Am I running out of injector?

I recently swapped from a 3.125 pulley to a 2.75 pulley and have noticed that the car pulls hard at about 4000rpms and then seems to level off around 5000+. It never did this with the 3.125 pulley, it used to just build boost and power together. Now, it seems like the big surge comes on at 4k and dies at 5k. I used to see 10-11lbs, now I am seeing 15 at 5000rpms.

I have never had the car dynoed, so I don't know what my A/F is at.

Here's the combo:

S-trim (15+ psi)
38lbs Lucas injectors
Pro-M 80mm MAF with SC Tuning
FMU 6:1
Extrude Honed Cobra
70mm Tbody
Stage 3 ported TFS TW heads
Mild SC cam 217/222, .510 lift @ 114lca
Shorty headers- x pipe- Flowmasters with turndowns

I can't be sure that there is no detonation, it's too loud to hear, and my temp gauge is always super cold. (I have had other pingers and the temps usually skyrocket after detonation, I am not seeing this at all). I have a MSD-6 BTM and set the retard at .75-1

Any help is greatly appreciated.

It probably is BELT SLIP from such a small pulley.

Also, with no FMU my buddy just swapped back from a 2.95 to a 3.12 pulley on his 347 stroker with 42# injectors because he was running out of fuel.

So that is something to think about.

I'd get the car on a dyno also.

I just swapped on a 3.12" pulley from the 3.33" stock pulley on my combo, I want to see how it feels and then time for a dyno and maybe a new dyno-tune.

I know my car was running lean up top due to the C&L maf not keeping up when I was running a Powerdyne blower, I have 42# injectors and no FMU. With the S-trim I might have to switch to a Pro-M and it will still be close.

Good luck,

Howard

What is your FP @ wot? Id be suprised if it was going very pig rich with running that 6:1 FMU with 15lbs of boost and a 38# injector