high fuel pressure

texas-buzzard

texas-buzzard

Registered
I am running a BEGI fmu but the lowest fuel pressure i can get under boost is 105 lbs. the needle is out 4 turns and will not change the pressure. i am running 6lbs of boost. any ideas?
thanks
 
What are you trying to do? Set a lower base psi or reduce peak fuel pressure or adjust the rate in which pressure rises?
 
texas-buzzard said:
I am trying to lower my peak pressure to around 95 psi. Is 105 lbs to high for stock injectors?
Click to expand...
around 90 +/- psi is where you want to be, you could turn in your adjuster a hair. But any changes should be made on the dyno under load to be sure your AFR remains safe. Be sure your gauge is working properly first by checking it with another gauge.
 
I am running an Innovate LC-1. my A/F under boost is 11.8:1. Turning in the needle would raise the pressure, i want to lower it. Is my A/F correct?
 
I am referring the rise rate screw, in would slow the rate. Big question is something wrong?
 
As far as the shim, i have had the fmu apart several time but could not find a shim. what does it look like and where is it located? The A/F is good under boost but i am concerned the injectors will lock up at high fuel pressure. I know fmu's are troublesome but i can't afford to upgrade to a 1:1 reg. RCC has an fmu, how does it measure up?
thanks for the replys
 
i have similar problems hit boast and right away over 100psi but af is good go figure

IMG_2720.jpg
 
UPDATE: I finally found the shims and discovered the upper one was bent and the lower was bent and cracked. I made a .010 shim and installed on the lower side of the diaphram against the in-out block. I set the low side at 40lbs at idle and it remained stable. I will check the bike under boost tomorrow, but i am sure the problem is cured.
Thanks for the advice:thumbsup:

Picture (Medium).jpg
 
Last edited:
texas-buzzard said:
UPDATE: I finally found the shims and discovered the upper one was bent and the lower was bent and cracked. I made a .010 shim and installed on the lower side of the diaphram against the in-out block. I set the low side at 40lbs at idle and it remained stable. I will check the bike under boost tomorrow, but i am sure the problem is cured.
Thanks for the advice:thumbsup:
Click to expand...
Be safe and get a new FMU, cracked once it will again...good news though.
 
Yea, if this fix doesn't last i will get one from RCC. Hopefully i can upgrade to secondaries or a piggyback setup later this year.
 
GPW said:
Be safe and get a new FMU, cracked once it will again...good news though.
Click to expand...
actually that is what is usually done is replace with a .01 shim
its just what fmu's do always has
thats why they sell a rebuild kit lol
 
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