96 chevy 4.3 backfires

#1

my truck is back fireing when its warm new fuel pump, plugs and wires and new cap and rotor. runs fine when its cold.

#2

Backfiring through the intake? Or, the tailpipe?
Common causes are timing is off, or mixture is too lean, or valves sticking. Perform a vacuum test. Here’s how: http://www.international-auto.com/fiat-lancia-tips-on-reading-gauges/tips-on-reading-gauges-vacuum-gauges.cfm and this: http://www.secondchancegarage.com/public/186.cfm

#3

http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800bfe20

Then the next thing to check is worn spider injector assembly. Here’s what it looks like and where it’s located.

Tester