I finally got around to replace my Plenum gasket using the Hughes plenum kit. While doing so, I also replaced: timing chain and gears, distributor cap and rotor, spark plugs, water pump, pcv valve, and belt.

The problem I am having is when I started it up, it sounded fine at first, but it backfired a few times. I let it run for a little bit and then shut it off. I tried to start it again and it would just crank but not start.

I think I am having a timing issue. I did not remove the distributor at all. I did it all by the book, I put it at TDC, rotor was pointing at #1 spark plug, and lined up the timing marks when I removed the old timing chain/gears, and did not move the crank/camshaft at all before putting the new timing set on. The only problem I had was the new timing set I got from Cloyes had both timing marks at the 12 o'clock position when installed, when they are supposed to be pointing at each other (12 o'clock, 6 o'clock).

I am wondering if I could have misread the timing marks on the old timing set because they were covered in grease and be 180 degrees out? But how could it be when the rotor was pointing at #1 spark plug and I did not rotate the shafts? Maybe I can be just a few degrees off when I installed the chain?

I also broke the small plastic vacuum line that goes from the intake manifold to into the firewall to the cab, but I don't think that has anything to do with it.
This is in a 2000 1500 5.2L by the way...

 

Double check your spark plug wires, since you changed the cap and rotor - make sure that they are in the correct terminals in the cap and correspond to the engine's firing order.


The timing chain set should have been installed with the crank gear timing mark at 12 O'clock and the cam gear timing mark at 6 O'clock with the motor at TDC.


Also, fix the issue with the broken plastic line to ensure you don't have a vacuum leak.

 

I will check the wires tomorrow, but I am pretty certain I got them correct because I labeled them.
I know what way the timing marks are supposed to line up, but they didn't work out that way when I installed them.
I am also going to get a line to fix the vacuum line.

 

With the marks on the gears at 12 (crank) and 6 (cam) cylinder 6 is at firing position. You did the timing gears right. If you were 180 out, it wouldn't run at all, and would backfire quite nicely.

Recheck firing order like Atomic suggested. It's easy to screw it up. (ask me how I know. )

 

are you sure you didnt rotate the cam any while putting the new chain on,possibly a tooth off????also,not sure how long you have owned the truck,but,could the timing(fuel sync) have been set previously with the old chain?now that you have a new timing chain with no slop,this can throw your timing(fuel sync) off,possibly causing the backfire..

 

Well I got it to work! I had the 2nd and 4th spark plug wire mixed up! Sometimes it's a simple mistake.
Thanks guys! I would have not thought of that first, and would have probably took it all back apart.

 

the timing gears are keyed anyways, cant really put them on wrong :P

 

Thanks for posting the step-by-step details of what you did - that made it easy to provide meaningful suggestions - besides, I made the same mistake myself in the past and I never forgot it :-)

 

As have I, but, I still seem to be able to repeat that particular little mistake.