Fuel lines on right side of GSA tank

TLSgazza

Well-known member
UKGSer Subscriber
Joined
Dec 30, 2008
Messages
4,619
Reaction score
770
Location
northants
Sorry for the long thread. But a bit of history might help.
My bike went in to a main dealer 3 weeks ago to get the fuel strip changed.
They failed to get a new strip to calibrate to the bike after numerous attempts.
They then told me the ECU is probably faulty and needs changing. 😳
I declined this kind offer understandably.
Anyway when I left with the old fuel strip reinstalled the warning light was no longer on and the guage is showing three quarters of a tank constantly. With a range varying between 370-410 miles now. I'm assuming the many attempts to calibrate a new strip has buggered the calibration of my old one.
The old strip is now, I would say, communicating with my ECU.
Fast forward 3 weeks and whilst giving the bike a clean today I noticed none of the pipes on the right side of the tank are connected to the tank. 😱
I have ridden about 600 miles in that time with no obvious problems though I did on occasion smell fuel whilst riding.
Is the one with the quick release coupling the fuel return hose? And the other rubber hoses just breathers?
I'm really confused by this as like I said I've ridden hundreds of miles like this, fuel consumption seems as per normal.
I have now connected them all though I'm not sure which way round to connect the 2 rubber hoses or if it even matters.
Any help from anyone would be nice.
IMG20241117120926.jpgIMG20241117120922.jpgIMG20241117121421.jpg
 
Looking at your last photo, the left hand connection is the tank overflow, the middle one is the tank breather. The right hand (quick-disconnect) connection is a return line to the tank but thankfully that connector has a valve in it which closes when the connector is separated.

You would only notice the effect of the disconnected return pipe if you run the tank low as this feed provides the drive for the venturi pump which moves fuel from the bottom of the right hand side of the tank to the left where the main pump is.
 
Looking at your last photo, the left hand connection is the tank overflow, the middle one is the tank breather. The right hand (quick-disconnect) connection is a return line to the tank but thankfully that connector has a valve in it which closes when the connector is separated.

You would only notice the effect of the disconnected return pipe if you run the tank low as this feed provides the drive for the venturi pump which moves fuel from the bottom of the right hand side of the tank to the left where the main pump is.
Thank you for that. I did wonder How I've managed to use it for the last 4weeks without them connected. Does it matter which way round the 2 push on black pipes go?
 
According to the BMW manual (RSD), the pipe with the white mark is supposed to be connected to the overflow. Looking at your pictures, I'd guess that's the one with the white inner (left hand pipe in pic#2).
Usual caution applies with the Q-D connector to be careful not to snag the o-ring when mating the connector.
 
The quick disconnect as stated is the return from the fuel pressure regulator which operates the venturi pump. but with it disconnected it will put the fuel pressure sky high. only limited by the relief valve in the pump.
This can be as high as double the recommended pressure.
The fuel pressure may be low enough due to a weak pump for this not to be a problem, if this is the case and the pump is that bad the venturi /transfer pump will not work very well.
 
The quick disconnect as stated is the return from the fuel pressure regulator which operates the venturi pump. but with it disconnected it will put the fuel pressure sky high. only limited by the relief valve in the pump.
This can be as high as double the recommended pressure.
The fuel pressure may be low enough due to a weak pump for this not to be a problem, if this is the case and the pump is that bad the venturi /transfer pump will not work very well.
Thank you. I may have got away with it but I will be having a word with the dealer tomorrow. This Is quite unacceptable.
It does seem to be running ok.
 


Back
Top Bottom