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Old 08-25-2010, 08:29 PM   #1
colewj OP
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Joined: Jul 2010
Oddometer: 17
R1150R Low Fuel Light Problem....Please Help

In short the problem is:

* "The bike" went into the shop because it's engine had stopped.
* Hose from fuel pump was reconnected
* "The bike now runs fine BUT the low fuel light is now constantly 'ON'.

I'm hoping the collective knowledge of all the riders on the forum will have a solution as the constant orange light is getting old.
Here's what happened:
Long Version:
The patient, "The bike", is a 2003 R1150R with just under 18,950 on the clock.
Back at the end of June the following services were done: Fuel filter,Rear brakes,Valves adjusted and injectors balanced,Fluids (all) changed,Tires replaced, New York State Inspection.
Life is Good
Two weeks later "The bike" quit on my way to work.
The engine just quit. Period. It felt like hitting the kill switch or turning off the ignition.
Once I got to the side of the road and began to figure out what the problem was the only thing out of the ordinary was a strange noise from the fuel pump and the fact that "The bike" would not start.
Just in case "The bike" was out of gas and the low fuel light had failed, my daughter, who came to my aid, brought gas which I added.I didn't think this was the case because when "The bike" quit it was immediate. It was not the same sensation as running out of gas which happened a few years ago.
I went back in the evening with a trailer, picked up "The bike" and took it to the shop.
Good news:
The word was that "The bike" had quit because the hose from the fuel pump to the fuel filter had come off at the discharge end of the pump. That was also the reason for the strange noise from the fuel pump.
This end of the hose had not been removed from the pump two weeks previously when the fuel filter was replaced.
The hose was securely put back where it belongs (and Life is Good).
Not !
Bad news:
The problem, I was told, was that now the low fuel light had come on and would not go out.
The shop had removed and replaced the tank 3 or 4 times and they could not get the light to go out.
They asked if the low fuel light had been on when "The bike" quit. It had not. In fact gas was added after "The bike " quit.
The low fuel light has functioned normally for the approx. 18,800 miles that I've owned "The bike".
All wires were checked. The underside of the tank and flange were checked for damage that may have occurred while removing/replacing the tank etc. and no damage was detected.
They plan to look into what may be another cause and get back to me, but they figure that the low fuel sending unit is bad.
I've been looking at the orange light ever since.
To the best of my knowledge the low fuel sending unit is not available separately. From BMW it's $400 +, from The Boneyard it's $200+ since I'll have to buy the whole flange and fuel pump assembly.
I found one that a fellow member had posted for sale which had a bad flange but someone else had been interested and he was waiting for payment.Eventually the guy came up with the $40.The member said he would try to contact the guy to see if (hopefully) the guy does not need the low fuel sending unit so there's still hope from that source.(I'm keeping my fingers crossed, consulting the spirits, and have retained the services of a Voodoo witch doctor.)
I've had suggestions that I pull the relay, pull the bulb, or tape over the bulb and just use the odometer
I'm fine with using the odometer but I'd really like to get the cause taken care of.
I'll be most grateful for some help.
Thanks, Bill
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Old 08-26-2010, 05:21 PM   #2
Red Roadster
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Location: Meeteetse, WY
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I believe there is an arm with a float inside the tank. If this arm is in contact with hoses or the pump, it will keep the light turned on. Remove the tank and plate to check it.
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Old 08-26-2010, 05:48 PM   #3
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That would be my guess. The goof who re-installed the mounting plate that carries all the hoses, filter, fuel pump and sensor electrics either bent or jammed the float arm. It is also possible to install the plate wrong (i.e., twisted from the proper location.
Take it back to a tech you trust.
The Red Rocks
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Old 08-26-2010, 06:51 PM   #4
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R1150R has a float inside a small white can. No float on an arm those are for bike with RIDs. see:
Could be a wire was broken when the work was done.
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Old 08-26-2010, 07:15 PM   #5
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Location: Northwest PA
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Put a piece of electrical tape over the light and just pay attention to the trip meter.
2007 R1200GS
Member in good standing, Mud and Blood Race Team: Annoying the Neighbors Since 1973
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Old 08-27-2010, 09:05 AM   #6
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Joined: Jun 2004
Location: Scottsdale AZ..
Oddometer: 3,498
same problem

I have the same problem on my R1100RS. Constant orange light.
Master mechanic.. has worked on it.. and taken the tank off
a few times.. but it stays on.

Looking for a new fuel pump and sensors for the tank to see if that will
fix it. I keep an eye my miles all the time.
BMWMOA 82741 ABC 8418
75 R90S , 77 R100 RS,88 R100GS ,94 R1100RS (Aragorn) 2k 1150GS DMC sidecar,
Rosso Mandello V11 , 2014 R nine T
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Old 01-27-2015, 12:07 PM   #7
Joined: Jan 2015
Oddometer: 1
Inverted fuel light explained

This post is from a long time ago, but I recently encountered this issue and fixed it.

Under the fuel plate of the tank, there is a little white plastic cylinder with two wires coming out of it. This is the low fuel level sensor. It is not sold separately as far as I know. There is a cap on the end that pops off like a film canister. This unit can be removed from the fuel plate. First, bend it upwards and outwards on its arm. Second, there are ridges that hook into the plastic on the cylinder to keep it in place -- Open those up and pull it out.

Inside, you'll find a black donut-shaped float that slides up and down a cylindrical rail in the center. When your fuel level is high, it floats to the top (side opposite from the wires). When the fuel level is low, it's allowed to drop all of the way to the bottom (wire side). You can just manipulate this with gravity to demonstrate its functionality. If it's working correctly, continuity occurs only on the low side.

The float is magnetic and when it gets to the low side, it completes a circuit with the two wires via a reed switch (A small glass capsule with contacts that are almost touching, when a magnetic is introduced, they close). The wires are soldered to each side of that reed switch.

One common failure is that the reed switch breaks, and there will be no low fuel light at all. This was my case, and you can solder out the wires and wire in a new reed switch. The reed switch positioning is important, and it should be fairly close to the low side to work effectively. Test with gravity.

But if you're getting inverted behavior, then your reed switch has managed to move itself to the high side of the cylinder, which causes the magnet in the float to cause continuity when the float is high and break continuity when low. To fix this, you need to move that reed switch into the correct location. If it were me, I'd just solder the whole assembly out and try to reposition it from there.

One final note: To make it easier, I just wired one side through the lid so that one wire went in the bottom, reed switch in the middle, and the other wire out of the top. This has worked fine. I melted the lid's plastic into the top wire to keep it in position and used a nylon zip tie to secure it to the plastic cylinder housing.

Hope this helps someone.
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