Evinrude 50hp - Tach Stopped Working (is the Stator ok?)

[jimi]

My dashboard tach worked monetarily when I started up the engine this summer. The needle climbed to 1,000 rpm and then dropped. The engine seems to have lost a bit of its power but that could just be my perception.
It hasn?t moved yet. I check all the wiring and it seems fine. The signal from the motor is working but seems low, I measured about 2 or 3 volts at about 1,000 rpm. The sign comes from the yellow-gray lead off of the stator. Does that seem like the right voltage?

 

[interalian]

Have you tested your rectifier? Does the battery charge? Check also for loose or dirty connections.

 

[oldboat1]

^^agree.

 

[gm280]

When you read the voltage on the yellow/gray wire, did you have your meter set to AC? If not, try that and see what it reads. That voltage is comiig off the stator and therefore is an AC voltage. After the rectifier you can read DC voltage. And I think you should check that DC voltage as well because that is going to your battery to charge it. JMHO

 

[jimi]

I'll check the rectifier, make sure the battery is charging and check also for loose or dirty connections this weekend.

yes it was AC voltage, just seems very low. Does anyone have an idea what I should expect?

 

[interalian]

Do you have a DMM with diode test? Makes checking the rectifier a breeze.

To check voltage, measure AC volts between the yellow and the yellow/gray wires - these are the inputs to the rectifier. The stator windings are supposed to be isolated from ground.

With motor off and rectifier disconnected, measure ohms between the yellow wire and ground and from the yellow/grey wire and ground. These readings should be high/infinite. Then measure ohms between the yellow and the yellow/grey wire - this should be very low ohms, under 2 IIRC.

 

[gm280]

I'll check the rectifier, make sure the battery is charging and check also for loose or dirty connections this weekend.

yes it was AC voltage, just seems very low. Does anyone have an idea what I should expect?

jimi, The stator itself is not supposed to read anything to ground. If it does then the stator is defective. But you do that test with the stator wires all disconnected from the rectifier and separated from each other as well. And then you read resistance to see if there are any ground issues. Every stator wire should not read anything to ground. The wires can read between each other and that resistance is specified in the shop manual for each engine. But if any wire reads to ground, you have a bad stator. I am sure you understand and know how to read a rectifier. One direction the diodes will read a low resistance and the other way it should not read anything. And that goes for all the diodes in the rectifier.