When I first start Blazer,it runs great until it reaches operating temp,it starts to misfire and when I increase throttle it will die.I have replaced spider injection,new distributor,coil,plugs,wires,and set timing.Blazer is Vin W.Also,when I have my timing light hooked up,it flashes normally when cold but when it warms up,it begins to flash intermittently,stalls,backfires and eventually dies. When it cools it will start and run until warm and then stalls and dies.What would the problem be?

 

Things to check - Vacuum leak, check your Upper intake gaskets since you said you replaced the spider, actually, especially since you replaced the spider, check your intake duct work and make sure its all tight, any leaks past the MAF - if it even has one, not sure on a '93 - will cause issues. check your vacuum lines and if needbe cap them off using a screw and the right sized nub of line. check the quality of spark, iirc your vehicle is pre OBD-II and maybe even pre OBD-I, not sure on that.

 

If ignition is letting out when warming up it may be the ignition control module. We have seen them go out this way. When cold it's fine, it may even run when warm but not re-start and when cool it starts again. An indicator being your ignition missing.

 

I thought the ignition control module would be starting to fail as well.I took the module to Napa auto parts to test and they ran 3 tests but said it passed all 3 tests so I put it back in dist and started great when it was cold,ran great until it started getting warm and it started to cut out,stumble and died.Do you think I should replace it anyway? The dist. is 2yrs old as well as fuel pump,spider,spider harness,coil,plugs,wires,battery.It ran great until last week-end,What else should I do??

 

Yes, it could be the ICM. Bench testing is done with a cold module so could hide this fault.

I had an ICM go out on me exactly like this. Runs just fine, tests fine when cold. Once it gets warm it quits. Let it cool down completely and it runs again. It's hard to diagnose but a relatively cheap part and easy to get to. Just make sure you get the correct one. They can differ on the number of contact pins.

 

Good,morning,Yes I did replace the ICM yesterday with a new Echlin module and started up the Blazer. It runs excellent! Solved the problem! Back on the road! Thanks for all your help!! The ICM is new as well as a new Echlin coil so I might buy another module to have on hand.

 

Nice! also bonus points for keeping spares on hand.

 

Cool, that it was a relatively easy fix. Nice that it runs again.