Fuel Gauge continuing problems

[JOHNF]

My 2005 bike continues to have a improperly performing fuel gauge/bike computer. This past weekend I participated in a 24 hour rally, and my results were affected by the fact the fuel gauge, low fuel light, and bc all said I was out of fuel at 175 miles (+or-), meaning more gas stops than needed.

Here is what usually happens, although there are variations, all of them bad.
I stop and fill up the bike. When I turn the key back on the bc says anywhere from 185 to 215 miles to go until empty (this should read about 275 ). I drive 10 miles and the fuel gauge is down to half (sometimes when I start the bike the fuel gauge goes right to 1/2, and I can look in the filler tube, and there is gas to the top of the tank), and miles to go may be down to 120 area.

The fuel gauge stays at 1/2 for a long time, and the total of miles to go until fuel needed + miles ridden on the tank slowly increase from the 130 mile total of above to the 175 range. (Again this total should be in the 265-280 mile range)

At about 145 riding miles the low fuel light comes on, bars appear at about 165, and fuel gauge reads empty. All indicators I am out of gas...stop for gas at about 180 miles on the trip odo and put in usually about 4.2 gallons of gas.
I am tenative about running to a higher amount using the math of MPG estimate x 6.3 gals=miles I should be able to go, because I have run out of gas way short of 240 miles on the tank, and do not want to pay $65 for a gallon of gas (I know this amount from more than one experience), and for the rally could not risk the extended lost time of running out of gas.

I have no dealer in Cinti now...this still should be a warranty issue, Tri State was familiar with their numerous failed attempts to solve the problem. BMW Motorrad is of no assistance at all ("take it to another dealer and have them look at it"). My dime or BMW's?

All right tech gurus...what would be your list of, I am going to look at this first, then second, etc. It appears I will have to make an appt at the new dealer in Cols (3 service managers in a year is not a good sign). And why is it so hard to get a service dept to tell one what steps they are going to take to investigate/solve the problem? The standard answer of, "we'll just have to get into it and see" always rubs me the wrong way...another issue.

I would even think about riding to a dealer in a 500 mile radius that has expert (not good, expert) techs and the ability to solve the problem.

Running on empty in Cincinnati, OH (even though there's still gas in the tank)

John F

[murray]

John # 1 pleasure meeting you this past weekend. Do you fill the fuel tank on the side stand, That is the only way to properly fill the tank? If filled on the center stand you may only be able to pump 4 G into her. Also try to see how many miles you get out of a tank, Run it dry. Stuff a gas can on the rear seat to refill.

[hawg]

John,
When I bought my new '04 LT, the fuel light came on at about a half tank. Dealer used the computer and reset to a point that I specified. I am sure a dealer can do the same for you.

Good luck.

[PATTERSON]

Mine is an 05, and did the same exact thing. The dealer set it so it now comes on at approx 75 miles..........

But still, the most I've ever been able to get in there is about 5.7 gallons. And that was straight upright....on the center stand. Course, both my wife and I were still sitting on it too!! :D

[mneblett]

I agree with the suggestions to frst try to have the fuel gage calibration reset by a dealer.

Your symptoms suggest that the BC is functioning properly -- it is calculating miles to go based on the (erroneous) fuel level being reported from the fuel level sensor in the tank.

The sensor is a simple float-inside-a-tube arrangement. From your description, it sounds like either: (i) the computer is calibrated such that when the float is at the top of the tube, the computer thinks the electrical resistance reported by the sensor means "1/2 full"; or (ii) the sensor is damaged (tube dented or electrical fault), causing the float to hang up or the worng electrical resistance to be reported. I believe it's much more likely a calibration issue, which can be easily addressed by a dealer's diagnostic machine.

A suggestion: Arrive at your dealer's with the fuel level about where you want it when the yellow warning light comes on. The diagnostic machine can program the warning level to whatever amount remaining you want (.5 gal, 1 gal, 2 gal., etc.) -- it can tell the bike's computer to assume that the amount currently in the tank is the appropriate level for setting off the warning.

[mpillis]

Hey John , nice to meet you today. Maybe someone else can answer this also> On a trip to Florida last year I stopped and filled up and started down the road and noticed that my guage stated that I could only go about something like 150 miles after the fillup. Stopped for a break down the road and it reset itself correctly. I remember that I saw on this site someone else mention this and whay it had happened. It was sonething I did but I cannot remember what it was. Anyone else remember what caused this temporary situation?

