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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: stokester on March 24, 2022, 02:53:33 PM
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While this situation and solution may be familiar or simple to many of the long-time Motobrickers it may be of some benefit to those new to the joys of wrenching and riding our 2-valve K-bikes.
Bike - 1994 K75S, ABS Dakar Yellow - sat for years at a power sports dealership, I got it in 2018 with only 5668 miles on the clock. PO purchased it at the power sports dealer and took it to a BMW dealership for service. He rode it sparingly and sold it to me.
In 2021 I had it idling on my driveway ready for a trip to Morton’s BMW in Fredericksburg VA for an open house and noticed the smell of fuel with it visible on the case below the air box. This had happened to me before and I replaced the Oetiker clamp on the top of the fuel pressure regulator (FPR) which moved easily (I have a proper Oetiker pliers). This fixed the problem and I rode it for over 5K miles without any issues. Thinking the hoses to the FPR connector were hardened and now were not sealing I removed the air box and observed the hose to the fuel rail was easily rotated. After removing the hose it looked to be very stiff at the connection and long enough for me to cut and reconnect. After reconnecting with a new Oetiker clamp, reinstalling the the air box and tank the bike would not run. It would start but then die. I opened the fuel cap and listened while pressing the starter button, no sound from the fuel pump. I checked the fuse and found it open. Removed the tank, checked the 4-pin and looked at all the wiring to ensure nothing was worn or pinched. All looked good so I reconnected everything and replaced the fuse which opened after I pressed the starter button.
So, is the fuel pump shot? A possibility so I removed the pump (first year of the 43mm) and hooked it up to a 12v battery to find it working. Next I examined the fuel filter and found it to be pretty much clogged so a trip to NAPA for a suitable sub. I did find a bit of debris and water in the tank so a good cleaning and drying was in order. After reinstalling the pump with a new screen sock and fuel filter I reassembled everything, replaced the fuse and refueled. All is good and I let it run until the fan kicked in.
Having worked as a mechanic at a Chevy dealership under the flat-rate system I suspect this would have been solved at a dealership by replacing the pump and filter and calling it a day. Not to disparage a mechanic nor a dealership where time is money and replacing both components did solve the problem without much diagnostic time and it would help prevent a come-back if the pump has problems later. Your time as an owner is not billable so a quick check is a way to keep from spending extra money.
So this is not to trash a dealership but to encourage MOTOBRICK members and lurkers to search this site and take time diagnosing problems and fixing them yourself.