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I have crank, fuel, spark, and air flow. Bike won't even try to combust and at a loss. Mon Jul 31, 2023 4:12 pm
Mooselet
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Good afternoon! I purchased a 1985 BMW K75 back in April. Parked it in my driveway until I could get my endorsement straightened out, and we got hit with a massive sleet storm later that week. The storm knocked the bike over in the middle of the night and blew the cover off in such a way that it was covered with sloppy frozen precipitation the next morning. It has not started since. I should note that I am a novice in all things mechanical. I've maintained my own vehicles for years, but only through knowledge gleaned from YouTube and various forums, so there are definite gaps in my understanding and capability.
Crank
The first issue was extremely inconsistent results when attempting to start the bike. Following the start up procedures initially produced regular cranking of the starter but not starting, but after several attempts while fiddling with the choke and throttle, the starter would crank even after the starter button was released. I could stop it by turning the key to the off position. Additional attempts got even weirder. Once it stopped starting when the button was released, but then started cranking again when I released the clutch. I again was forced to turn the key to get the starter to stop. A quick search of the forum indicated a welded starter relay. I replaced the component with a Niche starter relay and the bike went back to cranking as it should following start up procedures. As far as I can tell, there are no additional issues with the starter, but the bike still won't start.
Fuel
After noticing no fuel pump noise, I pulled the fuel line to check the pressure. Stabbing the starter elicited only a dribble of fuel. Before I replaced the pump and filter, I replaced the obviously deteriorated fuel pump connector under the seat with a nice Deutsch connector. I still didn't have fuel pump noise, so I replaced the fuel pump and filter. This gave me a nice robust whir when I stabbed the starter and corresponding pressure in the line going into the injector rail. I also pulled the injector rail with all the injectors still attached and ensured I had good spray when the starter was pressed. This seems to indicate to me that I have good fuel flow and at least no interference from the EFI, but the bike still won't start.
Spark
I also pulled all the plugs and although they weren't pristine I had spark from all of them when I grounded them and stabbed the starter. I replaced them anyhow because plugs are cheap. I forgot to mark the cables and take a picture of the routing, but some quick research got everything back where it was before I touched it. I also sprayed ether directly into the cylinder while I had a plug out and didn't get a single combustion. As far as I can tell, I have good spark but the bike still won't start.
Air Flow
I pulled the air box apart to check the filter and the filter was also pristine. The bike wasn't purchased in a very dusty environment so this didn't surprise me. Spraying ether directly into the air conduit with the air box disassembled produced no combustion. I had a friend crank the bike with my hand over the exhaust and I got intermittent pressure from the cylinders moving, so it would seem to me that I have good air flow but the bike still won't start.
Miscellaneous
All of the fuses in the box on the left hand side of the bike seem to be intact. I have the bike on the center stand not the kick stand. The transmission is in neutral and the clutch is in. I put fresh gas in it and even if I didn't the ether should have at least ignited.
I'm not really sure where to go next. I'd appreciate any guidance on this. Thank you all so much for your time.
Crank
The first issue was extremely inconsistent results when attempting to start the bike. Following the start up procedures initially produced regular cranking of the starter but not starting, but after several attempts while fiddling with the choke and throttle, the starter would crank even after the starter button was released. I could stop it by turning the key to the off position. Additional attempts got even weirder. Once it stopped starting when the button was released, but then started cranking again when I released the clutch. I again was forced to turn the key to get the starter to stop. A quick search of the forum indicated a welded starter relay. I replaced the component with a Niche starter relay and the bike went back to cranking as it should following start up procedures. As far as I can tell, there are no additional issues with the starter, but the bike still won't start.
Fuel
After noticing no fuel pump noise, I pulled the fuel line to check the pressure. Stabbing the starter elicited only a dribble of fuel. Before I replaced the pump and filter, I replaced the obviously deteriorated fuel pump connector under the seat with a nice Deutsch connector. I still didn't have fuel pump noise, so I replaced the fuel pump and filter. This gave me a nice robust whir when I stabbed the starter and corresponding pressure in the line going into the injector rail. I also pulled the injector rail with all the injectors still attached and ensured I had good spray when the starter was pressed. This seems to indicate to me that I have good fuel flow and at least no interference from the EFI, but the bike still won't start.
Spark
I also pulled all the plugs and although they weren't pristine I had spark from all of them when I grounded them and stabbed the starter. I replaced them anyhow because plugs are cheap. I forgot to mark the cables and take a picture of the routing, but some quick research got everything back where it was before I touched it. I also sprayed ether directly into the cylinder while I had a plug out and didn't get a single combustion. As far as I can tell, I have good spark but the bike still won't start.
Air Flow
I pulled the air box apart to check the filter and the filter was also pristine. The bike wasn't purchased in a very dusty environment so this didn't surprise me. Spraying ether directly into the air conduit with the air box disassembled produced no combustion. I had a friend crank the bike with my hand over the exhaust and I got intermittent pressure from the cylinders moving, so it would seem to me that I have good air flow but the bike still won't start.
Miscellaneous
All of the fuses in the box on the left hand side of the bike seem to be intact. I have the bike on the center stand not the kick stand. The transmission is in neutral and the clutch is in. I put fresh gas in it and even if I didn't the ether should have at least ignited.
I'm not really sure where to go next. I'd appreciate any guidance on this. Thank you all so much for your time.