8.1 loss of Tach and momentary surge

Discussion in 'General Maintenance/Repair Questions' started by JMD, Aug 12, 2017.

  1. JMD

    JMD New Member

    Jul 31, 2017
    2006 Sea Ray 340
    Hello all, thanks for all of the information as I've been reading the forums for quite some time, but this is my first post.

    2006 Sea Ray 340 with 8.1's.

    After starting the starboard engine and idling for a couple few minutes, Smartcraft will emit a single beep, the starboard engine will surge from idle (650RPM) to about 850RPM, then return to idle. At the same time, the Starboard engine tach ceases working. Both the mechanical tach and the digital display 'die'. Mechanical goes to the 0 stop, while the digital display shows dashes. I need to verify today, but I think the depth indication also goes to dashes, but all other data remains good. The engine runs fine without the tach indications, and almost always the tach comes back alive later in the day. If I shut down the engine and restart, the tach works fine, until the tach decides to resume the above behavior.

    I've checked connections behind the gauge, but guessing with the 200RPM surge it is not a connection issue.

    Any ideas?

  2. paulswagelock

    paulswagelock Member

    Oct 25, 2010
    2018 SDX 270 OB on order
    Sold 2008 270 SLX 496 mag bravo 3
    Verado 300 pro
    Former 8.1 496 / bravo III
    On smart craft, the mechanical gauge is not mechanical it is smart craft driven, all the gauges are just needle representation of the smart craft signal.
    Can you hear the engine surge the 200 rpm or is the engine the same just the tach is jumping?
  3. JMD

    JMD New Member

    Jul 31, 2017
    2006 Sea Ray 340
    There's is an actual surge; only lasts about a second.

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