User Tag List

Results 1 to 10 of 10
  1. #1
    Join Date
    Aug 2004
    Location
    Sault Ste Marie
    Posts
    27
    Thanks (Given)
    2
    Thanks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    V6 Mercury tachometer

    Having trouble with a V6 Mariner Mag3 factory tack which is unreliable, will work ok occasionally but the will bounce around and then return to zero. This can occur at any rpm and I have tried two different tacks, same results. Have rewired a new group d wire directly from the battery to the gauge. Same results. Then ran a totally new sender wire from the regulator to the gauge with the same results. Replaced the 12 volt accessory wire to the gauge and again the same results.
    How do I test the regulator output (grey wire coming out of the regular) should I be reading a low DC voltage at idle and increasing voltage with RPM or is there a different test I could perform. Have eliminated all other possible problems I can think of.

    Appreciate any advise as there is no tack troubleshooting info in my manual.

  2. #2
    Join Date
    Mar 2002
    Location
    Rockford, MI
    Posts
    1,875
    Thanks (Given)
    11
    Thanks (Received)
    15
    Likes (Given)
    57
    Likes (Received)
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Could be a rectifier. They make tach do strange things. If your Volts are running lower than normal also, it is probably the rectifier
    "The Flying Clamato"
    ...This ain't no Party, This ain't no Disco, this ain't no foolin around..."Talking Heads - Life During Wartime"
    The G-Train has left the station.

  3. Likes tux974 liked this post
  4. #3
    Join Date
    Aug 2004
    Location
    Sault Ste Marie
    Posts
    27
    Thanks (Given)
    2
    Thanks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Battery voltage remains good and starting has never been a problem with lots of cranking power, volt gauge indicates correct voltage with discharge and positive charge rate deflections once thru starting and trim operation.

  5. #4
    Join Date
    Jan 2003
    Location
    aalsmeer
    Posts
    1,463
    Thanks (Given)
    0
    Thanks (Received)
    163
    Likes (Given)
    12
    Likes (Received)
    259
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    You can connect a multimeter to the grey rectifier wire
    set it to herz
    If it is not stable the rectifier is probably suspect

  6. #5
    Join Date
    Feb 2009
    Location
    Edgewater,B.C. CANADA
    Posts
    8,260
    Thanks (Given)
    179
    Thanks (Received)
    321
    Likes (Given)
    3578
    Likes (Received)
    1236
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If you have regulators with grey wire the rectifier is built into the regulator. Try switching grey wire to other regulator if you have 2.

    Dave
    1980 Cougar 19 tunnel,90 2.4L Bridgeport EFI in middle of restoration.
    1988 BAJA Sunsport 186, 96 225 Pro Max
    79 12' Auminum, 95 Merc 9.9
    RIP Stu
    "So many idiots, so few bullets"

  7. Likes tux974 liked this post
  8. #6
    Join Date
    Feb 2013
    Location
    Northern Cal
    Posts
    190
    Thanks (Given)
    0
    Thanks (Received)
    18
    Likes (Given)
    8
    Likes (Received)
    37
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Normal Tach Rectifier output is shown on the right hand side of drawing below "Half wave" which drives the tachometer "upscale" only .
    The wave form on the left is what occurs with failed (or failing diodes ) and drives the tach needle up and down causing it to be unstable . Using a digital multimeter with hertz function you should read 6 positive pulses per engine revolution .

  9. #7
    Join Date
    Aug 2004
    Location
    Sault Ste Marie
    Posts
    27
    Thanks (Given)
    2
    Thanks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Yes this engine has 2 rectifier's. I will give that a try next time I am out to the lake. Thanx and hopefully that will solve the problem.

  10. Likes Dave Strong liked this post
  11. #8
    Join Date
    Aug 2004
    Location
    Sault Ste Marie
    Posts
    27
    Thanks (Given)
    2
    Thanks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    A big thanx to all whom have suggested easy troubleshooting tips. Will be a few days before I get back to the boat to try but will keep you's posted.

  12. #9
    Join Date
    Apr 2001
    Location
    Gothenburg, Sweden
    Posts
    7,057
    Thanks (Given)
    143
    Thanks (Received)
    60
    Likes (Given)
    76
    Likes (Received)
    334
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    As pointed out above, it is most likely the rectifier.

    If the tach works like it should when connected to the other half of the rectifier, you know for sure.

    Mercury rectifiers are junk. There is an aftermarket part for an Opel that gets the job done and lives much longer at a fraction of the price.__PRESENT
    Markus' Performance Boating Links:
    www.toastedmarshmallow.com/performance

  13. #10
    Join Date
    Apr 2011
    Location
    Long Beach
    Posts
    319
    Thanks (Given)
    0
    Thanks (Received)
    7
    Likes (Given)
    14
    Likes (Received)
    23
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    fought this same thing a couple years ago. bad rectifier.

Similar Threads

  1. WTB mercury tachometer
    By kvogt in forum Parts Wanted
    Replies: 4
    Last Post: 03-31-2016, 08:06 PM
  2. Mercury 10K tachometer???...
    By h2oskiier30 in forum Technical Discussion
    Replies: 6
    Last Post: 05-01-2009, 06:16 PM
  3. Tachometer On Mercury 25 H.p.
    By DonChicho in forum Technical Discussion
    Replies: 3
    Last Post: 12-25-2003, 09:50 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Frank Mole Transport