized that i have already made at least one mistake by posting questions in the new member area, thankfully someone caught it before everyone saw that I inadvertently did not read the rules and regulations properly! Thanks and sorry for any issues i might be causing.

 

Wow, that sound frustrating!

You were able to get it to run briefly with starter fluid but not again. At least at that time you had spark but likely no fuel.

With sudden failures, I always think of something electrical. Although I'm guessing you know that can be only good guidance, not a hard-and-fast rule.

Can we assume it is still cranking but just no start?

All right, as my father taught me; To run we need fuel and spark.

For the fuel, have you confirmed that there is fuel being delivered or the system is pressurized by the new pump?

Is it possible there is some issue with air in the fuel lines from when you replaced the fuel pump? I'm not familiar with that system so I only ask so as to exclude possibilities.

As for the spark, have you checked if you are getting spark to the spark plugs? I've done this by using an inductive pick-up timing light on one of the spark-plug wires. That would confirm if the ignition system is working all the way to the plugs. The ultimate test of course is to also use an adjustable gap tester to measure the distance over which the spark could jump.

If the above spark test test fails, perhaps there is an issue with your distributor. I can imagine situations in which something is failing in a way that it is digital (on or off); i.e. alternating between working and not-working before a complete failure. A bad rotor maybe? (Bear with me as I'm reaching for straws here! LOL)

With the gauges acting funny also, that means there is likely something in the control circuitry to consider.

As I also learned from my father, even it if it is unlikely, go ahead and try the easy solutions too just in case that is the problem. With that in mind, have you checked all of the fuses; both in the passenger compartment and under the hood?

You are fortunate to have other Blazers from which you can get parts to swap. To test each component, I would suggest (if you haven't already done so) to test the suspect part on one of the running Blazers. If you only tested a part by installing it on the non-running Blazer you could get a false-negative if there is more than one thing wrong.

Good luck,

Christine

 

Using a test light powered with 12V, probe the wire at the ICM (connector disconnected) that goes back to the ECM. If it doesn't flash when cranking, then the ECM is not completing the circuit for the coil for whatever reason. This is a little more definitive than making the coil fire (which is a good thing to know) but tests the ignition in a different way. Try that and let us know. If the light flashes, then crank sensor and PCM are OK. If it doesn't flash, use a scanner to verify crank sensor pulses are being read and understood by the PCM, by seeing an RPM on the scanner while cranking.

BTW this post (now) appears where it should in the 2nd gen tech - so there is no problem with your posts