[tobiwan]

My 05 does the same thing. the computer counts down to where it says - - -. I fill it up with 6.3 gallons. the computer then reads 125 to empty. over time it will creap up 290 to 320. The LED indictor rises to the top, but the Miles computed lags behind. It seems to be temp. related. It has been rather cool here for the last few weeks and do not remember this being a problem last fall until it got cooler. But the problem in FL would seem to contradict this theory
Are there two sensors? one for the Visual indictor and one that the computer reads?

[mneblett]

My 05 does the same thing. the computer counts down to where it says - - -. I fill it up with 6.3 gallons. the computer then reads 125 to empty. over time it will creap up 290 to 320. The LED indictor rises to the top, but the Miles computed lags behind. It seems to be temp. related. It has been rather cool here for the last few weeks and do not remember this being a problem last fall until it got cooler. But the problem in FL would seem to contradict this theory
Are there two sensors? one for the Visual indictor and one that the computer reads?This is not a "defect". The miles-to-go computer is *not* directly linked to the tank. The computer *estimates* the remaining miles-to-empty; it takes an average fuel consumption over a given time period (1 min? 10 mins? 1/2 hr? dunno), and multiplies it by the number of gallons remaining in the tank (obviously time-delayed to some extent so that sudden changes in reported tank level as the tank float bounces around are ignored). If you just refueled, it takes a while for the miles-to-empty output to stabilize around any changes in mileage and/or gallons present.

[685ursus]

On my 05 LT the fuel guage occasionally will read near empty after a fill for quite some time as I ride on. This has happened twice and the tank was close to empty before the refill. I assumed the problem was related to the level sensor sticking in the tank. I added fuel injector cleaner to the tank and the problem did not reoccur until about 20,000km later (now over 30k on bike). I think that the use of the same brand of fuel can cause this. Fuel companies have their own unique additive packages. I do have a preferred fuel brand, however I now fill up with a competitive brand every 3rd or 4th tank. I am not a fan of using additives on a continual basis as over time the additives may cause problems similar to the problem it is supposed to prevent.
I have read articles written by chemists who support the theory of changing fuel brands to reduce the build up of a particular deposit formation. I work at a GM dealership and know first hand how one brand of fuel with their unique additive package can cause sticking or damage to fuel level sensors, in this case Shell Canada. If the fuel level sensor is sticking the BC and calculations will not be accurate the same as the fuel guage will not. I have not had my bike to the dealer as I feel the injector cleaner additive applied occasionally is the fix.

[bjr7742]

Thank you guys for this article, i just got a got my bike back from a water in the tank issue and got about 10 miles and the bike died. I found out later that the gauge was showing 1/4 of a tank and instead i ran out of gas. I am going to try the fuel injector cleaner and pray! 400 bones for a new sensor is alittle high. Thank you for your help.

canyon red k1200lt

:bmw:

[mneblett]

Thank you guys for this article, i just got a got my bike back from a water in the tank issue and got about 10 miles and the bike died. I found out later that the gauge was showing 1/4 of a tank and instead i ran out of gas. I am going to try the fuel injector cleaner and pray! 400 bones for a new sensor is alittle high. Thank you for your help.

canyon red k1200lt

:bmw:I doubt the issue is a chemically-curable matter -- there's plently of clearance along the float tube, so it's not very likely that deposits are "gumming up" the sensor.

If the gauge is stuck at 1/4 tank, you will likely find that the float tube is dented at that level. Relatively easy to check, and fix, if that's the issue -- no need to pop for a new sensor.

The unit is shown at page 16.8 of the Repair Manual. The upper fairing side panels and the radio stingray need to come off, then simply unbolt the float tube ("immersion tube") from the right top side of the tank and pull it straight out.

If there is a dent in the side of the tube, stick a rod/screwdriver/etc. up the inside and whack it back out, then reinstall the unit in the tank. That's it.

Of course, you should also try to figure out *why/how* the sensor got dented in the first place. The only three ways of which I'm aware are:

(1) Mishandling of the sensor during some maintenance activity (how did they remove the water from the tank, pull the sensor and siphon out the water? Did they actually confirm that there was really water in the tank?);

(2) Turning the gas filler nozzle to the rear during refueling (not likely this, as dents from this are typically much higher up the tube than the 1/4 level);

(3) Collapse of the plastic fuel tank inward due to build-up of vacuum in the tank (very likely, as the dents are typically at the 1/4 tank level). This is due to a blockage in the tank vent path, which in turn is typically due to a clogged charcoal canister and/or the hose leading from the tank to the canister. Search on "canisterectomy" for more info and a solution (canister removal and hose re-routing).

