Help with a 1971 Evinrude 125 HP

Turn the key and it slowly cranks like it's not getting enough power from the battery to start up but I have a full charge. I even tried hooking up a jumper to it and no difference. It started fine at the dock and then stranded us on the water.

I?m thinking solenoid but was looking for someone to confirm that idea or maybe provide a test I could run to further diagnose.

Thanks in advance for your help. Chris

Re: Help with a 1971 Evinrude 125 HP

Do you know how to do a voltage drop test, using a multimeter? That is the procedure of choice for checking the solenoid and also the cables and connections.

That said, it probably is not the solenoid. More likely a bad cable connection. Remove them and clean them and the battery posts shiny bright and reassemble tightly. Also examine them for signs of corrosion inside the insulating covering. Bulging or green would be such signs.

Voltage drop test across the solenoid: Put meter on a suitable range for reading 12 volts DC. Touch red meter lead to the big nut on the solenoid that leads to the battery. Touch black lead to the big nut on the solenoid that leads to the starter. It will read about 12V. Now have somebody turn the key to "start". The solenoid will click and try to crank the motor, and the meter should drop to virtually zero volts. If you have a few volts showing it is a bad solenoid.

The procedure is the same for the cables, connecting the meter to each end of the cable. In fact, it is the same for any connection, connecting the meter across the connection. Remember what you just learned: It is a "voltage drop test". Now people will be impressed with your electrical geniusness.

Re: Help with a 1971 Evinrude 125 HP

Thank you very much for your reply. I took your suggestions and confirmed the solenoid is fine. I cleaned all wires on both ends but it still won't start. As I was doing all that, it went from barely trying to turn over to not turning over at all. When you turn the key, it clicks back in the motor, the voltage drops on all connections including the starter, but no action from the starter. Now I'm wondering if that is bad. Real easy to replace but rather not spend $150 to find out that isn't the problem either.

How can I test if the starter is still good? Thanks

Re: Help with a 1971 Evinrude 125 HP

You should be able to test the starter by removing the black and red wires to it, then jumping it with a set of car jumper cables. If the starter turns over easily, it should be fine. If the starter is slow, don't immediately replace it. You can disassemble it and you may find all it needs new brushes, cleaning and some new grease.

Re: Help with a 1971 Evinrude 125 HP

Have you tried to rotate the flywheel to ensure it turns and is not bound up?