Sputtering on top of 3rd? Fuel issues?

[SpeeednV6]

I finally got around today messing with the beast. I swapped out my 237 reg. with my adjustable reg. I was trying to fine tune my stock adjustable wastegate with my RJC boost control valve. To make a long story short...I started upping boost with 93octane,15 psi boost, and 43psi line off fuel pressure. Everything seemed fine. Top of 3rd, my lowest O'2 were 800,812 at around 85mph, no knock. I started upping to 17psi, and I started what felt like a slight bucking. It wasn't knock because I was watching the Scanmaster closely. I got on it again and major knock (19* around 75mph) that went away the faster I went. I did notice earlier that when I installed my adjustable fpr, it was set at 50psi, line on and the gauge was bouncing. I lowered it to 43psi line off and put the line back on. 43 psi stood still on the gauge. I'm wondering with the car bucking or missing at aroung 100mph if it it the fuel pump?

 

[Bent6]

If you set your FPR at 43#s with the vac line off and it doesn't drop when you reconnect the vac line then you either have a broken vac line or the FPR is bad. Either would cause the symptoms you describe. The fuel pressure should increase at a 1:1 ratio per pound of boost over your base pressure of 43. In better words, you should have something like 39-40# fuel pressure at idle, 43# at 0# boost, 53 at 10#s boost, 58 at 15#s boost and so on. If the fuel pressure doesn't increase 1:1 with the boost, you will experience a lean condition which leads to bucking like you describe and eventually melted pistons and such. If everything is in order with the fuel pressure regulator, then a clogged line or filter or an inadequate and/or failing fuel pump would be the next suspects.

 

[SpeeednV6]

Yea, I think it's the fuel pump as well. When I did put the vac. hose on the fpr, the pressure did drop as it was supposed to. The filter and supply line are brand new (2 days ago). I had the same problem running the alchy and voltbooster yesterday. I decided to disconnect both for consistancy. Scanmaster readings were all good. I run NGKUR5's @ .30. Any boost over 17psi. and it sputters w/ or w/o alchy on. I will have to see if my gauge is falling at 18psi.