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4788 Cummins 6BTA 5.9 Starboard Preheater Inconsistent/Not Working

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    You guys are amazing. I so appreciate all of the tips. We have been following them along and checking everything you are suggesting. Each one begs a new question. All of the connections are tight. I changed the air temp sensor just to try and that wasn't it. I can't find the engine speed sensor some have mentioned. Does anyone have a picture that can point me to exactly what I am looking for?

    I think we have determined that it's definitely a power issue. If I turn the Perko's for both engines to BOTH, it works fine. So on its own battery, it's not getting enough power (I changed the battery to a new one too).

    The is one other oddball issue:

    When it is cold, that is when it doesn't work. If we go out for a cruise, even for a weekend, and go to start the engines to come home, it works. It's so weird.

    Thanks for the advice and if anyone has the picture of the engine speed sensor, I will really appreciate it.



      My 315HP 6BT's have the air intake heaters but the PO disconnected them in favour of block heaters. I have been keeping the engines plugged in and warm so I don't have too much smoking issues on cold start (except if the block heaters have been off for a while). I am considering testing the air intake heaters and if they are working, hooking them back up.

      Comments anyone...?

      M/Y Nitecap 1996 4788 Twin Cummins 315's
      12.5 KW Westerbeke Genny, Lewmar 185TT Bowthruster
      Leo & Joan Quigley
      Conception Bay South


        If it were me, I would hook them back up. There is no joy in a hard starting engine.
        Tony Bacon,
        Washougal, WA
        Caspian, MMSI 338355743
        1997 3788 Cummins 250hp


          I wired mine to a switch. If we are at anchor and engines have cooled down I energize them. Otherwise I just let the block heaters keep the engines warm
          2000 4788 w Cummins 370's, underhulls, swim step hull extension
          12' Rendova center console with 40HP Yamaha
          MV Kia Orana
          Currently Enjoying the PNW