So... Wife and I were riding down the highway and the blazer literally stalled at going 70mph. Cranks but wont start. Changed timing chain, made sure its all lined up, #1 piston was TDC (top dead center), still no start. Changed ignition control module, brand new distributor, brand new alternator, and Crankshaft Position Sensor, starter is getting power, fuel pump is working. Checked everything with a test light except the ignition switch... Everything is getting power.
go to start it, it acts like it wants to turn... Just not gettin there. Anybody have ANY friggin clue what this problem could be? Any input would be great. I need this thing back on the road ASAP

 

Sounds like the distributor might be 180 degrees out. When you aligned #1 on TDC, how did you confirm that it was the compression stroke?

Also, why did you replace the timing chain? Did it break or skip time? If not, maybe the original problem is still present.

 

If you want to verify #1 cylinder is TDC on compression stroke an easy check is loosely rollup a small piece of tissue paper and put it in the #1 cylinder hole so it just stays put. When you hit TDC comp. stroke the tissue will fly out. Then just make sure you're timing marks line up.

 

I confirmed ot was TDC and on compression stoke by turning the crank pulley until it started to get extremely tight. I dont have a timing light so I had to do if the old school way. The old chain is about an 8th inch longer than the new chain so it didnt break but it stretched. When I pulled it apart it was obvious that it jumped at least 2 teeth. And yea. When I get home tonight im gonna put #1 TDC and then make sure my notches are lined up and see where my rotor button is pointing. Its gotta be out of time on the chain or in the distributor. Im getting fire from the plug wire oit of #1.

 

The easiest and most reliable way to confirm it's on the compression stroke, IMO, is to have somebody stick their finger in the spark plug hole while you turn the engine by hand. When air blows out, keep turning until the timing marks line up. Obviously, you want to make sure you turn in the normal direction of engine rotation.

BTW, there are a couple of different timing marks. Make sure you're using the right one. You'll still get spark from #1 regardless of how far out of time it is, so that isn't really telling you much.

There's some good info here.

 

Well... it was the timing; shes running again. but who wouldve ever figured you have to be TDC on NON-COMPRESSION stroke with the 4.3L non-interference engine?

the fact that I was getting spark off #1 told me a lot actually. Because we didnt know if it was electrical/fuse related or what. the old timing chain was definitely stretched and worn out.

unfortunately, I believe the spring in the tensioner has went bad because its jumping a lot, and i can move it around by hand. im assuming its the spring in the tensioner... but I aint no genius on these 4.3Ls



obviously