i have a 1985 k100rt and it would not start. i made some calls to bobs bmw in maryland and i unplugged electrical connector on gas tank ,sprayed it with electrical contact cleaner and coated it with dielectric gel. that fixed it. also check main grounding point on frame under gas tank.on a bike this old you need to make sure electrical connections are clean. the fuel pump is supposed to deliver fuel at 36 psi according to clymers repair manual. i hope this helped .