3-4 volts at the starter indicates it isn’t getting full battery power. Something in the circuit is causing this and if it isn’t loose or corroded connections, it’s highly probable it’s the starter switch itself. Since these starting systems don’t use a solenoid, the push button starter switch has to handle all the current going to the starter. It’s also mounted outside the front of the motor and exposed to water and salt which isn’t good for anything electrical.
The starting current also goes thru the neutral safety switch mounted on the starboard side of the motor and if either it or the starter switch are faulty, it wont crank over. The neutral safety switch also has to be adjusted so it will allow continuity only with the shift lever in neutral.
To test the system, a heavy wire can be used by connecting one end to the positive post of the battery and touching the battery side of the safety switch while in neutral. The motor should crank over. If it doesn’t, suspect the safety switch and then touch the other side of the switch or the terminal on the starter. If it doesn’t crank over, suspect the starter or ground connection on the motor. If it won’t crank over with the starter button pushed in but it will by bypassing the starter switch, it’s probably the starter switch at fault.
The starters are quite simple on these motors and can easily be taken apart for inspection. Dry and dirty bearings, a dirty or worn commutator, worn or hung brushes can all contribute to lazy cranking.
