First off, the amount of information out there on these motorcycles has allowed me to keep this one going for quite some time. Thanks for all of the info and help and effort to keep these guys alive!
I replaced the fuel pump recently on my 87 K100. The fuel pump was confirmed bad by a test outside of the tank. There was nothing that was concerning before the fuel pump went out, it just went out suddenly while merging on the highway. Replacement was tested outside the tank before install and proved to be working. I get it all reassembled, key turns everything on, starter cranks, but no whrrrr. Open the fuel tank and see that the pump isn't functioning. I have dug into many of the articles in this vein and haven't found anything similar. When disconnected, the two leads to the fuel pump on the 4 pin under tank connector shows 12VDC with the starter cranking and 0VDC with no start button pushed. I can jumper (only the fuel pump power wires) directly from the female side to the male side and the bike will start (basically skipping the two level sender connections). I opened the tank up last night and nothing on the inside or outside of that connection is fishy. I went through the fuel sender troubleshooting document out there, cleaned things up and reassembled. Still the problem persists!
The one clue I have is when I keep the connector connected and test straight to the wires inside the tank going to the fuel pump, they are -12VDC at no starter and 0 VDC at starter button depressed.
What does the root of the problem sound like to you? I'm deeply confused and feel so close to the solution, but it still is escaping me. Do I just need to cut the fuel sender wires?! I'd hate to do that by principle more than anything else.....
Thanks for any help offered.
