I doubt if the cost is much different - it was probably a lapse in corporate memory caused by someone retiring. As was mentioned, BMW tried the same sort of measurement device (whetstone-bridge) on the early K bikes. It worked equally as well, and after 3 years of making bikes where the fuel level was a guess, they went back to a float design.BoxerSteve wrote:It was probably the corporate bean-counters who asked the question, "what can we do to reduce expenses?". The fuel strip is probably quite a bit cheaper to produce than a more traditional (and reliable) float-type arrangement. In the long run it probably isn't cheaper since it has proven to be unreliable and many have been replaced under warranty. But bean-counters (and humans in general) don't usually think much about the long run.motoracer8 wrote:Sometimes I think motorcycle makers including BMW go looking for answers when no one asked the question.
The fuel strip has a lot going for it in theory.. no moving parts, able to fit odd shaped tanks (which is probably why the Roadster hasn't gotten a float) all solid state. Engineer's dream solution, an engineer who wasn't around in 1983-1986.
I'm heading to the NHTSA website to report it. Problem with reporting these sort of things on that website is - it's possible to report something in several different categories, and apparently government employees aren't good at correlating one failure with another identical one if they're reported in a different failure category. Once I sort out where I think it might best be reported, I'll post back here.
To the chap who has "30000km" (I'm assuming kilometers - so that's around 18,650 miles) - my first one lasted two and a half years and about 30,000 miles. I'm now at 62,500 miles and my 4th replacement one (meaning 5 have failed in total) failed over the weekend. It had been in the bike since about April of last year. 10 months and about 11,000 miles. Luckily since my first failed under warranty, and BMW has a 2-year parts/labor warranty on any replaced part, all of them have been free.. but I can imagine getting really really pissed off if this wasn't the case.
I don't think it's asking too much for BMW to have a working fuel gauge.
BTW - I've dissected a number of failed ones and did some elementary tests on them. The foil strip with resistive evaporated metal paths on both sides is not failing. The resistances measured at the top of the strip where it goes into a junction to the wires to the plug are what is expected. The wires from the plug into this junction aren't failing, they are actually fairly high quality teflon coated wires. The plug isn't failing. What seems to be failing is the junction between the wires and the strip inside the epoxy lump. Since I haven't succeeded in getting one of the lumps apart, I can't say for certain what the failure mode is, but given the symptoms, I'd suspect corrosion due to a faulty seal on the lump, or gasoline wicking down the actual wires from the plug area.
Does ethanol make it worse? Dunno - I have seen some reports of failed fuel strips on bikes ridden in countries where corn-squeezing isn't polluting the fuel supply, so I don't think that's the root cause of the failure. I asked one of the mechanics at my dealership while my last one was being replaced if BMW had any plans to address the failure - he said "Sure - keep replacing them.." It's not as if they don't know there is a problem. The NTHSA action will help bring it to the attention of someone high enough in the food chain at BMW to say "Fix it.."
