BMW K bikes (Bricks)

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1Back to top Go down   Fuel pressure regulator Empty Fuel pressure regulator Tue May 31, 2016 7:52 am

Gauntlett

Gauntlett
Silver member
Silver member
As my trike has a non standard system, it has an independant fuel pump which is switched one at ignition turn on, it constantly runs and returns to the tank constantly via the original FPR, in this cenario does the vaccum connection to the FPR actually do anything.

    

2Back to top Go down   Fuel pressure regulator Empty Re: Fuel pressure regulator Tue May 31, 2016 8:16 am

Holister

Holister
Life time member
Life time member
Yes it does. While the operation of the fuel pump may not be standard, the FPR will function the same and that goes for the vacuum tube as well. Without it your fuel will run a little rich under accelereation


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fuel pressure regulator Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

3Back to top Go down   Fuel pressure regulator Empty Re: Fuel pressure regulator Tue May 31, 2016 8:36 am

Gauntlett

Gauntlett
Silver member
Silver member
Am I to assume from that, that the fuel pressure is reduced slightly under maximum vaccum.

    

4Back to top Go down   Fuel pressure regulator Empty Re: Fuel pressure regulator Tue May 31, 2016 9:25 am

Holister

Holister
Life time member
Life time member
Injectors rely on a constant pressure to deliver the correct amount of fuel. When the vacuum increases in the intake manifold under accelleration, the flow of fuel will increase due to the greater pressure differential between the fuel rail and the injector nozzle. The vacuum tube relays this change in pressure to the FPR which then regulates the fuel pressure to maintai the correct flow thru the injectors. If the tube collapses/kinks or is disconnected, the FPR won't be able to adjust the fuel pressure and the mix will become very rich when accellerating.


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fuel pressure regulator Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

5Back to top Go down   Fuel pressure regulator Empty Re: Fuel pressure regulator Tue May 31, 2016 12:01 pm

charlie99

charlie99
VIP
VIP
@Gauntlett wrote:Am I to assume from that, that the fuel pressure is reduced slightly under maximum vaccum.

yes that is correct

the vacuum at the throttle body butterflies take off point reduces as the throttle is opened

if you watch the fuel pressure through the fpr  it pulses to a lower average value at idle  from a static 2.5bar (vacuum line removed )


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFuel pressure regulator Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

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