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Bike Fuel Pump
PaulYDP - 25/3/09 at 12:05 PM

Hi guys,

I had my car away yesterday getting the dynojet kit fitted and it set up on the rollers. However it appears I have an issue with the fuel pump not being able to supply enough fuel at peak power and it is running lean. Going up a jet size made no difference so it must be the pump.

I have a zx9r engine and am using the bike pump for the engine, the tuner yesterday said that the pump is gravity fed and should be below the level of the tank which mine isn't - can someone that is using a bike pump tell me where they have mounted it. Have you mounted it at the back beside the tank or at the front beside the engine - mine is at the front of the car and mounted about level with the top rail of the chassis.

Any help much appreciated!

Thanks,
Paul

Hellfire - 25/3/09 at 12:12 PM

IIRC, motorbike fuel pumps are better at pushing fuel than pulling it and are best mounted at the rear, below or level with the bottom of the fuel tank.

Phil

coozer - 25/3/09 at 12:16 PM

Mine is at the back on the bottom chassis rail, gravity feeds the pump before its pushed to the front.

PaulYDP - 25/3/09 at 12:24 PM

Cheers guys, that's exactly what I thought I was going to have to do after talking to the guy yesterday, looks like that is my task for the weekend then!!

YQUSTA - 25/3/09 at 12:28 PM

mine is at the front like yours and is a ZX9R too.

This is how it came when i bought the car

PaulYDP - 25/3/09 at 12:32 PM

Mine does work at the front, but it was leaning out too much between 7k - 11k rpm and it is because the supply of fuel isn't enough - i'm not sure how much you would notice it on the road though.

DarrenW - 25/3/09 at 12:42 PM

Mine is at back near bottom of tank.

Paul TigerB6 - 25/3/09 at 02:57 PM

quote:
Originally posted by PaulYDP
Mine does work at the front, but it was leaning out too much between 7k - 11k rpm and it is because the supply of fuel isn't enough - i'm not sure how much you would notice it on the road though.


As stated, bike pumps work better pushing fuel so really should be repositioned to the back. If the mixture is leaning out then you could be risking your engine (holed piston etc) with sustained high revs from a track day etc. You will also be losing power.

I'd say definately reposition the pump - you will feel better for doing it i'm sure.

[Edited on 25/3/09 by Paul TigerB6]

idl1975 - 25/3/09 at 03:14 PM

quote:
Originally posted by PaulYDP
Cheers guys, that's exactly what I thought I was going to have to do after talking to the guy yesterday, looks like that is my task for the weekend then!!


Same as the other guy - it's on the inside of a lower frame rail right at the back, under and inboard of the tank. Standard '893 blade fuel pump.

asn163 - 25/3/09 at 03:24 PM

Does this help?

Courtesy of Mad Dave, his old zx9 powered Indy.


Feb 05
Feb 05


My set up is similar but my tank outlet is at the bottom.

HTH

Simon

[Edited on 25/3/09 by asn163]

PaulYDP - 25/3/09 at 04:34 PM

quote:
Originally posted by Paul TigerB6
quote:
Originally posted by PaulYDP
Mine does work at the front, but it was leaning out too much between 7k - 11k rpm and it is because the supply of fuel isn't enough - i'm not sure how much you would notice it on the road though.


As stated, bike pumps work better pushing fuel so really should be repositioned to the back. If the mixture is leaning out then you could be risking your engine (holed piston etc) with sustained high revs from a track day etc. You will also be losing power.

I'd say definately reposition the pump - you will feel better for doing it i'm sure.

[Edited on 25/3/09 by Paul TigerB6]


Cheers Paul, I will definitely be repositioning the pump! I am losing power thats for sure - have 120bhp @ the wheels but that was only a 1bhp increase going up a jet size, it should have been approx a 5% increase if the air/fuel ratio was correct! (ps. I haven't forgotten about taking the measurements for you, I should have them for the weekend!!)

Thanks for the picture, I think thats what I will do!

Paul TigerB6 - 25/3/09 at 05:08 PM

quote:
Originally posted by PaulYDP

Cheers Paul, I will definitely be repositioning the pump! I am losing power thats for sure - have 120bhp @ the wheels but that was only a 1bhp increase going up a jet size, it should have been approx a 5% increase if the air/fuel ratio was correct! (ps. I haven't forgotten about taking the measurements for you, I should have them for the weekend!!)



Cheers Paul. No rush at all for the measurements. At the rate i am going, we will be looking at the successor to IVA by the time i get my car built!! Still looking for a new job here before i can carry on with my car. Who's dumb idea was it to get into Financial Services - still, just applied for a good job locally today and one last week so fingers crossed.

PaulYDP - 25/3/09 at 05:18 PM

Fingers crossed on a new job for sure!! It really is hard times out there at the minute. I will get the measurements asap for you anyway, it'll give you something else to think about!