I have a 1995 blazer with the 4.3 vortec. I bought it a few years ago and have been having problems getting it running since. The guy I bought it from said he put a brand new distributor in it (he did). For a while I could get the blazer to start but it would either idle high at about 3000rpm or it would die right back out. Turns out when he put the distributor in he didn't put it in correctly. Fixed his mistake so I thought but now the truck will crank for days but not start. If you step on the gas pedal while cranking, it stops cranking. Not sure if I didn't put the distributor in correctly or not. It has spark, has plenty of fuel. Like I said it would run before I tried to fix the distributor being out of alignment. Need help ASAP before I just junk it and lose money. Also I replaced the cap and rotor because the contacts in the old cap looked worn down.

 

Have you checked if the distributor is aligned properly by checking the rotor position with the crank at TDC?

Have you checked the fuel pressure?

 

Fuel pressure is fine. When I took the distributor out to fix the last guys mistake I made sure cylinder 1 was TDC. As I said I was able to get it to run before I did anything with the distributor. I'll double check this week and make sure but would that be causing it to stop cranking when I step on the gas? Before I adjusted the distributor it was cranking harder than it does now

 

Hmmm. So strange. I have heard of the need to let the ECU relearn the crank position settings but I've never personally had to deal with that.

 

Do you know of a site that explains how to do that? I saw a video where a guy said about removing two brown wires off the "ecm" but all he showed was checking the timing. I really feel it's a timing issue with this truck. I doubt it's the chain after a lot of things I've read about it being rare for the chain to jump but it's still a possibility for me. Another thing I've "heard" is that the distributor is defective. Me and my father are just kinda stumped on the problem but we're definitely gonna check the distributor again this week

 

To check if it's a timing issue, take timing out of the equation by disconnecting the ignition coil, then trying to crank it while you step on the gas. If it only stops cranking when you have the coil connected, it's related to the spark timing (distributor too far advanced?)

 

Alright ill try that as well. First I'm going to double check and make sure I have the distributor aligned correctly. After I do that I'll check the cranking. If it does the same I'll do what you suggest. If it still stops cranking with the gas pedal pressed and the ignition coil disconnected, do you have an idea what it can be? I really don't want to junk this blazer. Especially since it's only a little over 200k miles

 

Holding the throttle open will increase the cylinder pressure while cranking, but it shouldn't be nearly enough to stop it. I really think it's an ignition timing thing.

 

It was completely stopping for me. It would crank normal till I stepped on the pedal. The second I opened the throttle just a little it stopped. It sounded as if it wanted to crank but the motor would only turn a hair. Didn't have that problem till I tried fixing the distributor being out of alignment. Thats why I'm thinking I might still have it a little wrong. But im hopefully going back into it tomorrow

 

Well went back and made sure I did the timing correctly. After I finished that the truck would still crank but not start. Now as you're cranking it, it'll backfire out of the intake. No matter what it just doesn't start. I'm thinking maybe it just jumped time