Most of us have heard stories of being left along side of the road when our BMW just stopped running without any prior indication of problems. Most shade tree BMW mechanics will immediately tell you there has been a Hall Sensor failure. In fact this may be true or it may not be true. I will relate three experiences I have had with sudden engine stoppage without prior notice.
First what is the Haul Effects Sensor? In simple terms, on the oil heads (the only ones I know about) there are two Haul effects sensors mounded on a steel place the fits on the front of the oilhead engine behind the drive pulley for the alternator. These sensors sense Top Dead Center (TDC) and 180 degrees on the crankshaft. On sensing these positions a signal is sent via wiring to the Motronic unit which in turn tells the coils to fire the appropriate spark plug and to squirt an appropriate amount of fuel through the fuel injectors. Of course the Motronic unit is monitoring a whole bunch of other crap such as battery voltage, oxygen sensor, etc.
1. Two years ago, Angie's R850R decided it would not crank after stopping for fuel. I had to haul the bike home from Moulton. Every thing pointed to a Haul Sensor failure. I decided to repair the old Haul Sensor by replacing the sensor on the plate (actually a friend did it for me.) After doing this the bike ran fine for approx. 2000 miles then it suddenly quit again. This sudden engine stoppage continued for about 3 months and cost us our bike trip to Alaska. The problem was literally driving me nuts and everyone kept telling me to change the Haul sensor. The problem was that it would run fine on some occasions and just decide to go dead whereever it seemed most inconvenient like Phenix City. I finally discovered she had a couple of grounding problems. The bike had lost its ground from the fuel sensing unit and I replaced this at a cost of $250+ then the problem occurred again. I finally noticed a short in the wire from the tachometer where the wire crossed a frame member. Repaired that and have had no prolbem in last two years. This bike had about 45K miles on it at the time.
2. Last year after swimming my R1100GS during a Waterloo run, the bike just shutdown about a 1/4 mile from the swim site. Had to haul the bike home. All indications were Haul Sensor failure, but first I wanted to inspect all the wiring for shorts since the bike has had a long history of wiring problems. Not finding any wiring problems, I ordered a Haul Sensor at about $250. When I removed the old Haul sensor, I noticed all of the lead wires from the two sensor to the pigtail that connects to the Motronic unit were brittle, cracked, and in a generally poor condition. I have attached photos of these wires (R1100GS-1&2). After the replacing the Haul sensor the bike cranked fine. This bike had about 92000 miles at the time of failure.
3. Sunday on the way home from the Chicken Rally, Paul Thorne's R1100R suddenly stopped running after he had just ridden through a rain shower. Terry Ware stopped to check on Paul and diagnosted the problem as probable Haul Sensor failure. Terry called me and asked if I could possibly help Paul since he did not have room in his trailer to carry Paul's bike. I told Terry, I thought I had an old Haul sensor and that I might get Paul back on the road. Short story - after hauling Paul's bike to my house, I could not find a Haul Sensor other than the old one I removed from my R1100GS and I knew the wiring on it was crap. Paul and Gail left the bike with me and I removed the Haul Sensor. The wiring on it may have been worse than the wiring on my R1100GS sensor. (See attached photos R1100R -1,2&3) I asked my friend, Mike Weyler, to come over Monday and see if we could replace the wiring on Paul's Haul Sensor. In fact we did and after reinstalling the Haul Sensor, the bike cranked fine and ran fine on a short 15 mile trek. Today I replaced the wiring on my old 1100GS sensor so I will have a spare next time. Paul's bike had approx. 96,000 miles at the time of failure.
What have I learned from this? Rarely is it that the actual Haul Effects Sensors fail but rather is a failure of the wiring which is attached to the front of the engine and absorbs all the heat over all the miles. Both of the R1100's had approximately the same mileage and the wires on both sensing units were in a similar poor state. If I owned a R1100 or R850 with over 75,000 miles I would immediately replace the Haul Sensor as a preventive measure. It doesn't take long in a hotel and with a recovery charge to pay for the $250 Haul sensor and labor if you have to have someone else replace it for you.
I don't have any experience on R1150 Haul sensors except that I know the part number is different from a R1100 Haul sensor. I do know I have 130,000+ miles on my R1150GS with no problems to date with the Haul Sensor, but I am seriously considering changing the unit out before a trip out west this fall. Then I can carry the old one with me along with all the other just-in-case parts I carry.
Why did I take the time to write all this crap up? Just to warn you that an ounce or $250 worth of prevention may save you a pound of problems down the road and ruin a good trip. Just envision the Haul Sensor dying on your high mileage bike late on Sat afternoon and ain't no dealer gonna to be open until Tues morning and then they have to order the part (cuz there ain't three dealers in the US that carry this part in stock.) If you are lucky and you didn't deal with Bogarts your part may arrive by Friday and the dealer may grant you special favor and install it so you can be back on the road on Sat. That's recovery fee, one week in the hotel plus meals that you didn't budget for.
Outlaw's tech talk for May.