!992 k1500 4.3 won't start

125k miles on 4.3 won't start, engine spins over good.Changed fuel filter, ignition module,rotor and cap.Timing chain does not appear to have jumped. Have good spark,can hear fuel pump start.Engine will spin good for 20 seconds and then back fire and start TB on fire.Can pour gas down TB and it does the same thing,and will not start,no codes on computer,thanks,Doug.

If it's doing that I would check the timing.

I put a timing light on it but the white line at tdc will not show. Do I have disconnect some brown wire that I can't find? Or should I still be able to see the white line,thanks.Doug.

it sounds like your timing is 180 degrees out

the same thing happened to me

your firing order is 1-6-5-4-3-2

try crossing your plug wires on the distributor cap, to do that swap wire #1 with wire #4, then swap wire #2 with wire #5, the sawp wire #3 with wire #6.

Remember, only swap the plug wires ends on top of the distributor cap, leave the ends hooked up to your spark plugs the same

The only difference is I have a v8 in my truck but that should still work. Try it and see.

the roto was loose on the dist. shaft and that caused it to fire at the wrong time .Thanks for the help,Doug.