setting the FMU

[po-po 5.0]

about how many turns should I take out the FMU for 36# injectors. My manual only mentions 30# ers.

[po-po 5.0]

nobody uses an FMU at ALL?

[kobra94]

i have 42#'s and i don't use mine at all. i tried it a various settings and finally gave up and removed it. car ran pig rich all the time, and wouldn't start when it was warm. Ken

[klondike93]

I guess I'm a little ignorant about the FMU, isn't it only used when under boost?

[kobra94]

hmmmm, you could be right. never thought of it like that. but since i removed it the car does run better. wonder why? ken

[po-po 5.0]

When I finally get around to affording to tune the car, I think I'm still gonna use the FMU, and set it 1:1 to mimic cartech's boost sensitive regulator.

[kobra94]

hmmmmmm, now theres a thought. let us know how it works out. ken

[pablo]

Dear PO-PO 5.0:
I use the FMU with 24 injectors and 12 psi of boost, and it works perfect!!!
I get about 85 psi of fuel pressure under full boost, and have no complains ....
I use 75 mm throttle body, thypoon intake, 76 mm CL air flow meter...
The FMU from procharger is boost sensitive, restricts the fuel return line depending of the boost.
The best way to adjust the FMU is to have a fuel pressure gauge installed, try to go with only half a turn and see how it works, keep your eye on the fuel pressure and make sure it goes up once the boost comes on.
Be sure it goes back to normal pressure when boost goes off .
Of course the FMU will only work if you have a GOOD fuel pump of about 255 lph.
I hope my humble comments helps you.
Best regards
pablo

[po-po 5.0]

I know how the FMU works, but the ATI manual doesn't mention any type of setting for 36# injectors. In reality, I don't need the fuel to come up very much. I basically set the thing for 30# injectors, and have just driven it pig rich for the time being. I have a fuel pressure gauge, but not a boost gauge (sad huh?). the fuel pressure comes up a bit, but since I don't know how much boost I'm making its tough to say what the rate is!

[WA2FAST]

Well, since you have it set at #30 injectors, all you would need is to play around with it from there to turn down the FMU a bit under boost... you'll just have to screw around with it till you get it right. A boost gauge might be a good investment :) Good luck with it.

[po-po 5.0]

Originally posted by WA2FAST
Well, since you have it set at #30 injectors, all you would need is to play around with it from there to turn down the FMU a bit under boost... you'll just have to screw around with it till you get it right. A boost gauge might be a good investment :) Good luck with it.

A boost gauge, a twEECer, and a wideband. I just have to get rid of a few things out of the garage so I can afford all of this.

[WA2FAST]

Yea, I hear ya. I have a TON of things in my garage that I need to snap some pictures of and sell here soon too. Too much stuff that is worth good $$$ and other people could get some good use out of and I need to fill the hole in my pocket too :)

[pablo]

Dear PO PO 5.0:
i forgot to ask you about the air flow meter on your car...I hope you have the air flow meter calibrated for those 30# injectors..if not you might have a very rich condition.
Just wonder..
Take care.
Pablo

[po-po 5.0]

its a C&L, and it has a 36# sampling tube.

[pablo]

Dear PO PO 5.0
Glad to hear that you have a CL calibrated unit for those big injectors...36 injectors are big, and you would need a good flow heads, and some more to handle that kind of fuel.
By the way,...you are using the white restrictor and check valve on the procharger FMU? if not you would have problems when you decelarate the engine, since the fuel pressure would be very high once you lift your foot form the pedal.
Take care
pablo