Low fuel tank capacity

[RickSkye]

Hi. I have bought a 2009 r1200 gs.
It will only take 18 l, even after its run out of fuel. Tried a couple of times. Its under the approved bike warrantee.
Is this a fault?
I don't mind taking it to the dealer but I would like to be certain its a fault, in case he tries to fob me off.
I have read loads on here, lots on the GSA but can't seem to get a definitive answer for the GS.

Thanks in advance

Rick

 

[Bendy toy]

Its likely to be either the fuel pump controller or maybe the fuel pump. The tank uses an ejector on the fuel return line to suck fuel from the right hand side. If the fuel flow is low, that ejector (BMW call it sucking jet pump) wont extract the fuel so you run out with a few litres still in the tank.

It would make a handy reserve but lets not get into that.

 

[Kenny Rodkiss]

I think this was eventually put down to a dodgy fuel pump.
If there is insufficient output this in turn reduces the return flow, which goes to the sucking jet pump, which transfers fuel from the right side over to the left, where the fuel pump is.
A poor return flow means the sucking jet pump won't work so you left with 4 ish litres on the wrong side of the tank.

 

[RickSkye]

Thanks guys.
I will get down to the dealer

 

[Wreford Miles]

I'd carry a can and run it out again and give them very specific facts.

It ran out I put exactly 5 Lt in
I rode it 6 miles to a garage
I brimmed it (and made sure it was brimmed) and it took, I'm guessing for you exactly c13 litres
Etc...

When my GSA did it I was able to tell them it only took 29liters, doing this removes the teeth sucking alternative opinions.

It will be the sucking pump related. But I think the sucking pumps ability can be defeated by very spirited riding at the time it needs to be using (sucking) the last of the fuel on the other side which is another reason to do a run out test

 

[Bendy toy]

When my GSA is running out of fuel I get a few random hiccups up to 10 miles before it finally croaks to a stop. It rarely gets serious beans because the roads are too narrow/clogged for that. The GSA tank has deeper wells each side so the jet pump has to work harder and when its really low probably pulls some air.

If the fuel pump controller workaround solves the problem you'll need a new controller. what colour controller do you have?

Google "UKGSer fuel pump controller bypass"
Here's one http://www.ukgser.com/forums/showthread.php/143272-Fuel-pump-controller-workaround

 

[Bendy toy]

Reserve fuel supply

Running out of fuel is a level gauge issue and to a lesser extent a pump controller fault. But for many it's crying out for a fuel tap to solve the problem of transferring fuel from the right side to the left. It should work well on the GS with about 5 litres of "reserve". The GSA with its deeper tank sides will end up with more reserve than necessary.

It will need a fuel hose and fuel tap to link the tank bottoms under the frame so not a dead simple fix.
I can't believe Im the first to think of this so hopefully those who have done it, will have already sussed the problems or maybe found it's a no hope.

 

[Greenman14]

Running out of fuel is a level gauge issue and to a lesser extent a pump controller fault. But for many it's crying out for a fuel tap to solve the problem of transferring fuel from the right side to the left. It should work well on the GS with about 5 litres of "reserve". The GSA with its deeper tank sides will end up with more reserve than necessary.

It will need a fuel hose and fuel tap to link the tank bottoms under the frame so not a dead simple fix.
I can't believe Im the first to think of this so hopefully those who have done it, will have already sussed the problems or maybe found it's a no hope.

Good idea Bendy, can't believe someone hasn't done this before. Though how to reliably install an extra fuel connection without internal access to the tank seems a likely problem, plastic welding? Thing is if the new connection ever failed there would be a proper mess, possible fire, and maybe a long walk home.

 

[Pukmeister]

Does it have a rubber neck liner inside the fuel tank?

Some folks on the early R1200GS back in 2004 had trouble filling the tank enough. Many solved this by simply removing the rubber filler neck liner by ripping it out with their fingers (myself included), others went as far as drilling vent holes in the skin of the metal filler neck to allow air to escape when filling and thus get a full tank instead of a layer of trapped air in the top of the tank. Try searching for fuel tank mod for the 1200 GS and see if you can find any old info that might shed some light on this, such as:

http://www.ukgser.com/forums/showthread.php/23544-Fuel-filling-problem?s=

Perhaps your tank is doing something similar to the early bikes, preventing it from fully filling up when you refuel ? I'm not suggesting you drill your fuel tank but your filling with 18 litres issue could be due to a similar problem with trapped air/tank capacity.