FWIW, if your original water-in-the-fuel symptoms were bike stumbling and dying, it probably wasn't a water contamination problem in the first place, but a clogged canister -- these symptoms and the 1/4 tank dent go hand-in-hand with a canister/tank vent issue.

HTH!

[km5bh]

typically due to a clogged charcoal canister and/or the hose leading from the tank to the canister. Search on "canisterectomy" for more info and a solution (canister removal and hose re-routing).

but a clogged canister -- these symptoms and the 1/4 tank dent go hand-in-hand with a canister/tank vent issue.

HTH!

I had the same problem last week. I unhooked the line to the cannister and it cured the problems. The stumbling feeling was the bike pulling a vacumn and not get enough fuel. The dent will required the tupperware coming off. 8-((


btw: will the canister dry out and cure itself.

Lewis

[mneblett]

btw: will the canister dry out and cure itself.Not necessarily. If you look through the archives, you will find cases where the charcoal formed a slurry which either hardended in place, or worse, was drawn into the hoses, further blocking the tank vent line. That's why the standard dealer practice is to replace the canister. Since we do not face the same EPA penalties as a dealer, we can remove it.

BTW, merely disconnecting the hose at the canister will provide a temporary fix (allowing air to get to the tank if the hose is not also plugged), but in the long term the hose should be re-routed in the manner described in the canisterectomy procedure. The hose from the tank goes from the top right front of the tank, down to the level of the right tip-over wing, back along the wing to the area under the seat, then back up to the elevation of the canister under the trunk. This creates a highly undesirable low "trough" in the hose, which can over time result in clogging and re-creating the tank vacuum problem. The permanent solution is to re-route the hose alongside the gas spill bib drain hose to the area behind the right footpeg.

[km5bh]

Thanks, I missed the mention of the slurry forming and hardening. I'll reroute the hose in a couple of weeks when I make some changes to the lights.

Lewis


Not necessarily. If you look through the archives, you will find cases where the charcoal formed a slurry which either hardended in place, or worse, was drawn into the hoses, further blocking the tank vent line. That's why the standard dealer practice is to replace the canister. Since we do not face the same EPA penalties as a dealer, we can remove it.

BTW, merely disconnecting the hose at the canister will provide a temporary fix (allowing air to get to the tank if the hose is not also plugged), but in the long term the hose should be re-routed in the manner described in the canisterectomy procedure. The hose from the tank goes from the top right front of the tank, down to the level of the right tip-over wing, back along the wing to the area under the seat, then back up to the elevation of the canister under the trunk. This creates a highly undesirable low "trough" in the hose, which can over time result in clogging and re-creating the tank vacuum problem. The permanent solution is to re-route the hose alongside the gas spill bib drain hose to the area behind the right footpeg.

[jers99lt]

I doubt the issue is a chemically-curable matter -- there's plently of clearance along the float tube, so it's not very likely that deposits are "gumming up" the sensor.

If the gauge is stuck at 1/4 tank, you will likely find that the float tube is dented at that level. Relatively easy to check, and fix, if that's the issue -- no need to pop for a new sensor.

The unit is shown at page 16.8 of the Repair Manual. The upper fairing side panels and the radio stingray need to come off, then simply unbolt the float tube ("immersion tube") from the right top side of the tank and pull it straight out.

If there is a dent in the side of the tube, stick a rod/screwdriver/etc. up the inside and whack it back out, then reinstall the unit in the tank. That's it.


My fuel gauge doesn't go below 3/8 full and the BC is also inaccurate at this point.
In the BMW repair manual (16.8) it notes a calibration procedure that relies on the MoDiTeC instructions. Is it necessary to have this capability to fix the float tube?
Thanks,
Jer

[jzeiler]

Jerry,


The Moditec is only necessary to re-calibrate the low fuel warning trip point. Sounds like you have a dent that won't let the float drop below 3/8. I would remove the float tube and inspect it for a dent or deformation (do this with little fuel in the tank). The float should move freely from top to bottom.

[jers99lt]

Jerry,


The Moditec is only necessary to re-calibrate the low fuel warning trip point. Sounds like you have a dent that won't let the float drop below 3/8. I would remove the float tube and inspect it for a dent or deformation (do this with little fuel in the tank). The float should move freely from top to bottom.

Should I assume that the originally calibrated low fuel point should still be set? I guess I'll find out once I get the float to slide freely on the tube.
Thanks for the very helpful reply,
Jer