I just went to my local dyno shop he says my FMU is busted cause the actuator in the middle wont push downwards for the other disk to properly fit inside. Maybe the spring inside is busted. Anyone out there have this problem also?

Right now I'm using the 12:1 disk and still running lean at 7 psi of boost. 14:1 A/F. I need a standalone anyone wanna donate one for me?

 

TTT!

 

i dont think there is a spring. i took mine apart and all that pushes it up is the fuel pressure. the the metal cyl. pushes back down on it to clamp of the fuel. ill check later as I have 2 of them

 

I just recalibrated mine last week and it does have a spring inside.Maybe the spring got off-centered so it doesn't function properly.Do you have a fuel pressure gauge?I hghly recomend that you get one if you are using an fmu.Also do you have a high pressure fuel pump or are you using the stock pump?If you are using the stock pump that is your problem then.As soon as i switched my pump out for the new one my car ran 10 times better and doesn't lean out anymore.It would lean out on the top end so i kept the boost low until the new pump arrived.

 

Just as an update, we swapped the FMU in Herman's car this weekend with another vortech FMU. With the old fmu off of the car and opened up, the little center circle thing would pop up. You could pu down and the spring would pu back up.
With the NEW fmu, the center thing would stay down and only pop up when fuel pressure was applied to it. Everything runs great now, he even dyno'd the car monday with the 8:1 ratio and had a solid 12.5:1 a/f ratio (310cc injectors)
He's running a Walbro GSS342 btw.

-Xerxes