Fuel strip failure - anyone seen this mode?

[deilenberger]

Went to Hatfield PA today to help set a Guinness world record (Hi Bill!) for the most BMW motorcycles riding in a group. Had a nice ride out, had a nice ride on the event, came back to the dealership (Montgomery Cycles) - had some water and another hot dog - and when it started sprinkling I headed for home.. and when I started the bike, the fuel gauge was now reading FULL (it had been reading about 3/4 full before) and the bike thought I had 220 miles left in the tank (after going 85 miles to get to the event from the last fillup..)

The miles to go did slowly reduce itself - but not to anything resembling reality, and the level on the gauge dropped also. It got down to 1/2 - and still thought I had 141 miles of fuel left (at 161 miles travelled @ OBC calculated 53 MPG).. and I put 2.82 gallons in the tank. It was showing a tad below half-full when I filled it.

Calculating with my calculator - 161 miles/2.82 gallons = 57 MPG. I've never done 57 MPG. I didn't burp it quite as many times filling it - but the level was above the bottom of the red funnel thingie.

Looking at what it thought I had left (141 miles/57 MPG = 2.47 gallons left in the tank - it thinks.) That would mean it thinks the tank holds 2.82 + 2.47 = ~5.3 gallons. I do have to admit - I've put > 5 gallons in once or twice.

If you use it's calculation of 53 MPG (141 miles/53 MPG = 2.66 gallons left in the tank - it thinks.) That would mean it thinks the tank holds 2.82 + 2.66 = ~ 5.5 gallons.

The miles on the tank (with 18 miles on it since I filled it up) are at 270 miles remaining... which sorta makes sense if the OBC thinks I'm getting 52 MPG. 270/53 = 5.09 remaining.

I'm all confused. Mostly 'cause of the oddity of the tank being at 3/4 then jumping UP to full. And no - I did leave the key in the bike, but unless someone filled it up while I was peeing.. I'm really puzzled.

Did put new tires on last night - but they aren't over-inflated.. and a good part of the 161 miles were highway at 70-80 MPH.

Since my warranty is up in a week (miles and time) - guess it's time to call the dealer and get this on record.

Confused back at the NJ Shore..

Just thought of something. When I filled it up - I did notice how cold the gas was - it was actually quite chilly (probably around 40F or so..) then when it appeared as a full tank - it had been sitting in the hot sun with a hot engine under it.. could the gasoline expand that much? Maybe my fuel strip is still OK.. I do recall that it usually takes 50 miles after filling before the fuel gauge starts moving... so expanding fuel, plus the 50 mile inaccuracy = full fuel guage? Might be.

[ShinySideUp]

I found online that the standard coefficient of expansion for gasoline is 0.069% per degree Fahrenheit.

I don't know how many degrees your gasoline warmed but you could probably make a SWAG given what sounds like a hefty temperature differential.

I wonder if the AIR in the tank expanded to put more pressure on the liquid portion, fooling the sensor. Did you try opening and closing the fuel filler door?

BTW, I often get 5.5 gal into my tank.

In re-reading your post, I think the main factor to rule out: you didn't accidentally pee in your gas tank!

[red baron]

The best mileage I ever achieved on my 08 R1200R was 50 miles/gallon driving in higher altitute at speeds between 45 to 55 miles per hour. As mentioned by the previous reply also I have been able to add 5.6 to 5.7 gallons when filling up just below the overdflow level. Gas without ethalon also greatly improves mileage.
Peter

[jed1]

Hi deilenberger,

Ive just recently noticed the same thing on my bike. My bike too expires its warranty at the end of May. Recently I was out for a ride and pulled up at a place with about 3/4 tank left. When I got back on the bike, the fuel gauge showed full again and it took about 10 km's of riding before it dropped back to the correct level.

Thats one of about 3 things that I need to tell my local dealer about before the warranty expires. I love my bike, but Ive never had these problems with a Japanese bike before.

[websterize]

Don, my first fuel gauge gave similar, squirrely readings before not working at all and was replaced under warranty. I'd drop by the service department this week.

[deilenberger]

Warranty expires tomorrow. They've examined it - and find the strip is defective. Going in on the 21st to get it fixed..

Whew. Just under the wire..

[vroomr]

I had that very same thing happen on a new F800GS. After probably a hundred miles after fill-up, the gauge was down a couple of bars, but then, mirabile dictu, it became full! Happily, it was a rental bike.

Repairs just under the warranty wire are so satisfying, aren't they?

[deilenberger]

Repairs just under the warranty wire are so satisfying, aren't they?

Doubly so when it's the only real warrany claim I've had (I had a master cylinder replaced for mushy brakes - but it wasn't the cause.. old one was probably just fine..) Oh - I also had one 8mm screw replaced under warranty - from one of the bag hinges (I tend to over-stuff the bags..) ALL those screws are now loctite'd in..

[AncientMariner]

My roadster is in the shop for a fuel guage indicator issue. Since it crapped out a few weeks ago, I've revertted to using the trip meter. On a recent Yankee Beemers ride to Gould's Sugar House for waffles, I topped off and reset the trip meter for the ride home. After 126 miles of half highway and half secondary roads, I refilled with only 1.89 gallons, 66.667 mpg!

