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Twin Engines Emergency Start Switch

Discussion in 'Electrical Stuff' started by Craig Lescombe, Oct 17, 2020.

  1. Craig Lescombe

    Craig Lescombe Member

    May 15, 2019
    Windsor, Ontario, Canada
    1990 350 Express Cruiser
    454 CID / 7.4 Liter Twins
    Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
  2. Siboatguy

    Siboatguy Active Member GOLD Sponsor

    Mar 28, 2016
    2004 Sea Ray 240 Sundancer
    1999 Sea Ray 290 Sundancer
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    I would have to say your switch for port engine is bad.... But don't hold me to it... Test it first..
  3. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Easiest first step would be to check your batteries and alternator. If you're getting wicked low voltage on the port side it would make sense that it won't run without getting 12V from starboard (when the emergency start switch is engaged).
    Woody, Riptide III and techmitch like this.
  4. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    First, turn off the battery charger if it's on. Now try it.

    If you are getting the same result, check all connections from the battery to the engine including at the emergency start solenoid. Take a emery board or sand paper and clean them very well. Clean all negative post on engines. Clean post and terminals on batteries.

    Have you load checked your batteries?
  5. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    Engine should keep running off of alternator output. No alternator output the engine dies. Almost certainly a bad alternator.
    techmitch likes this.
  6. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    Not really. I had the exact same problem on my boat this summer. Alternator was producing power, new batteries, replaced emergency solenoid, cleaned terminals, etc. Problem was still there.

    As soon as I turned off the battery charger the problem went away.

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