I have been driving my 94 S10 Blazer problem free for a few months since fixing some issues before winter. The other day I drove to work and all was fine, when I got off the truck just cranked and would not start. After trying a few more times it was like my battery was dying and I was left with just clicks or nothing. I tried putting in a spare battery from my garage but same result. Truck would also not start when trying to jumpstart either. I ended up having the truck towed home so I could dig a bit deeper into the issue. I had the battery tested and it came out fine. I then suspected the starter which I removed and it also tested fine. Not wanting to go through all the hassle to put the old starter back in, I ended up putting in a new starter while also running new battery cables as well. After putting in a fully charged battery I still got the same result, truck slowly turns over and continues to get weaker every time I try until I left with just rapid clicks from starter or nothing. I checked the ground strap from back of block and cleaned it up. Also cleaned up connections to the alternator as well. I can put my battery in my other vehicle and it starts right up no problem. I have also checked fuses and don't see any problems. so to break this down:

1. Battery tests fine and will start other vehicle just fine.
2. New battery cables and also cleaned ground strap from back of block.
3. New starter even though my old one tested fine as well.
4. Alternator was replaced less then a year ago.
5. Fuses checked and look fine.

My next thought was the ignition switch possibly, or am I completely missing something else. I know many cables in the truck have fusable links but the ones I have found seem fine. Are there any other grounds I am missing? It just boggles me that this just all of a sudden happened with no indication. Wiring has always been my kryptonite when it comes to fixing my vehicles

 

Did you check fuel pump? Not sure if I just missed reading it, but it doesnt seem to be mentioned... wife's sonoma died on her at a red light, thought it was electrical, ended up being the pump...

 

First things to check:

Fuel - does the fuel pump run for a couple seconds to build up pressure (Key only in "ON" not to "START")
Air - Check all airways and the air filter plus the pre-heat and pre-heat flapper on the filter assembly. (Assuming it's a 94 TBI - the CPI is slightly different.
Spark - Check if you have spark at all. (Best done with a spark tester but backyard methods work as well)

For further we would need to know the type of injection TBI or CPI.

 

Just for a little more back story on truck. It is a CPI 4.3 which has had both the spider injectors and fuel pump replaced. Before winter I wen't through a lot on the truck including:

1. All new exhaust from manifolds back
2. New distributor, ignition coil, plugs and wires.
3. Replaced coolant temp sensor, TPS sensor, IAC sensor, knock sensor, and MAP sensor.

It was running great until this episode. I am thinking it is something electrical, as even with a fully charged battery, the engine doesn't seem to spin fast enough to start. It only takes a few times trying to start it that it will turn into just clicking from starter or nothing at all. I already ordered an ignition switch as it is cheap anyway and also have another coil I can test with as well. It just seems like the starter is not getting enough power or truck is losing power as soon as I turn the key.

 

Does your engine spin freely by hand?

Sounds like it is binding, or wanting to seize up.

Alternator pulley? Water pump pulley? Engine itself?
Got oil in there?
Ran it real hard before you turned it off?
Engines with bent rods can be hard to start, but they will.. sometimes?

 

I did get on the crank bolt and was able to turn the engine by hand. I will take the belt off and check the individual pulleys next time I get to mess with it. It ran perfectly fine before with just regular driving, nothing out of the ordinary to place extra stress on the engine, so I don't think it's anything catastrophic. Another thought I had was possibly the crank position sensor going bad

 

Unfortunately it looks like my engine may be toast. I was able to get it to fire today after swapping ICM in distributor but couldn't keep it running. When I wen't back to engine I noticed a wet spot on ground with oil. At first I was thinking one of my oil cooler lines was leaking but soon realized that my air filter housing had a puddle of oil in it. It looks like the engine has a good amount of blow-by all of a sudden and the lack of compression could have been my starting issues. I am thinking piston rings are shot but will see. I am going to clean everything up and do fresh oil change with new spark plugs to see if anything changes.