Stirgen

I am trying to diagnose a no crank condition on my 96 Blazer (4.3L V6 Vortec) I blew the head gasket which i replaced. After putting everything back together I pulled the codes on the engine before starting and no trouble codes were indicated.

When I turned the key it turned over briefly, but heard a single misfire and/or detonation (Boomffff!). Checked fuel lines and found lines were not properly secured to injector assembly. Reattached fuel lines properly. I dont believe the engine has completed even one full revolution since it was oput back together.

Battery was dead so i replaced it with a good one. Turned the key again and I can now see the fan blades moving a little so I know the starter is trying to turn the engine over but it stops quickly with a "chunk" and wont crank at all. Repeated turns of the key produce an immediate lock up with a "chlunk".

The engine will turn (with difficulty) by hand so its not completely locked up. Could trapped air in one or more cylinders prevent cranking. ? I dont believe the engine has completely turned over even once and i believe that the intake and exhaust valves are still in a closed position on one or more of the cylinders.

I will remove plugs tomorrow and try cranking it again to see if that is the problem. Next step will be to verify spark and do compression check. Anyone have any other insights or suggestions?

shawnvw

I would first pull all the plugs like you said and try cranking it. It could be Hydrostatic Lockup. In other words, antifreeze in the cylinder with both valves closed.....and since water doesn't compress it will totally lock the motor up.

And i know its a dumb question, but it must be asked.....you didn't drop a bolt in one of the cylinders????

Stirgen

Thanks for the reply.

I pulled the plugs and then turned it by hand. A lot of gas came out of the cylinders so i pretty much flooded it the first time i turned the key. It must have been locking up hydrostatically. I then turned the key and the engine began turing over easily with no problems so the starter is working OK and i didnt damage any gear teeth which had me worried.

i was going to check the plug wires for spark but since i had so much fuel laying on the ground I said forget it. No reason to risk turning it into a fireball. I will let it air out for a couple days and get a spark tester thats safe.

I have to disable the fuel pump before checking for spark though because it dumps fuel into the cylinders like mad. I want to stop wasting fuel and prevent a fire hazard. I was going to pull the fuse for it (i.e. ECM BATT) but the fuel pump circuit is also part of the ECM so if I pull the fuse to stop the fuel pump I also disable the computer.

Without the computer - No crank. I am looking for another way to disable the fuel pump like disconnecting the plug connector at the tank but I am not sure if there is one there and it may not be accessible.

shawnvw

If you hold the gas pedal all the way to the floor while cranking, it will prevent the injectors from firing