fuel press to low for 50lbs

[crazygn]

Right now my sig at the bottom should be right , i run a ta 54 , power stroke intercooler , 206 cam , 50lb injecors , and a turbo motions intake manifold . At 17psi boost i am running 33psi with the vac line off , if i take it higher or lower i get knock in the red on my knock gauge, with it set here it will light one or two lights in first and 2nd but none in 3rd. Right now iam running a joe L 93 chip at 20* this is on 93 pump gas.


is this way to low of a fuel press, my blms are still at 105 and wont go higher.

thanks for any help

 

[turbo buicks]

Originally posted by crazygn
At 17psi boost i am running 33psi with the vac line off

are you saying you are running the car w/the vacuum line off the regualtor all the time? you are supposed to set the base fuel pressure at idle with the vacuum line off. then reconnect the vacuum line and take it out for a spin. the vacuum line is to increase the FP along w/boost. 1 psi boost=1 psi FP. dont drive around w/the vacuum line off.

 

[turbo buicks]

also set your FP from 43-45 psi vacuum line off. ive heard it said that you shouldnt exceed 50 psi of base FP so as not to put too much stress on the fuel pump and if you have to exceed 50 psi w/the vacuum line then something is wrong. especially w/50's IMO.

 

[crazygn]

no , no i set the fp with the vac line off at 33psi and put the vac line back on and it runs the best there, if i go any higher or lower i get bad knock. But i thought i would need to set it around 40-45psi with the vac line off but it seems to run to rich and get bad knock. Isn't 33psi with the vac line off way to low, that means it is probably running 20's with the line on.

just sounds way to low to me.

 

[turbo buicks]

something definately sounds messed up b/c the car should run crappy on that FP. i say check your guage w/a direct guage off the end of the fuel rail and check your regulator. i use an oil filled guage w/a steel braided lineand it works good b/c engine vibration cant affect the readings

 

[crazygn]

i have a braided line off the rail and a little cheap gauge , i'll have to check it, this could be part of my big power loss problem , it seems to stop pulling after 4600 rpm and die soon after that. I run a billett alum reg, 307 pump and 50lb injectors with about 1500 miles on them , every thing is pretty new .

think it could be a fuel problem

thanks for helping

 

[turbo buicks]

you say its weaker after 4600 RPM? isnt this also a sign of weak valvesprings?

 

[crazygn]

yea it pulls hard from 3300 to 4600 then just does not seem to pull hard . It has new cam , chain and 90lb valve springs in it. Also i cant seem to get the blms up stay at 105 all the time no matter with the fp is. Also with all the new fuel press stuff it seems to hold press down to 0 for about 20 mins.

it did pull very hard for about two days then loss the hard pull on the top end , this is with my new set up, maybe some thing in the fuel system want wrong.

 

[turbo buicks]

PTE recommends a 3K stall minimum for a ta-54. think this might be the problem or not b/c you got a 2800 stall going by your sig.

 

[crazygn]

i run my brothers th350 trans with a tci 2000 stall tell mine gets fixed. Will a stall kill you top end if its to small. Wont hold much for rpms 5000 is pushing it hard and fells like not much power after 4600 rpm.

 

[turbo buicks]

im not sure b/c im not that smart yet trannies are not really my forte so i cant give you a definite answer but im certain if you posted in the tranny section and/or asked Bruce (WE4) the tranny section moderator he could give you definite answer.

 

[REDS HOT AIR]

i've been running a 2800 stall with my 70 turbo...yes it will cause lag but wont hurt nothing once it hits boost.

if you cant get blm up at that low of fuel pressure then you need to possibly getting some fuel cut back in the chip.

the computer can still adjust fuel at idle with blm there so its not a big concern.

you should be concerned about 02's at wot in 3rd gear...at 33# base its got to be lean as hell once the blm's lock at wot

it does lock at 128 at wot dont it??

and what is you maf reading at idle and at wot ???

 

[crazygn]

i'll check what i have saved on the disk, my t link wont read right and i have to send the cable back. I dont think the blm move at all even at wot. My scan tool read 780-790 from 33pis to 42 psi fuel press , i hope its the scan tool reading crazy. Thing is that if i run any thing higher then 33psi w vac off the knock gauge reads in the red. Where its at now might light one or two lights at the most.

i gotta get some sleep , i'll be back after work and i'll check the disk and see whats on it as for maf .

 

[turbo buicks]

have you considered that maybe b/c the higher FP makes the engine run better (and stronger) it might be causing it to torque over more and move around more than when it runs crappier and so it might be causing some false knock like at the down pipe/header area for example?

 

[turbo buicks]

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3.8 Turbo Buick Valve Springs 0022
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HTH

 

[crazygn]

i have the LT1 springs but i think there set at 90lbs, i wish it was the springs or i know what it was so i could fix it its driving me crazy.

 

[TurboDave]

Originally posted by turbo buicks
you say its weaker after 4600 RPM? isnt this also a sign of weak valvesprings?

Weak valve springs wont show up until WELL over 5,000rpm

 

[Chuck Leeper]

Sum suggestions!!

Do yourself a favor and get the car back to where it should be before you try to change anything else..
So far, I've seen:
1. Wrong trans and converter.
2. Gauge is questionable.
3. The scan tool is fubar.

The other problem appears to be that you are reporting the engine dies after it hits the 4600 rpm and flattens out...Fuel is going away or the ign is gone..??
I'd suggest you park it before you find the crank on the ground and lots of "shiny $hit" in the oil pan!!

Just some advice from an ol fart that learned the hard way too!!

 

[crazygn]

ive tryed other coils and all and the same thing, the gauge will go up pound for pound to so the fuel press looks ok. My maf readings on the tlink are idle 775-800, 6-8 ghp and wot at 17psi at about 4700-4800 rpm , the highest i seen it was 208 ghp. Dose the maf look low.

it did run better with the cold air to night.

 

[REDS HOT AIR]

time to try another maf


you have plenty enough stuff there to max the maf..

it should read right at 255 when up in boost