Fuel tank not running empty

glennis

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Hi chaps,

I seem to have a fuel gauge/ fuel pickup problem on my 2006 R1200 GSA. I'm currently in Thailand having travelled from London and about 2 weeks ago I noticed my fuel gauge was dropping considerably quicker than usual. I tend to get 350-400mls per tank (34ltr) but now am only getting 220-240 before the gauge is reading empty. This has happened on the last 4 tanks of fuel but each time only 20 or so litres goes in. So today I decided to ignore the fuel gauge and continue riding thinking that the fuel gauge must be fecked. After 20mls or so I ran out of fuel (don't worry I had a spare litre in a water bottle) I filled up at the next petrol station and 25 litres when in. WTF

Before I run off to the BMW dealership in Bangkok just wanted to find out if anyone else has had similar issues?

Cheers
 
Poor quality fuel could do that, also altitude (though I doubt that's an issue in Thailand).
 
Is it possible that kids have been tampering with your bike - putting stuff in the petrol tank? From your description it sounds as though something foreign is occupying 14 litres of space in your tank....
 
When it runs down, try opening the filler cap and sloshing the fuel (shake it side to side) and listen to hear how empty the tank actually is.

When was the tank last removed? I haven't got an adventure, but I think that there should be a quick release connector on the link pipe that joins the 2 lobes together. The QR on the link pipe might not have been done up, leaving the LH lobe full (as mentioned above).
 
There's a long thread on ADV Rider from someone with the same problem, the fuel wasn't being transferred from the RHS of the tank to the left if I remember correctly, the last time I looked it was unresolved, the BMW dealer couldn't cure it.
 
IIRC, I think at one point the guy on ADV was laying the bike on its side to get fuel over to the other side.
 
Do a Quick search here for 'Jet suction pump'

AFAIK, there is NOT a link pipe between the lobes on the 12, there's just the jet pump linkage......if the jet pump has packed up or the pipe it squirts fuel into the other lobe is blocked (or even the jet pump pickup blocked), as said above, you'll still have a lobe full of petrol that the electric pump can't 'get to', so you run out, even though you have 10 litres in the other lobe IYSWIM.

Either that or just lay the bike down on the LHS to transfer fuel over :nenau
 
Ok, so I have an update on this. After travelling through Cambodia, Vietnam and Laos I am back in Bangkok and have finally taken my bike to a BMW dealership here. The mechanic initially could not find any reason for fuel not transferring from the right side of tank to the left. Finally he swapped out the FUEL PUMP CONTROLLER and presto, problem solved, well almost!

So this is my understanding of how the fuel system works. The ECU sends a voltage reference signal to the fuel pump control module which is proportional to the amount of fuel required by the engine. The fuel pump controller then drives the fuel pump which picks up fuel from the left lobe of the tank and pumps it to the fuel pressure regulator. The regulator has two outputs, one goes to the fuel injectors, and the other returns the overflow to the right lobe of the tank. Fuel is moved from the right lobe to the left lobe of the tank by a sucking jet pump that operates on the pressure returning the fuel pressure regulator. If pressure returning from the fuel pressure regulator is not sufficient the sucking jet pump fails to operate.

The mechanic initially replaced the fuel pump controller with the new black version. This version is apparently more reliable that the older silver controller. The strange thing was with the new black controller installed the pump did not work at ALL. He then installed a silver controller from another 2007 GSA and everything worked fine. So the problem now is trying to find a new silver controller, but as I understand it BMW no longer produce this version.

On another note, I got my hands on a failed fuel pump controller and thought I would rig up a bypass cable. I connected it directly to the battery but nothing happened. I could not hear the pump motor running. I plugged the working FPC back in and turned the key on and I could hear the motor. So I tried the bypass cable again. Nothing happened.

I then started thinking that there might be another reason why the new black FPC did not work. Perhaps the same reason why the bypass cable does not work.

The BMW mechanic has no idea why the black FPC or the bypass cable does not work.

Any ideas?

Cheers,
Glenn
 
ihandyman247 said:
I think that he ask's a good question ! I use to have it on my old 1150:nenau
Click to expand...

Indeed it is a great question. Why has bumwee designed and installed an expensive, complex arrangement that is doomed to failure - as the OP has discovered - when a simple, cheap and foolproof link pipe would have sufficed?

A case of the lunatics running the asylum. I meet it regularly at work.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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