96 AWD Jumped timing chain?

[martrem]

I recently had the tranny replaced in my 96 Blazer. While driving it home (and slowly climbing a small hill) the engine shuddered a bit and died. I tried to restart it and it turned over quickly, but there were intermittent clunks and rythmic slowing of the cranking for brief intervals. My first thought was that the timing chain jumped a tooth. I had the car towed back to the shop (very trusted) and they checked fuel pressure (over 60), spark (fine), and put it on a computer which showed nothing wrong electronically. They found 'TDC and checked the distributor, and he felt that it was pointing the wrong way. I wonder if the "cross pattern" distributor on my EDI system might have thrown him off? He talked to a local dealership and other contacts he has and they say that they have never seen a 4.3 jump time. I took it home and Found TDC for #1, reinstalled the distributor to #1 (he had moved it) and made sure that the intake valve had closed before reaching TDC (to be sure it was on compression stroke and that the valve train was indeed moving). It still won't start. Autozone says that if the ignition module was shot I would not get a spark. What about the cam position sensor? I had replaced it about 4 months ago while trying to solve a diffrent problem (ended up replacing the fuel pump and filter). Do the timing chains ever jump a tooth? is there some other sensor I should suspect? They say that it showed no problem codes. Please Help! this is my primary transportation.

[dnaplus2]

Let's see; Timing is good, you have good spark, you have good fuel pressure...

The next thing I would check is;
1) Injector Pulse, use noid lite on any injector connector.. For CPI system just disconnect the harness going through the plenum/intake and connect noid lite there. You should have a flashing light while cranking.

2) Check for Tach signal(rpm) during cranking, it should register something or you have a bad crank/cam sensor. You may need to use a scanner for that reading, but make sure you have a fully charged battery.

Try these and post again.

[martrem]

Okay, I connected the noid light to two adjacent contacts in the CPI harness end. The light blinked once when the key hit the ignition stop, but did not flash while cranking. I checked the resistance on the crank position sensor, and that was around 1100 ohms (the book says okay). I looked at the position of the distributor in relation to the balance wheel hash mark, and it seemed to be a little past the corresponding distributor post. What do you think the chances are that it might have jumped a tooth? If it did, couldn't I mash a valve by cranking it? Thank you for your response!

[BlazerLT]

If it is turning over quickly, you have jumped a tooth and are out of time.

[Fireplug]

Do this next its a fast and easy way to pin point if its fuel or ign problem.
Spray some CARB cleaner in the intake and then crank it over and is if it starts. If it does its a fuel problem (injectors fuel pump etc) If it will not start then start to look at the ign system

[martrem]

I appreciate y'alls replies and suggestions. Upon retrying the noid light on the injector harness, I got a flashing light. Okay, that's good. I lined up TDC again and the distributor rotor was a hair past the little pointer on the distributor case. It would seem to me that it should be either right on it or maybe just a hair before it...? I went ahead and tore down the front of the motor to the timing cover. This afternoon is the moment of truth to see if it jumped or not (hope so!). I'll let you know, and thanks again for your help.

[BlazerLT]

I'm pretty sure you jumped a tooth.

[2kjimmy]

doing a compression and leakage test is a lot less labor than tearing down the front of the engine!!

[martrem]

Okay, I had turned the engine to TDC for #1. I removed the timing cover (what a major pain, those oil pan bolts are hard to get at!). The marks on the sprockets were not lined up at all. Are the supposed to line up with #1 or is it #4? I turned the engine and was able to get them to line up at 6(cam) and 12(crank). I'm not sure if #4 was TDC at the time, although the mark on the Dynamic Balance Wheel that I thought was for #1 did line up with the pointer, it seems like it is on the exhaust stroke. I was at the limit of my stamina so I couldn't investigate further that night . Any suggestions would be appreciated.