Originally Posted by johnnytoobad59
While cruising at a steady 45, the bike surged and lost power. Roadside diagnosis showed all fuses good, no priming of fuel pump even after venting tank.
Starter turns motor, no start. Brought it home, found side stand switch broken, dangling under bike. Replaced. No start.
Easter- egged relays with known good. No start. Power to all relays and fuses, fuel pump kicks on when jumpered. No spark at plugs. All roads seem to lead to Motronic, but I find it hard to believe the computer just died.
Voxmagna already gave you several ideas.
Based on your description of problem, I am assuming that:
(1) when transmission is in Neutral, side-stand up, turning ignition ON does NOT make any fuel-pump priming sound for 1 or 2 sec.
(2) in same condition as above, when you press starter button, engine will crank but it does not start.
Symptoms above could be related to starter-safety interlock system (side-stand, neutral switch, clutch lever switch)
Check if you see the engine-temp light ON after ignition is turned ON. When this lamp stays OFF, it means the starter safety interlock is active. In addition to the classic scenario (side-stand down and transmission NOT in neutral), the starter-safety interlocks
will stay active (and prevent engine start) in these conditions:
- Side stand switch is unplugged
- One or two wire(s) of the side-stand switch is/are damaged, cut or shorted
Side-stand switch connector is located under seat, attached along the black tube sub-frame with 2 other switches (engine temp and neutral switches). To test this, you need to check female side of connector (leading to side-stand) by testing continuity of WHITE wire with BROWN wire when side-stand is up (PIN #1 and PIN #3).
On older K1200RS (before 2002 depending of country), the WHITE wire above could be BROWN+WHITE (combined color on same wire).
NOTE: If the engine temp light is ON but you still do not get fuel-pump priming after ignition ON, then the search for cause might be a bit more complicated (after checking fuel-pump with 12 volts power source direct obviously).