Tach problem Merc 25 hp 1997 25 EH 0G458399

[MIKE I]

Hi, added a tach recently while prepping a new hull. While engine was on the ground, hooked up tach and engine, cranked and got a tach signal. Finished rigging the boat and now have no tach. Verified power and ground to tach, Have proper pole selected and tach was tested when purchased. Disconnected tach wire from engine and put dvom to yellow wire at rectifier, should be 2.0v or greater getting just a few tenths. Also noticed on maiden voyage that the battery did not seem to be getting charged, though it is tough to say as we ran a baitwell pump all day. Can the rectifier take down the tach signal if it is bad? I do get an a/c signal from the yellow wire when cranking so it would seem the stator is OK. Any help is greatly appreciated!

 

[guyjg]

try this test http://www.myoutboardengine.com/rectifier.html

 

[mill686]

Not charging either? Rectifier?

 

[MIKE I]

Thanks for the help! New rectifier on the way and I will post results.

 

[MIKE I]

Installed the new rectifier this morning, the tach now works! At least while cranking. Will run it in the next few days. The screws securing the rectifier to the block were not clamping the base, so it would figure that there was at best an intermittant ground. One of the screws showed corrosion as well. Cleaned it up and applied a judicious serving of electrical grease to prevent a repeat, added a couple of washers so that the base is good and tight. Thanks for the help!