I am hoping someone can help me. My blazer was running very rough and you could hear it missing so we checking the timing and was told the chain needed to be changed. We have done that and everything is aligned as should be (we have rechecked), but now I seem to have no spark going to the plugs. We have changed plugs, wires, distributor cap, pick up coal, we have tested the coal and crack shaft sensor and they are both testing good. Before changing timing chain the truck would at least start now just turn over. Does anyone have any ideas what to try next? Please help

 

Are you absolutely positive you put the plugs back on the cap in the correct order? I've switched up a few on accident before, it gets confusing sometimes lol.

If you still have the old Timing Chain I'd put it back on and see if you are still having an issue. Who told you the timing chain needed replaced?

 

Thanks for the information I will recheck the plugs but don't have the old chain. Why would the old one make a difference though? just curious I will let you know about plugs

 

I assume

- you didnt disturb the distributor
- You lined up the crank and cam gears
- The only pertinent wiring disturbed was that for the CPS
- you get all the normal ECM lights on inst panel when you turn ign on. Like the SES

Take an old plug and hook it to the High V wire from the coil, lay it on metal and see if there's spark there when you crank.
If not, take off dist cap and see if rotor is turning

Power to coil? What is voltage reading?

Ign side of coil voltage varies in crank? If low or 0 volts disc that wire and read again. both side should be 12v. tap terminal you disconnected with grd wire, you should get weak spark {strong if you hook up a condenser from lawn mower}
That's all off top of my head

 

This is the firing order the wires need to be put in this order for the truck to run good or run at all

 

You didnt say anything about replacing the rotor. Did you? Sometimes the rotor fails even worse than the cap does.

 

Here's an interesting old thread:
https://blazerforum.com/forum/engine...gnostic-11774/

 

Yes we changed the rotor also, I feel like we have changed everything so far and yet keep hitting a wall grrr

Thanks pettyfog I will look into this. We put a computer on it and it said that the crankshaft position sensor was bad so got a new one put it on and yet still won't start Anyone any other ideas??

ok computer says it is code PO336 on computer that says crankshaft sensor but that is new now in book it says that code is crankshaft sensor circuit any ideas where to start on this? I am willing to try anything at this point

 

Are you 100% sure you put the reluctor back on? You did read the above post, didn't you

Pick up Coil dignostic

Really, if you didn't disturb anything else, you have to look there first.

Aaron

EDIT: you may want to work through the diagnostic

P0336 - CKP (crankshaft position) Sensor Circuit A Range/Performance

 

Sounds to me like the CKP sensor isn't seeing the reluctor ring gates... When you reinstalled everything, did you make sure to plug the CKP sensor back in? If there is no CKP signal to the PCM, there will be no spark. Have you tested continuity from all of the wires at the CKP sensor to their respective termination points (PCM, etc)? The wiring diagram is given in the second link aneill75 provided above.