Fuel Pressure




65Cobra

Registered
My understanding is the fuel pressure at idle should be 43 psi, but is that with or without the vacuum line connected to the regulator? If I adjust the fuel pressure to 42-43 psi without the vacuum line connected (and plugged), once I attach the vacuum line it drops to about 37-38 psi. Not sure which is correct. Thanks.
 

cdhoroho

Registered
there should be a check valve inline so that the fmu doesnt see vac but does see boost

on a standard regulator it is different you let a standard 1:1 see vac
 

65Cobra

Registered
Okay, I have to admit I was trying to keep this easy, but you just had to go there didn't you Pinky. :laugh:

I have a BEGI 30 Series regulator (2035) which has an additional bottom chamber that is a 1:1 regulator. This model incorporates both a R/R regulator and a 1:1 regulator into a single unit. As a result, the hose from the throttle body goes to a Tee fitting, with one line going to the R/R chamber like all their models, and the other line going to the 1:1 chamber.

I know you and I discussed the check valve before but apparently installing the check valve inline before the R/R regulator is for users who what to use the BEGI 20 Series regulators (i.e. 2025) without a 1:1 regulator, and it does work so your advice is solid. But if someone adds a 1:1 regulator, or like my case, uses a BEGI 30 Series regulator, then the check valve has to be moved from it's inline location back to the R/R Needle Valve outlet or it defeates the purpose of having a 1:1 regulator.

When I purchased the 2035, I thought a 1:1 regulator was always required, but obviously that's not the case. At first I was slightly disappointed, but I've read where using a 1:1 regulator with the BEGI is supposed to steady the base fuel pressure and create a more accurate fuel curve during the transition from vacuum to boost. So, with that in mind, I feel better, but I also have to leave the check valve at the Needle Valve outlet.

After I posted this topic my brain's time delay finally kicked in and told me to check the Service Manual, duh... which I did and it says "the fuel pressure regulator... keeps the fuel pressure applied to the injector at... 43 psi higher than that in the throttle body at all times" Also in the part that explains how to check the pressure at the regulator says nothing about disconnecting the vacuum hose but still says it should be 43 psi.

So I guess I answered my own question and have to make an adjustment so it's 43 psi with vauum. But if you, or anyone else for that matter, have any other comments or opinions, please let me know because I'd be interested in hearing them. Thanks.
 

OZBooster

Registered
Interesting question because the 99-00 was vac referenced but the 01 + was intank and not referenced, so if your bike is 01+ you may still be better running a check valve or spend more time on the dyno doing part throttle stuff ????
 

65Cobra

Registered
I didn't realize there was a difference OZ so that's a good point. I do have a 99 with an external fuel pump and regulator that's vacuum referenced. I puchased the manual back then so it only addresses that year model and I've only recently been finding out about the differences with the 2001 and newer models. I'll readjust the fuel pressure tonight for 43psi with vacuum, then move on from there. Actually this is good because the new logs I make afterwards might come out a little better. Having this forum is a blessing. Thanks to you and Pinky, and everyone else, I'm feeling better about things as I go on. :cheerleader: Okay, maybe not that happy.
 
Thread starter Similar threads Forum Replies Date
mike miller Fuel pressure issue Turbo 5
S Gen one fuel pressure General Bike Related Topics 8
D External Fuel Pressure Regulator Busa Mods 1
V fuel pressure under boost? Turbo 6
C Fuel pressure questions Gen II Busa Information 7
GXR1147 Base fuel pressure slowly drops while riding Turbo 98
Narcissus Fuel Pressure Regulator and Pump Testing Busa problems 2
Jake whitebird Fuel Pressure On Turbo Build Turbo 17
B Fuel Pressure Regulator Return Line Busa Mods 1
K Fuel Pressure Drops When The Fan Kicks Turbo 13
jstdoit95 Where to find a fuel pressure regulator? Busa problems 5
I afr, boost, fuel pressure gauges?? Turbo 6
Quiksilver dropping fuel pressure after priming. Turbo 4
HayabusaPilot Turbo fuel pump/pressure regulator question Turbo 12
rob702 Fuel system not holding pressure Engine and Performance mods 4
ColdBusa Monitoring Fuel Pressure Turbo 5
S Re: fuel pressure regulator question Maintenance and Do-It-Yourself 2
jermzfree Fuel pressure question Turbo 10
cyborgbusa Fuel Pressure? Busa problems 2
N Fuel pressure fluctuations? Super Chargers 2
H 40 psi fuel pressure is waaay too much! Turbo 7
E fuel pump pressure Busa Mods 3
N Fuel pressure under boost Turbo 24
N rising rate fuel pressure regulator Turbo 1
B i think i have a fuel pressure problem Turbo 4
quantumracer Fuel Rail Pressure Gen II Busa Information 2
G Fuel Pressure port size Turbo 2
6 Fuel Pressure vs A/F Ratio Turbo 6
Jimingle10 Fuel pressure pulsating badly....video attatched Busa problems 1
slatroni Fuel pressure Engine and Performance mods 5
C Fuel Pressure Fluctuations Turbo 14
S 99 Busa fuel pressure Busa problems 1
C fuel pressure Nitrous 3
B@DA$$08BUS@ Fuel Pressure on 08 Gen II Busa Information 7
texas-buzzard high fuel pressure Turbo 21
M Fuel pressure Engine and Performance mods 2
miserycaptain 2005 Fuel Pressure Regulator? General Bike Related Topics 12
L testing fuel pressure Busa problems 0
L Fuel Pressure Tester General Bike Related Topics 1
B fuel pressure regulator and the map Turbo 2
J fuel pressure Turbo 14
N Fuel pressure? Busa problems 7
3gturbo fuel pressure issue Turbo 3
busa2001 fuel pressure at idle Turbo 0
B I need a stock fuel pressure regulator!!!!! Turbo 2
T I need a fuel pressure gauge General Bike Related Topics 1
H Fuel pressure Busa problems 3
O increasing fuel pressure Modifications & Aftermarket Equipment 2
F Raising the fuel pressure. General Discussion 18
O Fuel pressure regulator Modifications & Aftermarket Equipment 6
Similar threads




















































Latest Bikes

  • A blue bike
    2017 blue & black
    • Hayabusa Wannabe
    • Updated:
  • 2011 busa
    2011 limited edition candy sonoma red busa
    • Hetheus
    • Updated:
  • New guy here
    Hey what’s up everybody! My names Matt from Southern California. I just...
    • Los.great.beard
    • Updated:
  • My 2014 Hayabusa
    2014 Hayabusa 50th Anniversary
    • Dljat2
    • Updated:
  • Hi Everyone
    Loved
    • BirolBora
    • Updated:

Forum statistics

Threads
174,206
Messages
3,120,125
Members
48,300
Latest member
NorthernViking
Top