Re: speedometer inop
Speedo is usually a mechanical gauge, like a pressure gauge. it only works at speed, in the water.
The tach is electric. Check the back of the tach for +12VDC on a purple wire, Ground on the black wire. The grey wire will supply the tacj signal. Ohm it out to its termination at the voltage regulator on the motor. Most 90's motors of 150HP, have the VR behind the flywheel, on top of the block. When you disconnect the grey wire to the ohmmeter, it should be continunity to the gauge, but not to ground.
