1 Fuel pump cutting out and a bonus mystery... Wed Oct 04, 2023 3:22 pm
KEVVYMETAL
active member
I'm puzzling this out, but posting in hopes one of the smarter K gurus knows this issue:
91 K100RS, with very little (mile)age-related problems because it got put away with 39k miles in 2004
The fuel pump is more or less intermittent: once running I havent had it cut out (yet), but starting is an issue. Pump runs briefly as normal when bike is powered and all is working BUT more often now, no pump and of course no start. 4-pin pump/sender connection has been cleaned, ignition lubricated, fuses and holder cleaned. While fidgeting with the pump connector, and getting no result, I bumped the blue 2-pin in the same spot and found that moving THAT connector seems to have a major but inconsistent role. While bike is running, touching ONLY that connector can make the pump cut out. Likewise, if pump isnt working changing the position of that connector will get the pump connected and running again. Connector has subsequently been cleaned thoroughly, but moving/pulling/otherwise abusing the connection has no consistent effect on pump power. It just seems to stand, right now, that futzing with THAT connector is the thing that consistently affects pump operation.
To confuse me further: this morning bike started and ran great, but now fuel level float isnt showing on gas gauge which now sits at empty on a nearly full tank. SO! I suspect a link, but I dont understand.
The black 4-pin is fuel pump power and fuel sender, right?
What does the blue 2-pin connect?
The only other possible mitigating factor (and I have NO idea if its related) is that while the bike runs gorgeously, the fake choke/throttle advance NEEDS to be in the start position for the bike to start (as opposed to my 1100 which almost never needs that choke lever moved), and while cold is does not like sudden throttle-off. A quick drop in RPM will stall it. This too goes away once up to temp.
Thank you if you made it this far.
91 K100RS, with very little (mile)age-related problems because it got put away with 39k miles in 2004
The fuel pump is more or less intermittent: once running I havent had it cut out (yet), but starting is an issue. Pump runs briefly as normal when bike is powered and all is working BUT more often now, no pump and of course no start. 4-pin pump/sender connection has been cleaned, ignition lubricated, fuses and holder cleaned. While fidgeting with the pump connector, and getting no result, I bumped the blue 2-pin in the same spot and found that moving THAT connector seems to have a major but inconsistent role. While bike is running, touching ONLY that connector can make the pump cut out. Likewise, if pump isnt working changing the position of that connector will get the pump connected and running again. Connector has subsequently been cleaned thoroughly, but moving/pulling/otherwise abusing the connection has no consistent effect on pump power. It just seems to stand, right now, that futzing with THAT connector is the thing that consistently affects pump operation.
To confuse me further: this morning bike started and ran great, but now fuel level float isnt showing on gas gauge which now sits at empty on a nearly full tank. SO! I suspect a link, but I dont understand.
The black 4-pin is fuel pump power and fuel sender, right?
What does the blue 2-pin connect?
The only other possible mitigating factor (and I have NO idea if its related) is that while the bike runs gorgeously, the fake choke/throttle advance NEEDS to be in the start position for the bike to start (as opposed to my 1100 which almost never needs that choke lever moved), and while cold is does not like sudden throttle-off. A quick drop in RPM will stall it. This too goes away once up to temp.
Thank you if you made it this far.