We did a complete rebuild of the 4.3 a few years ago. New pistons, rods, bearings, block was vatted and machined, port and polished heads, the whole nine yards. We put it all together and after messing with it for weeks we couldnt get it to fire over. it definitely is getting spark, fuel, and has compression and in time. I am completely stumped on what it could be. My guess is some sensor somewhere (cam, crankshaft positioner or crank angler?) on the engine has failed and it is just causing the entire motor not to run, however I have no way of knowing which one it could be or where since this was before OBD2 and im not just going to replace every single sensor blindly.

I am stumped. I have no idea what to do to get this damn thing running. any help would be greatly appreciated..

 

The only thing a bad sensor could do is cause it not to get spark or fuel. If it's getting spark and fuel, and it has compression, it pretty much HAS to be out of time.

 

Depends on what you mean by has fuel. Do you mean fuel rail pressure or have you checked injector function?

How do you know that the ignition timing is right?

If you are sure that you have adequate fuel pressure during cranking and that you have proper spark with good timing then it may be the injectors. You can test for PCM injector pulse control and then fuel delivery for each injector with a pulse box. Here is the total process for a crank, no start problem:

https://blazerforum.com/forum/2nd-ge...rticle-103750/

I am with Don, don't replace any sensors unless you know what's not working first.


George

 

I would love to take credit lol...

But I'm sure it's Tom, and not me.....

Good luck with the no start...

 

Ooops, sorry. Yes, Tom.

George