Yanmar 2GM tackomerter help!!! - SailNet Community

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Old 10-11-2012
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Yanmar 2GM tackomerter help!!!

I need help. My tack stopped working? I checked it with a meter and it check 12.23 I donít know were it gets the information from. Is it the alternator? I canít find a diagram for the Tac. Any help will be great.
Itís a C&C 30MK1 with a 2GM 13 HP 3400 rpm diesel.
Thanks for your help.
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Old 10-11-2012
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Re: Yanmar 2GM tackomerter help!!!

I think the pickup is on the flywheel, not the alternator. The pickup could be dirty or worn out.
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Old 10-11-2012
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Re: Yanmar 2GM tackomerter help!!!

After looking at schematic on the last page of the manual at http://j30.us/files/yanmar-manual.pdf
it appears that the tach pickup is near the flywheel, as jsaronson has pointed out above. The wires are blue/red and white/red between the tach, and the pickup.

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Old 10-11-2012
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Re: Yanmar 2GM tackomerter help!!!

As mentioned the tach is taking a reading off the flywheel at the back of the engine. I would look at the connections there, making sure they are clean, and at the back of the tach, making sure they are clean and tight. The actual pickup rarely fail as it has no moving parts and are taking a magnetic reading as the teeth on the flywheel passes by. The only time I've heard of one failing is when it vibrated itself out too far to sense the teeth going by.

When you find the sensor make sure you are getting power at one side of it. You might look here and see if this helps even though it might not be exactly what you have, the concept will be similar. They also have a decent schematic. Good luck.

Troubleshooting Teleflex Tachometer Gauges

Scroll down to midpage where it is titled------

Tachometer (Magnetic Pickup) (Code B)
(For Diesel or Gas Engines with a Sender Mounting Point in Bell Housing or Adjacent to a Rotating Gear

This tachometer is for a diesel or gasoline engine having a sender mounting point (3/4-16 thread) in the bell housing (or adjacent to some other rotating gear), and 12-16 VDC (24 Volt systems can be accommodated with a Voltage Reducer).
Check all wire connections to see that they're tight and not corroded. NOTE: Some older style tachometers operate with only Ground and Sender connections. Teleflex tachs must have 12 VDC (from the ignition switch, "ON" when engine is running) to the "IGN" stud.
When tachometer is first turned on, pointer must go to zero 50 RPM. If not, check connections (if OK, tachometer is probably faulty).
Voltages with engine running should be: IGN to GND terminal: 12-16 VDC. SEND to GND terminal: 0.3 VAC minimum at idle; (voltage will increase with engine speed).
Set rotary switch on tachometer back to the range that includes the number of gear teeth that pass by the Magnetic Pickup in one crank shaft revolution. This information can be obtained from the Engine Distributor or Dealer. Arrow on slot must point to setting; if it is between settings, the tach will go full scale when engine is started.
Final calibration requires a Remote Master Tachometer. Connect Master Tach and start engine. At about 1,500-2,000 RPM, use a jeweller's screwdriver to carefully adjust the potentiometer in the "CAL" hole (about 10 o'clock on the rear of the tach), bringing the tachometer into agreement with the Master Tach. Only a minimal turning is required. Overtorquing of adjustment will damage gauge mechanism. Turning clockwise increases tach reading, counter clock wise reduces reading. If the tachometer cannot be brought into calibration, the black Range Selector Switch is probably on the wrong setting.
The end of the sender must be within 1/32" -1/16" of the gear teeth, but not touching the teeth. To adjust, stop engine, loosen the lock nut, and gently turn the sender clockwise until it touches the flywheel. Back off (counterclockwise) one turn, and secure with the locknut.
Rust buildup between the teeth can cause signal loss from the sender.
Dual stations: the sender will drive two tachometers. Simply connect "IGN" to "IGN", "GND" to "GND", etc. NOTE: mixing brands/ types (such as 2-wire/3-wire, see para graph 2 above) may cause problems.
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Old 10-11-2012
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Question Re: Yanmar 2GM tackomerter help!!!

did follow that to a pick up on the flywheel. I pulled the
connectors one is blue with a red stripe and one Orange . They looked
like a good connection? Maybe the tack its self? The light works on
the Tack. There is power to the tack. How would one check with a multi
meter the sensor end at the flywhell?

If I disconect the loud buzzer and I trace the 2 wires to the flywheel
should one wire should be with 12v yes? like on the 12 volt setting I
need to look for 11.53 thru 12.35
This wiring dig I have dont even show a Teck. "I does say Typical".
Look at my Engine head why is all the paint coming off it and not the block or the Transmission?


Last edited by ltgoshen; 10-12-2012 at 08:13 AM.
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