No ignition spark?

1995 chevy silverado 1500 350 tbi. Has been starting at times then not starting. Has never died and runs great when started. When not starting there is no spark and injectors not spraying. Has to be something intermittently not sending power to these systems. Not sure what it can be.

Truck listed above is a C 1500. It was driving fine down the road it seemed to backfire and then shut off. Been check out things; I have fire to the coil and distributor cap, but not to spark plugs. The ICM pickup coil all seem to be working fine. There doesn't seem to be anything wrong with cap or rotor that I can see. However, still no spark at plugs. I am starting to get lost and don't know where to go from there. If I should replace cap and rotor or need to see if timing chain has jumped time. Any help would be gratefully appreciated since this is my only vehicle. Thanks for any help.

Roy,

Yes, the rotor turns when the engine cranks over and the distributor was tight. I tested the pick up coil with a multi meter at the connections on ac volts they bounced between 0.3 and 0.4 volts. I checked the module by checking if it had switching signal at the coil with test light and piercing the case of wire there was signal the coil was tested with plug on the distributor wire and plug it was grounded and strong blue spark at the coil.
Thanks for responding hope you can help.
Patrick

Okay, is there any way to check either the cap and rotor without replacing them? The wires are about two years old. The cap was put on in April this year. Rotor I do not remember if it was at same time or not for sure since money has been tight and that was back six months ago. A lot has happened since then. I hope you understand what I mean by that.
Pat

Went out to start my truck and it just turned over. Checked the throttle body and no fuel. Got a tester and no spark. No thing from the coil, replaced coil still no spark. Checked codes and all I got was 43 knock sensor but I have been driving it for six months without a knock sensor.

Okay, I have the cap looks brand new like just put it on and the rotor same not burnt or anything it all looks good. That is why I was wandering if I should worry about it jumping time?

Thank you for your answer Ken. I have a 1992 K1500 4x4 5.7L and it stalled on me while driving it started again after 10 minutes was fine for awhile. Then stalled again and would not restart. No spark. I replaced the ignition module and I am good to go!

Okay, will try that. Would that stop spark at the plugs from the cap? I forgot to say the engine had been rebuilt and I dropped it in back in 2015. The guy that built it was a stock car motor builder.

Okay, I will have to find a compression tester and then test them.

I put a small block 350 tbi crate motor in my truck listed above. At first crank the engine fired and started for about 3 seconds then backfires spitting fuel out the top of throttle body and it hasn't had any fire since. Replaced the distributor/cap and rotor with new pickup coil new ignition module and plugs/wires. Still nothing. Replaced ECM and coil pack. Nothing. Replaced the ignition switch after I did research and found that I wasn't receiving power to the ignition relay on the fuse panel in the cab. Nothing. I'm still getting no power to the ignition relay in the fuse panel. The dash lights work. The motor cranks smoothly but doesn't get spark to none of the cylinders. I've also realized the fuel injectors doesn't seem to be firing as well after the backfire which makes me believe it's an ignition problem yet I've replaced every ignition part I know of.