'72 Evinrude 100hp Safety switch function

I am trying to get this old boy running again. It used to turn over, but slowly (not nearly enough to start). After verifying I was getting 12 volts at both the solenoid input and from the key switch, I decided to replace the solenoid. Now, I get nothing (but I will recheck in the next few days)- ie- no noise, no action etc. Anyway, was thinking maybe something is wrong with the ground from the solenoid. According to the Seloc wiring diagram, this wire goes from the solenoid to a "safety switch". There is no other wire going to the switch (according to the diagram). What does the safety switch do, and can I ground directly to the block instead? Thanks in advance!

Re: '72 Evinrude 100hp Safety switch function

What solenoid did you use?

Re: '72 Evinrude 100hp Safety switch function

What kind of shape is your battery in and are all the battery cable connections good, clean and tight ??

Re: '72 Evinrude 100hp Safety switch function

#1, you must use the correct solenoid. A car solenoid will not work as intended and will instantly destroy the safety switch. But it can be made to work if you know how. However you will lose the safety switch function.

OK, with that out of the way, the safety switch prevents starting the motor at high throttle settings.

There is also a start-in-neutral-only function built into the 1972 shift switch. Both the neutral switch and safety switch must be functional in order for the motor to crank.

The solenoid probably was not the cause of slow cranking anyway. Instead of just throwing parts at it, a better course of acton would have been to do voltage drop tests of the starting circuit to find the real problem. A voltage drop test across the solenoid would have told you if it was bad or not. Same goes for the cables, etc.