Tach drops to 0 after 2000 rpm

Discussion in 'Outboard Maintenance' started by Dillusion, Jun 29, 2013.

  1. Dillusion

    Dillusion devilray snob

    Brand new teleflex 7000 rpm tach
    Yamaha 50 2 stroke

    I have the teleflex tach hooked up properly to the yellow/green/black leads on the wiring harness in my console. At idle it works great, says I'm getting 800-900 rpm like it should, but when I begin to hit the throttle once I reach about 2000-2500rpm the tach will stop and then go back down to 0 even though the engine is obviously running much higher.

    I did some searching and I might need a resistor? Anyone see this issue?

    Previous searching yielded this:

    3. Some Evinrude/Johnson 48 (50), 88 (90), & 112 (115) "Spl"
    engines may require the addition of a 1/2 watt (or larger), 2000
    ohm resistor, connected between the Tachometer's "Send"
    and "Ground" terminals. If the pointer drops back to "0" as the
    engine accelerates (around 3500 RPM), the resistor is needed.
    Replacement 12 Volt Light Bulb (with wedge base socket):
    Teleflex Part Number - IA62995
  2. Dillusion

    Dillusion devilray snob

    I went to radio shack and got a 1/2w 2200ohm resistor and connected it to the send/gnd terminals like in the solutio above but that did not fix it.

    Any more ideas?

  3. Creek Runner

    Creek Runner Well-Known Member

    Hey Matty, sorry for the late response been down in your neck of the woods fishing a tourney.

    What pole setting do you have the tach on?
  4. Dillusion

    Dillusion devilray snob

    I had it all ass-backwards ;D I had it set to 3P instead of 3C/6P I guess when I was staring at it, my brain wasn't working correctly.

    Also, My leads coming from the yamaha harness werent on correctly. To me- red should be constant power, black gnd, yellow switched power, and green signal. But in reality the red is IGN, yellow is unused (probably switched power for a warning light for a yamaha gauge), black is GND, and green is signal.

    Now that I have the harness correct and the correct pole setting it's good to go.
  5. Creek Runner

    Creek Runner Well-Known Member

    Yeah it sounded like a pole setting.

    Glad you got it worked out boat looks good!