I take it you have tried refuelling with the bike on the centre stand to see how much it takes with the bike level, and not just refuelled on the side stand ??

 

[RickSkye]

Reply to all.
I have done 2 runout tests with fuel can, same answer.
I have got the exact details re fuel, miles ect, for both times, so thats good.
Always filled on the center stand.
Riding around in a 40 zone so not going too fast.

I had a honda 250, maaany years ago. The equalisation pipe came off and showered my legs with fuel.
Luckily I stopped next to a stream, pulled the tank off and
dived in the stream. Very very lucky no fire.

 

[Belizibub]

All though my issue seems the same it was a 2013 GSA, very near to the reserve the bike would cut out as if no fuel. Opening the fuel cap and swishing the bike left to right and closing it up would start the nike and enable me to get to a station, where it would only take 28 ltrs.
Dealer swapped out the reserve fuel pump and checked al hoses to no change. Ended up with right pump and al new electrics for the tank before the issue was fixed.
BMW Tech said it was a lack of pressure in the tank that stopped the reserve being picked up.

 

[Bendy toy]

Good idea Bendy, can't believe someone hasn't done this before. Though how to reliably install an extra fuel connection without internal access to the tank seems a likely problem, plastic welding? Thing is if the new connection ever failed there would be a proper mess, possible fire, and maybe a long walk home.

First off - There is no issue, when the fuel pump controller is working normally.

Above is exactly why I've not taken the idea further, but I believe it would give a useful reserve fuel capacity which these bikes do not have as standard.

Risky? Many British bikes had two fuel taps - one on each side of the frame. One tap was used to mostly empty the tank then the other would empty the opposite side giving a reserve capacity with minimal effort. Later bikes used a single tap with a stand tube. Normal use took fuel via the tube. When that ran dry turn the tap to switch to the tank bottom outlet.

I believe the GS/GSA is doable with bolt-on hose barbs. The bike covers at the front allow internal access to the tank. Bolt-on hose barbs can be got with an internal flange O ring and retaining nut on the outside. Put one on each side and run a fuel hose tube under the tank. It would ideally need a QD connector for fuel tank removal. But we have them on the fuel pump so not biggie there. That does not solve the serve tank issue so would need a fuel tap to open the cross connection when the main tank runs dry. Lots of issues to consider including removal of the internal jet pump pipes..

 

[RickSkye]

So, been to BMW Inverness and they have replaced a fuel sensor. Don't know yet if that has fixed it, but i can't see the logic if it has.

 

[Kenny Rodkiss]

Won't fix your problem which is fuel not being transferred from the right side to the left.
The sensor is in the same side as the pump ( on a gsa )and will read empty when the left side runs dry but will still have a few litres in the right side which not been transferred.

 

[Bendy toy]

Who was the fuel sensor last changed? It's possible the internal pipes have been disturbed so that fuel on the right is not being sucked across by the venturi (jet) pump.

The less likely option is a fault with the fuel pump or its not been correctly put back into the tank.

 

[stanley]

We are talking about a gs here... I thought it was only the gsa that has the sucker jet pump?

Sent from my GT-I9505 using Tapatalk

 

[Bendy toy]

I thought they all did. But if the GS does not have the jet pump it might be a fuel pump issue.

The pump hangs under its mounting flange on three quite bouncy rubber mounts. They are not difficult to dislodge so maybe the pump has fallen off.

 

[Wreford Miles]

So, been to BMW Inverness and they have replaced a fuel sensor. Don't know yet if that has fixed it, but i can't see the logic if it has.

I had this palaver - they don't seem to get the logic that the bike has fuel in it but it's not reaching the engine.

They seem to have a mental block that says if the engine is not getting fuel, that means it's run out and if that's the case why did it run out when you thought it had fuel in it - it must be sensors etc...

I had to repeat several times 'be in no doubt the bike had fuel in it, so find a fault in why it's not getting to the engine not why I may have mistakenly run it dry'

 

[RickSkye]

Well, just done 241 miles on a tankfull (183 before) and filled it up with the best part of 21 litres. Go figure.
The fuel sensor must do a lot more than i think.

 

[Bendy toy]

Being close to empty, I recently opened up both tank access covers (08 GSA). There was maybe three litres in the left hand side. The right side was totally dry. I guess it should be as the sucking jet pump should be pulling fuel across.

Well, just done 241 miles on a tankfull (183 before) and filled it up with the best part of 21 litres. Go figure.
The fuel sensor must do a lot more than i think.

Which fuel sensor have they changed? Fuel strip, float gauge or something else.