[Paul]

Funny, i've got stuck on I-95 coming home from work a month ago, the OBC was telling me i still had 14 miles available.
This morning, on my way to work, the bike did the same thing but, the reserve light never came on and the gauge had three or four bars on it.
I pulled the clutch and was able to drift out of the exit and i had to push the bike only a few yards into the gas station.
Lucky.

I just got the bike back from Razee's for the 600 miles service last week ($217 if anyone cares for comparison) and, on the receipt, the diagnostic didn't read anything wrong.
I'll take it back soon.

[motoracer8]

In 1985 I bought a K100RS that had a thermister that measured the temp of the fuel to turn on the low fuel light, it never worked right, it was replaced 2/3 times still the same. In 91 I bought another KRS, and it had a propper float to measure fuel level, it worked perfect for the 8 years I rode that bike. I have a 83 Yamaha that has a float type fuel gauge, it still works fine. One would think BMW would fugure this stuff out after awhile, sometimes simple low tech is still ok.

Ken G.

[deilenberger]

Ken,

I think what happened is the engineer who designed the K bike one (I had an '85 - I know the problem..) finally retired or died, and some new kid engineer came up with this WONDERFUL IDEA, and the old guy wasn't around to tell him "there go your raises for the next 20 years.."..

History sort of does repeat itself. And corporate memories are only as long as the longest term employee.

[motoracer8]

Don, You could very well be right. I worked on German cars for 30 years, I started when they were fairly basic, Porsche 911's were just hot rod VW's, 2002's were fun to drive and you could work on them at home.
When I retired in 06 we had 4 different computers to track down verious probblems. BMW's I drive comes to mind, technology for technologys sake. Audi used a fuel sensing strip in some of their cars for awhile, then went back to a float for the same probblems BMW has with their motorcycles.

Ken G.

[qfman]

Don - apologies for the thread drift but I noticed something you wrote about mushy brakes. M non-ABS has had mushy brakes since day 1. By mushy I mean that I can pull the lever hard enought to juuuust trap my fingers but only when the lever is on its shortest/closest setting.
Is that what you mean by mushy? If so, and it wasn't the master cylinder, what was the cause?

Tom

[deilenberger]

Don - apologies for the thread drift but I noticed something you wrote about mushy brakes. M non-ABS has had mushy brakes since day 1. By mushy I mean that I can pull the lever hard enought to juuuust trap my fingers but only when the lever is on its shortest/closest setting.
Is that what you mean by mushy? If so, and it wasn't the master cylinder, what was the cause?

Tom

Tom - I'd suggest starting a new thread for it - for some background see the end of this thread: http://r1150r.org/board/viewtopic.php?f=20&t=19466 and I was looking for the thread where I posted the "solution" (as best as there is one..)

[Paul]

I'm keeping an eye on it.
It seems as if the OBC info is working and telling me that the miles left are getting less and less, although it's apparently off by fourteen miles or so.
The bars on the screen are just stuck, they don't go down.
I wonder why the computer doesn't pick up this discrepancy.

[deilenberger]

I'm keeping an eye on it.
It seems as if the OBC info is working and telling me that the miles left are getting less and less, although it's apparently off by fourteen miles or so.
The bars on the screen are just stuck, they don't go down.
I wonder why the computer doesn't pick up this discrepancy.

Paul - once the computer looses one of the inputs - it's hosed.. mine - the bars are apparently working again, but somehow the computer has it stuck in it's mind that I have an 7-9 gallon tank. When I fill it up - it thinks I can go > 280 miles... that's despite me resetting the OBC average MPG (and that is reading accurately according to my math.)

Since your bike is likely under warranty (600 mile service is a clue - you might add a "SIG" with that info in it - most of us here have, makes for a friendly atmosphere..) - let the dealer replace the fuel strip and mate it to the OBC.

[AncientMariner]

My new fuel strip has been installed (at 1700 miles) and everything is working fine.

Bruce

[Paul]

........Since your bike is likely under warranty (600 mile service is a clue - you might add a "SIG" with that info in it - most of us here have, makes for a friendly atmosphere..) - let the dealer replace the fuel strip and mate it to the OBC.

I bought it new about two months ago, a leftover from last year.

[vroomr]

After mentioning recently that I got one of the better fuel gauges, of course it bit me. My gauge ran down recently to two bars in what I consider a reasonable, linear fashion; my computer showed 75 miles remaining; I had driven 225 after a fill-up, letting the gas go slightly up the filler neck. My computer tells me I get 50 mpg, so if I started out with 4 3/4 gallons, I should've used 4 1/2, leaving a mere unwise quart. I've been lulled for three years into thinking the gauge was trustworthy, so I hardly consult the odo.

I took my bike out for a two-mile errand the other day. It showed two bars the whole time. When I started it today, it showed no bars, the warning light, and "---" as miles remaining. So, it looks like the two-bar reading was optimistic, and I guess the reading of bupkiss is on the pessimistic side. I wouldn't want to ride with one bar showing, but I thought I was safe with two bars, figuring I allowed a reasonable margin of error.

Of course, the computer should've indicated 25 miles remaining, not 75.

So, with no riding, a two bar reading turns into zero bars.

There's gas sloshing around in there, but who knows how much? It's seven miles to the gas station, Guess I'll bring the gas can in the car.