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Tohatsu trouble in low idle

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  • Tohatsu trouble in low idle

    Spent about a year fixing up this boat and motor and launched it for the first time yesterday. This was my first time launching a boat.
    14ft Achilles with a 40hp Tohatsu 2 stroke, the M40D.
    She started up pretty good with a little choke then ran fine in the harbor. Got bait at the bait barge and she started up fine again and I motored about a mile out to fish.
    With only one battery I wanted to start her up periodically since I was running the bait tank but had difficulty but she'd turn over after a few tries then I trolled to another spot a half hour away and parked and fished.
    At this point I could not get the engine to start without fast idle. I'd put her in a fairly high idle, slam dow the lever and throw it into full throttle and shed clunk and buck but I could move again. Then she'd run fine again.
    Got her back into the harbor and about 200ft from the dock she stalled out, I assume from the low idle speed. She stalled out 2 more times before docking and I started her back up the way I mentioned, with a buck and a kick.
    A friend said it was the ethanol in the gas.
    Anyone else experience this?
    I should mention I had the carb rebuilt by a Tohatsu dealer before this maiden voyage.

  • #2
    It's quite possible the battery was low? If there is not enough power from running the baitwell pump, and starting takes a lot from the battery. Outboards charge really slow. A half hour running isn't even enough to charge it up. The motor needs more than I think 10+ volts to run properly, running the baitwell pump would not help charge the battery.
    If ya can't fix it with a hammer,ya got yourself an electrical problem.


    • #3
      That motor only uses a bat to start it up, once started doesn't matter if bat is low. It's not an E related issue. That motor needs a full elecrical and fuel related troubleshooting as wild theoretical answers will go nowhere. Get a Service Manual, instruments and troubleshoot it yourself, sending that motor to a shop will result having a huge bill.

      Happy Boating

      Sea Rider 320, 380 Sibs, 450 Rib, 2 Strokes Tohatsu 5,18 & 30 HP Proud Smokers


      • #4
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        Thanks for the advice. I poked around here and found similar questions and answers.
        I started with my fuel filter and found a tear and there were bits of stuff in the reservoir and filter. Pulled the carbs and one of my slow jets was completely clogged.
        Blew it out, put it all back together and she started right up but still ran a little rough in low idle, seems to skip. But runs perfect at full throttle.
        My slow jets have rubber plugs so I bet the passages to them may be clogged.
        Guess I'll have to dip them.