FMU's

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July 18th, 2001, 04:23 PM
sullust

Ok, I need some help here. What is a FMU used for? I have a fuel pump that keeps up with the demand whether or not i'm on boost, so what else remains to be done with an FMU? I don't even know what the hell FMU stands for.

I'd appriciate some help on this.
July 18th, 2001, 04:41 PM
97SCGS

Fuel Monitor Unit, it works with the FPR to raise and lower fuel pressure for boosted cars.

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RevHard-2
T3/T04E Turbo,Spearco 30" IC,Tial Wastegate,Vortech BOV,Apex-i S-AFC,Thermal 3"Catback,3"test pipe,Greddy turbo timer,BBK 62mm TB,Walbro FP,RC 310's,B&M S.Shifter,Magnecor wires,NGK plugs,CS stage2 clutch
July 18th, 2001, 05:32 PM
sullust

what benefit is gained from an FMU? if your fuel pump is strong enough so that you don't run lean on boost, why do you need an FMU?
July 18th, 2001, 05:38 PM
newt2

Without an FMU you're either going to run waaaay to rich to even idle correctly on the low end or dangerously lean on the high end. Your ECU doesn't see boost, and wouldn't know what to do about it if it could. The only way to get more fuel under boost is to have a boost sensing device that can increase fuel to the engine.

As far as I know you can't run boost on a Honda without either an FMU or a standalone ECU. Every turbo or SC kit that I know of comes with a basic one, and there are better aftermarket ones out there too.
July 18th, 2001, 06:14 PM
Peyomp

FMU is Fuel Management Unit. It is a marketing word for FPR, or Fuel Pressure Regulator, which does what it says. Boost FMU/FPRs are used to raise fuel pressure for boost. They add a certain amount of extra fuel pressure per pound of air pressure the compressor on your engine adds (be it an eaton blower, a turbo, etc). The only way to not use one is to get a standalone engine management system, and some big ass injectors.
July 18th, 2001, 10:31 PM
sullust

ok. so the people that have had their JR FMU's stick were they talking about the FMU that came with the JRSC kit, or another FMU that JR offers?
July 18th, 2001, 10:43 PM
Sonnyballs

Actually, the Greddy turbo kit does not use an FMU. It uses an FCU (more marketing hype! http://www.hostboard.com/ubb/tongue.gif)

The kit comes with 310cc injectors and controls fuel by manipulating the MAP sensor voltage.

It's a decent alternative, but this approach limits how much boost you can run.

Sonny

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Sonny Van Hook ([email protected])
2000 Supercharged Civic Si @ 6psi
1999 Tonykart/Honda 80cc Shifter