S350

I don't know if this has been posted before or not. I recently upgraded the stock tbi fuel pump with a high flow factory replacement from Accel part#75703 (255 Lph). With the stock pump I was running 14psi with my setup and was working fine just found that at the track at around 5000rpm it seemed to run out of fuel. After I put this new pump in fuel pressure was 24psi, Ive adjusted the regulator to the max either way and the pressure will not buge. I know I don't have an issue with a return. Any input will be appreciated. My build is below it is in my 1996 S10:

Engine: 350
Pistons: Flat top Wiseco pistons with narrow rings
Rods: Eagle I Beams
Crank: Forged Steel Crank
Heads: World Sportsman II 64cc
Compression: 10.2:1
Intake: Holley TBI
Throttle Body: 454 TB and injectors
Distributor: MSD Pro Billet
Coil: MSD Coil
Plug Wires: Taylor 8mm
Exhaust: 1 5/8 Shorty Headers, duals
Chip: From Howell EFI

RBob

iTrader: (1)

Replace the pump with a 190LPH unit.

RBob.

S350

I installed an external regulator, used a block off plate in the throttle body and put an Aeromotive #13301 on to regulate the pressure down to a reasonable level. I took it to the track before and went 13.66 @98 with 24 psi and besides being really rich it ran fine. I updated the lines with -6 from the tank up and for the return. I now have the fuel pressure at 14psi and now it leans out and misses from 1300-2000rpm and will back fire, after 2000rpm it doesnt miss a beat. If I keep raising the pressure it narrows the range, I now have it at 20 and it does the same thing at 1800-2000rpm. It also doesn't do it all the time, it works fine I can drive it for 20 mins and then it acts up, almost like it a heat issue (under hood temperature). But with the 20 psi, it doesnt like all that fuel at idle. I have had the vaccum hooked up to the regulator also but it does the same thing. We tried chaning computers, MAP sensor, had the injectors flowed and sonic cleaned, checked for vaccum leaks, unhooked the O2 sensor, timing, distributor, even on the Tech1 everything is reading normal. Anyone with any imput is appreciated.

Thanks, Allen

camarorsssss

iTrader: (2)

I am in a similar situation as you are, although we have different motors and different set ups. I need to be running above 20 psi for my car not to lean out at wot but at idle that fuel pressure is very rich. I was told to upgrade to the vafpr and ebl computer system in order to get it running properly. Here is the posting.
https://www.thirdgen.org/forums/tbi/...-pressure.html