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Max fuel pressure for 2006 Busa?
Northpole - 21/8/12 at 04:59 PM

I did start with 3.9 bar fuel pressure using a Fuel pump from Mercedes Benz.

That turned out to be to low when running above 7000 rpm, so I increased it to 4 bar.
It was better but still on high rev the motor does not seems to run perfectly.

So my question is, how high can I go in Fuel pressure?

I am running a standard 2006 Hayabusa motor.

Thanks

danny keenan - 21/8/12 at 05:11 PM

The standard pressure is 3.2 bar you need to turn it down it should run much better then.

Thanks Danny

Northpole - 21/8/12 at 05:23 PM

quote:
Originally posted by danny keenan
The standard pressure is 3.2 bar you need to turn it down it should run much better then.

Thanks Danny


Hi Danny thanks for your comment.
The thing is, when running on 3.9 bar above 6000 rpm the motor does not respond, it stops. When increasing the pressure up to 4 bars it went up to appr 8000 rpm.
But I could try to go down, but I am afraid it will not run well, but again I dont know.
sigurjon

SeaBass - 21/8/12 at 05:27 PM

Turning up the pressure regulator is not a solution to your problem... think of it as a variable restriction that maintains a set pressure in the fuel rail. If the pressure drops below the "regulated" pressure the regulator is pretty much closed completely but the pump is not able to provide more.

Jon Ison - 21/8/12 at 05:32 PM

Sounds like a flow problem rather than pressure, any pressure increase over stock will cause over fueling low down the rev range, not something you want.

It's bot lack of pressure holding back the revs but lack of flow.

Northpole - 21/8/12 at 05:46 PM

Ok so maybe this problem could be caused by the fuel pump? It is a second hand one so it could be a bad one?

Old and tired fuel pump, can it not fail on load?

Northpole - 21/8/12 at 07:12 PM

OBS!
Sorry guys, I did run at first with 2.9 bar fuel pressure, not 3.9 bar.

Northpole - 21/8/12 at 07:16 PM

quote:
Originally posted by danny keenan
The standard pressure is 3.2 bar you need to turn it down it should run much better then.

Thanks Danny


OBS
I did write 3.9 bar but I did run it on 2.9 bar in the beginning, sorry...

sickbag - 22/8/12 at 01:54 PM

Where is the fuel pump located, is it at the rear of the car? It could be suffering a low flow rate due to restrictions in the pipe to the engine. In which case you could fit wider bore piping, or fit a swirl pot and a low pressure feed pump in the engine bay.

Northpole - 22/8/12 at 04:07 PM

quote:
Originally posted by sickbag
Where is the fuel pump located, is it at the rear of the car? It could be suffering a low flow rate due to restrictions in the pipe to the engine. In which case you could fit wider bore piping, or fit a swirl pot and a low pressure feed pump in the engine bay.


Thanks for your comment/help.
Yes the fuel pump is in the rear of the car, close to the fuel tank and is connected to new fuel filter.
I am betting on the fuel pump, and have ordered a new Walbro 255 inline fuel pump.
Hopefully that will solve this problem.

What are you using for pipe lines? 10 mm 8 mm or? I am running on a 10 mm inside diameter for my fuel pipes.

richard thomas - 22/8/12 at 06:39 PM

8mm is fine, I am using a sierra EFi fuel pump - no probs....swirl pot in engine bay, 43 psi (i think)