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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3341
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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My tach on a 2000 50hp jumping around engine seems fine indication

Customer Question

My tach on a 2000 50hp jumping around engine seems fine indication not emulating engine performance
Submitted: 8 months ago.
Category: Boat
Expert:  Charles replied 8 months ago.
Hello, my name is***** will assist you.How was the battery charge at the end of the day?Do you have a multimeter to do some testing?
Customer: replied 8 months ago.
Battery charge was in limits,
Expert:  Charles replied 8 months ago.
Ok, there are two possible causes for this problem, you will need a multimeter to locate the correct part. One is the voltage regulator and the other is the tach itself. Can you get a multimeter?
Customer: replied 8 months ago.
I have one, won't be out to the boat again until Saturday, tell what to check I can do it then
Expert:  Charles replied 8 months ago.
on the regulator itself, set the meter to DCV a scale close to 20, then with the engine running, measure the voltage on the red post of the engine while at idle and at 1500 RPM, you should see it go up from that the battery is just sitting static. Then on the back f the tach, black meter lead to the black wire on the tach, red meter lead to the gray wire Meter set to ACV, a low scale as this usually runs around just a few volts. See if the meter will move at all with the motor at idle, If you get a steady peak reading on it, the tach is bad, if the reading is constantly changing to a higher and higher voltage, it is the regulator. Let me know what you find out.
Customer: replied 7 months ago.
Will do, voltage regulator under cowling?
Expert:  Charles replied 7 months ago.
Yes under the engine cowling, should be on the right side of the engine.

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