Help my 1987!!

[ChevyTech]

Backfiring is not a common problem on TBI trucks.

If you ruled out the ignition system, you should look for a mechanical cause for the problem.

An intake valve that is not sealing or a flat cam lobe can cause backfiring.

If the problem is an intake valve not sealing it should show up on a compression test.

To check for a flat cam lobe you could remove the rocker covers and see if one of the rockers is not moving like the rest of them.

[Gregs71]

Well today, I took the truck out again. When its cold I can rev it up over 2,000 rpm with out any issues. Once it started to warm up it would miss/sputter and have some backfiring.

When I got back to the driveway, after putting it in 'park', I revved up the motor. There was maybe a slight(maybe delayed reaction), but it revved up just fine with no noise. I revved it to 2000, let it drop to 1500 and back up, etc with no issues.

I guess it is only doing it under a load. I guess it is starting to look mechanical.

I guess I'll have to pull the valve covers and look for odd movement.

Greg