Thoughts on curing my fuel issue

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
i run out of fuel with my car from roughly 5300ish on. my airfuel is dead nuts across the band, then from 5300 on it just tapers leaner and leaner. it is not super lean, but not safe to stay in it. here is my setup;

42's, matching maf, 255 lph high flow pump, stock fuel lines/rails.

i'm making 440/410 on a conservative dyno. we tried upping my fuel pressure, same deal. i can physically watch my fuel pressure gauge and once it hits 5300ish i start to lose pressure. so it's either my pump or my rails we think.

i know ALOT of people run this amount of power, without completely redoing the fuel system. so does this likely point to my stock rails giving out? i want to get this lean issue addressed and just run my stock 89' shortblock some more.

i will fix the leaning out issue, drop it down to around 420 rwhp and drive it this year hopefully. my combo is a simple trickflow h/c, systemax intake, vortech si-trim seeing 7.5 lbs.

so if it's fuel rails, what rails are worth the $$? i'd prefer to purchase a kit to drop in, but i know the bbk set is junk. give me your input please.
 
  • Sponsors (?)


Definatly not the rails! My brothers car has trick flow top end 42's and si trim. stock pulleys the car has seen 16 lbs. Granted it hasn't been on the dyno, but we did tune it with a wide band and pms on the street. the car has been 10.90 at 129 so far. full weight p/s and a/c w/ 2 12" woofers in the trunk. The only thing that i see different is he has the 255 in tank and t rex pump. I also have another friend who's been 10.30s with stock rails that made right around 500 to the tires. also has 255 in tank and t rex. I think you need a booster pump.
 
hmmm.. perhaps then. it is a toss up, i've seen it go both ways at this power level. the dyno is stingy, known stingy. i'm not trying to talk my power up, but it reads way low for everyone here that i know.

i don't mind doing whatever needs to be done. i just don't want to invest $$ into stuff i dont need you know? the pump manufacturer gaurantees them past my hp level, he even sent me a second pump for FREE to back this up.
 
In my experiance I've never seen a car make close to 500rwhp without 2 pumps or a fuel system. you have to remember to subtract about 20% from your flywheel number to get your rear wheel number so at 400rwhp your probalby making around 500 at the crank. honestly i know all about stingy dynos. we have one around me and we don't even use it anymore. we tune most of our stuff on the street and test them at the track. until people start racing dynos i'll stick to et number to tell power. If you can visably watch the fuel pressure drop off, that's telling me you need more fuel from a larger or additional pump, the stock rails will support more power than you give them credit for. like i said my buddies car went 10.30's at 134 like clock work 255 in tank and trex with stock rails
 
fair enough. as i said, im not a dyno racer. i really want this car to make LESS power so i can stop shifting it at 5100 rpm's and race this year. i'd rather make 400-420 and feel safer running it.

there is some t-rex's online new for cheap. i'm on it, pump will be installed by this next weekend. i totally don't mind spending whatever $$ is necessary, but i'm tired of burning it on wasted stuff.

props on tuning them on the street. i have tried to just watch my wideband and it rev's too fast. i can't make any full pulls past 3rd though.
 
Actually I find rails are a worthy upgrade at that power level, they help keep the fuel at those large injectors. Some find the inline pumps slow down the fuel supply behind a big 255lph pump. Does pressure hold steady above 5300?

I have made more power with a 42# and a gss340 (high pressure 255lph), stock lines and rails but up top it usually is a volume issue which is where rails come in.

I use the BBRC rails, they clear the dist and you can feed straight through. Youll also need a fuel reg as well and lines and adapters to go to the stock lines. I can prefab a kit for ya if you need help.
 
pressure steadily dropped. i just told him dropping dropping.. while he watched the screen and my a/f. i just looked over my dyno sheet and we only pulled it to 5700 to get 440/410.

damn car is making more power then i want.. i need to be able to rev it close to 6k i think at the end of the 1/4.