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Recent content by johanwahlberg

  1. johanwahlberg

    -79 Triple 70hp lost thrust revs fine

    I’m back with new Merc triple trouble. (Mariner 1979 3 cyl, 70hp) Last evening, after putting the boat in water after winter, we went for a test run and suddenly, at 25 knots, the boat slowed and the engine ran away in ”neutral”. We lost thrust completely, no gear forward or backward. Wires...
  2. johanwahlberg

    Possible carb flooding -79 Mercury 70hp 3cyl

    Is the fuel pump diaphragm supposed to be wet on the INSIDE? These photos are taken just after replacing the fuel pump gaskets and diaphragm, and then starting up for a couple of minutes. The rear, large chamber (to the left in the left photo) is dry, but the two smaller chambers are wet as...
  3. johanwahlberg

    Possible carb flooding -79 Mercury 70hp 3cyl

    Been into the carbs once more, increasing the floats height to 0.75 in. (the new floats recommended 0.65-0.69). The top carb stays dry, but the lower seems almost to flood more. Weird thing is that it does really not seem like the fuels is coming from any of the jets or ventilations from the...
  4. johanwahlberg

    Possible carb flooding -79 Mercury 70hp 3cyl

    Hi again. I'm revisiting this issue this season since I never got it solved. I have now "rebuilt" the carbs with new floats, seats, needles and gaskets. "Vice tested" them as fastjeff suggested with the bulb rock hard. No leakage - perfect. But after starting her up in a rain water barrel the...
  5. johanwahlberg

    Possible carb flooding -79 Mercury 70hp 3cyl

    Hi! All last season I noticed how it started smelling a lot of gas after a ride, a while after the engine was turned off. Also a lot of oil shimmer spreading on the water surface around the outboard. When tilting the engine up, fuel/oil drips down on the transom. Some weeks ago when I started...
  6. johanwahlberg

    Newbie prop question 13" vs 14"

    Hi, sorry to bother you with such a basic question which probably is googleable, but i cannot find the right keywords. I have a small hardtop with a 1979 Mariner/Mercury 70hp 3-cyl. The previous owner was a very big person and was using the boat for water skiing, so he changed to a lower pitch...
  7. johanwahlberg

    Found the wrong plugs installed (1979 70hp Mariner)

    Hi, I ran my engine about 50 hrs or less last season. It worked perfectly fine, until the last 4-6 weeks when it started to almost stall in low rpms. It has always been a bit rough at idle up to a threshold rpm level at which it smoothens out and start spinning like a cat... However, last...
  8. johanwahlberg

    70hp Mariner unstable at low rpm (Video)

    Hi, got our first boat this summer, an 80's 16 ft hard top, just for trying out boat life. The enginge, 70hp Mariner, 2-stroke, 3-cyl from 1979, has worked fine except for a few occasions (of seemingly increasing frequency) where it has been running unstable below a certain rpm threshold. It...
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