2004 fuel flow issues


Hey everyone,

I bought an '04 Busa earlier in the year with 75K miles on it to use as my street bike. It needed some love at first and wouldn't rev past 8K @ WOT. I measured the fuel flow per the service manual and got 200ml/30sec.
So I have since:
-Replaced the injectors with some fresh RC-cleaned OEMs
-Replaced the ecu with my street flashed unit
-Cleaned the fuel line and rail
-Replaced the fuel pump with a known good pump from an '07 with a clean strainer
-Cleaned and lubed the FPR, and zip-tied it to the pump assembly for added insurance (press. measured at 48psi)
-Cleaned and inspected the fuel pump assembly housing.
I've now got the flow at 600ml/30sec which is still half of where it should be (1,200ml/30sec). It finally revs to the limiter, but is definitely losing power at the top end (probably lean).

Any ideas on what still might be the problem? My next move is to just buy a Walbro / Bosch intank pump, but trying to keep the costs down on this bike so I have more funds for the race bike.

Also, I noticed that the Walbro pump specifically for this bike requires some "modification" to make it work right. What modifications are necessary for this?

Somebody will help you out in time...as far as the pump and the mech issues with the fuel system...you just have to outsmart it...it seems like you have tried several things so far
you cleaned the fuel hoses.........would be better to replace them as they dose after a few years and collapse shut under suction of the pump at high revs.
I know what you're talking about with the 99-00 hoses, but this is an '04 in-tank pump. I only have one hose, and it's always pressurized.
Sounds just like a plugged fuel filter!
Either replace for over $250 or try this,,

Linky, https://www.hayabusa.org/forum/maintenance-do-yourself/175027-fuel-filter-mod.html

Yea there seems to be a ton of high mileage Busas these days. I agree that this may be the issue. After this you have nothing unless you have a plugged fuel rail. I just went through mine completely, removed the stock filter and resealed it, replaced the pump with an intank Bosch and I also modded the fuel rail too. Better than new.
YES!!!!! that was it. Flowing at >1200ml/30 sec. Thanks Gixxer, she's a rocket now. And just to confirm, I rechecked the factory service manual and there is no indication that there is a fuel filter in that housing. So for those searching this problem in the future, just drill out the fuel outlet in the black housing and install an external fuel filter in the fuel line.

Done and done. Let's ride!!!:brave:
Glad it worked!
The thanks belongs to Chrisjp, he found the fix on the VStrom site!