i have a 2000 mercury 150 efi with an intermittent fuel pump problem. when i tried to start the boat yesterday, i noticed i did not hear the fuel pump turn on and not surprisingly, neither did the motor. when i tested the poles on the fuel pump on top of the VST, i got 12v on the positive and 12v on the negative. is this right? i expected the negative to be a ground. when i jumped the negative pole to ground, the pump turned on and the motor started. if i removed the jumped ground, the motor would cut off UNTIL the motor was fully hot at which time the negative pole was reading zero. SO, cold engine getting 12v at negative fuel pump pole and hot engine getting zero at same place. does this figure to anybody? for a little background, the motor has been dropping two or three cylinders for the first few minutes of running under load the past three outings. each time, the problem has fixed itself and not returned until boat sits overnight. bad fuel pump? bad ground?
thanks!
thanks!