Ok I took my car to the track for the first time. I have a 91 Z-28, hypertech chip adapter, edelbrock TPI base, trick flow twisted wedge heads, ZZ4 short block, HR276 roller cam. The car ran a 8.76 but it seemed to die 3/4 down the eigth mile. I know the TPI are not known for their top end but should it not at least make it down the eigth mile. I changed the fuel filter. Do you guys think it could be lack of fuel pump? OH and one more thing when you adjust a AFPR is adjusting it down inc or dec pressure? Thanks.

 

Adjusting the AFPR down (tightening the screw) increases FP. Do you have a FP guage? Make sure that you remove the vacuum line to the AFPR when you set pressure.

Not sure what your other issue may be.

-Schultzy

 

Not sure of the FP the problem is that it might need more fuel on top end but the idle is really rich, smokes really bad at idle. I think the only real way around this is to burn chips to adjust the fuel curve. I was gonna burn my own chips anyways but just wanted some info.

 

What was your trap speed and 60ft time?
With an E.T. like that you should be close to about 85mph in the 1/8.

 

I recently went thru a similar problem, after upgrading to AFR heads and a stealth ram mine was falling off over 5000 rpm. I burned several chips with increasingly richer fuel tables where I saw it leaning out, no change. Finally hooked up a fuel pressure gage and taped it to the windshield where I could see it while driving, took it for a run, and sure enough by ~4500rpm the pressure was falling. At 5000rpm it was down to 20psi, from 48psi where I had it set.

The Delco stock-replacement fuel pump just couldn't keep up any more, so I went with a high-pressure Walbro 340 pump...no more pressure dropoff.

 

I don't have the number on me right now but I know the 60ft time was like 1.96 and the trap speed was about 79mph. I might have to try that fuel pressure gauge while i'm running.