Key switch and Solenoid getting weird voltages 72 100hp Johnson

[GLE3]

Model: 100esl72r

Here is what my testing has uncovered:

Battery: Reads 12.2V

Key Switch: Battery terminal reads 12.2V in off position, 10.5 when turned to on. Solenoid terminal reads 0V when in on position

Solenoid: Outer post to battery reads 12.1V. When the key is turned to on, both inner posts read 0V. When cranking I am only getting 8.5 volts to the starter.


I've already replaced the key switch.

Engine will crank normally, but I've already put one power pack (@ $300) in this guy and want to avoid doing that again. My best guess being a novice outboard mechanic would be solenoid or wires to solenoid. Any further testing suggestions or bits of knowledge would be appreciated. Thanks!

 

[rockyrude]

Re: Key switch and Solenoid getting weird voltages 72 100hp Johnson

First, I would have the battery load tested. I've seen new ones load test bad. Next, check battery cables, they tend to corrode from the inside out. Solenoid should read 0v when in the on position, should only see volts in the start position.

 

[GLE3]

Re: Key switch and Solenoid getting weird voltages 72 100hp Johnson

First, I would have the battery load tested. I've seen new ones load test bad. Next, check battery cables, they tend to corrode from the inside out. Solenoid should read 0v when in the on position, should only see volts in the start position.

Thanks for the reply!

I ran over to autozone and load tested and they said the battery was good.



1. Test the ground circuit. Place your voltmeter + lead on a good ground on the powerhead, and the - lead on the battery negative post (not the cable, but the battery post). Turn the key to start position. The meter should remain at zero or close to it. If you get a significant voltage, you have a ground problem.

Got 0.74 volts for this test, is that significant?

2. Conntect voltmeter + lead to battery positive post, and - lead to the battery side of the starter solenoid. Turn key to start position and voltage should remain at zero or close to it. A significant voltage says a fault in the positive cable.

Got 0.74 volts for this test too, is that significant?

 

[boobie]

Re: Key switch and Solenoid getting weird voltages 72 100hp Johnson

The spec is usually 0.5 VDC. Yours is not that far off. When you get 3.0-5.0 volts or higher you got a prob.

 

[GLE3]

Re: Key switch and Solenoid getting weird voltages 72 100hp Johnson

Ok, I purchased another battery just to make sure that wasn't the issue. Ran some more tests. These numbers are without the power pack connected as I figured it wouldn't be good as it drops under 9.5 volts. I did run a couple tests with it connected and Voltage was .7 volts less than the numbers listed below(start position tests). Here is the voltages in the start position (thanks rockyrude):

Battery: 12.1 V (without load)

Solenoid: 8.7 V on one of the inner posts

Starter: 9.2 V

Just to see the difference I disconnected the starter and did the same test.

Solenoid: 11.2 V

Lead to starter: 11.7 V



Isn't the Starter's inner post supposed to be 12V regardless of cranking the engine?