Intake backfire

[Steven Robertson]

So I acquired a 99 suburban with the 5.7 a few months back and slowly fixing all the wrongs that the previous owners didn't care for and one of them being the ignition system. So from a stop to about 10-15 mph this thing falls on its face and then ROARS to life, fuel pressure key on engine off is 55-57 and running is around 51-53ish. It backfires bad through the intake pretty consistently. I'm thinking the pump is on its way out or the filter is clogged, anyone else think the same or is it just me?

[Brian Lindsey]

yes your pressure are low, but to cause backfire, not so sure , i think that would be a timing issue.

[Steven Robertson]

I thought timing too but according to my scan tool the timing is right where it should be and I'm not getting a pending or confirmed code for misfire

[KARNUT]

17 minutes ago, Steven Robertson said:

I thought timing too but according to my scan tool the timing is right where it should be and I'm not getting a pending or confirmed code for misfire

Check valve train. Push rods etc.

[HoosierZ]

If timing is good, then you may have an intake valve hanging open due to a bent valve or broken valve spring. A compression test will help find the problem cylinder or cylinders. Open valve means no compression.