90 5.7 Blazer starts right up and immediately dies.
 

I parked my blazer about 2 years ago to do some much needed maintenance and upgrades, but drive around the neighborhood regularly to keep everything flowing good. I started unhooking the positive battery terminal because my battery kept going dead from some unknown power draw. Recently I tried to start it and it fired up for about half a second and no fire afterwards. Getting fuel, but no fire. I can unhook the battery for a few hours and it will do the same thing again. I'm thinking it's either the coil or the spark control module in the distributor, but would love some input. I'm not rich, and can't afford to throw parts at it till it works.

Disconnecting the negative wire is safer and gives you the same result. If you are leaving the negative attached and just removing the positive you are just looking to accidentally short something out at best....

I'm not sure what to tell you about the no start, but work safe my friend!

I am going to guess this is a full size blazer? Or is this an s10 with a 350 in it?

1990 full size 4wd 5.7(350) tbi Silverado Blazer. I'm sure something shorted, just not sure what. The injectors are firing normal, just no spark after it fires up the 1/2 second or so it runs.

strange. i remember on newer s10s that would mean a bad crankshaft sensor, but doubtfull this one has one. my 93 has a knock sensor that is broken and still runs. its possible that ignition module is bad. ive seen them go out from time to time but usually they just dont start at all

I'm assuming we're talking about the same module,(the one in the distributer). I changed it about 8 years ago, and it is my prime suspect, it would run until it warmed up, then no spark until it cooled back off.

i had a 84 k5 blazer that used to blow ignition modules all the time (yeah the half moon looking thing under the distributor cap) it was like a once a month thing i just kept spares in my glove box. my problem was one of the ignition coil power wires was stripped and arching over to ground.

they are pretty easy to change. its probably that or the coil.... they do actually sell ignition module testers. i bought one at a flea market a few years ago but have yet to try it out. no idea if its still something you can buy