Ditched my in tank duel Walbro 255's for an external Aeromotive 1000 marine fuel pump. I also added an Aeromotive 100 micron inline fuel filter with a shut valve prior to the pump, also run an Aeromotive boost referenced FP reg set at 32 psi @ idle. At zero inches of vaccum the FP is @ 43 psi and goes from there.

Problem is, is with the cruise control on @ 55 mph, when the hickup accures, I've seen a loss of between 10-12 psi of fuel pressure which cause's a A/F lean spike/back fire. It only last's for a few seconds then the fuel pressure gets back to normal.

I spent most of my day today checking out fuel line restriction's and such.

Drained the tank, checked the filter and all was well.

What should I look at next?

 

how much vacuum are you seeing at 55? what is the fuel pressure?