1996 k2500 7.4l vortec

[Evan Frericks]

truck won't start backfires out intake. Replaced maf egr crank sensor timing chain fuel filter. I'm getting spark. I'm getting fuel. Have a vacuum Guage and it has no vacuun leaks and reads a steady 22 psi

 

[454cid]

Where are you connecting a vacuum gauge?

Have you gotten the engine wet recently? After pressure washing mine for years, it's started getting sensitive to water, so something that used to keep water out of something is getting "old".

Are you getting any codes?

Did this suddenly happen? Did all the stuff get replaced because of this, or was there something else going on?

Usually when my truck won't start it's the Ignition Control Module. You said you have spark, but you might pull it and take it to Autozone to get tested.... they have a machine that will do it.

 

[Elroy]

i learned to put a timing light on and try more that one cylinder to make sure i have spark, my distributer sheared off teh teeth of the gear at the bottom and stopped spinning, so i had spark on just 1 cyl

 

[Evan Frericks]

Where are you connecting a vacuum gauge?

Have you gotten the engine wet recently? After pressure washing mine for years, it's started getting sensitive to water, so something that used to keep water out of something is getting "old".

Are you getting any codes?

Did this suddenly happen? Did all the stuff get replaced because of this, or was there something else going on?

Usually when my truck won't start it's the Ignition Control Module. You said you have spark, but you might pull it and take it to Autozone to get tested.... they have a machine that will do it.

I'm not getting any codes and it hasn't gotten wet

 

[Schurkey]

truck won't start backfires out intake. Replaced maf egr crank sensor timing chain fuel filter. I'm getting spark. I'm getting fuel. Have a vacuum Guage and it has no vacuun leaks and reads a steady 22 psi

You have spark...where? At the end of the plug wire? You need spark across the spark-plug gap. If the plugs are fouled, you don't have spark across the gap.

How do you know you're getting fuel?

I wouldn't know how to use a vacuum gauge to test for vacuum leaks unless they were fairly huge. At least it's steady, that's gotta be good. I'm surprised you can generate 22 inches of vacuum (Not psi) while cranking.

IF (big IF) you have fuel and spark, and assuming you have the right amount of fuel, and the spark comes at the right time, all that leaves is compression and exhaust.

First guess: Fouled plugs perhaps due to age, a weak coil, or other ignition issues.
Second Guess: low fuel pressure

 

[Roger Stephenson]

It sounds a lot like the symptom of being 180 degrees out with the distributor.