Recent content by RRDave

  1. R

    1996 Mariner 9.9hp 4 stroke no spark

    I purchased a used 1996 Mariner 9.9hp 4S outboard and I can’t get it to start. Precious owner said he had it running a couple of weeks ago and that it’s always been reliable. I tested with starting fluid with no luck then pulled the plugs to confirm no spark on either. I also disconnected the...
  2. R

    6hp 4 stroke tohatsu (mercury) won’t reach WOT under load

    I hate to admit it, but I think the comments about engine too small and/or over propped are right. I took my other motor, which is identical, except long shaft and compared speeds. I also ordered a tach and did some measurements. Both idle about the same, around 1000 rpm and both reach a max rpm...
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    6hp 4 stroke tohatsu (mercury) won’t reach WOT under load

    I did start to think my expectations were too high, but have since seen multiple examples of the same boat (12’ aluminum Jon boat) doing 15mph+ with similar loads. Any difference in weight and/or distribution doesn’t justify the underperformance I’m experiencing (6mph max)
  4. R

    6hp 4 stroke tohatsu (mercury) won’t reach WOT under load

    Thanks for the replies. The carb was replaced because I thought it was the source of the problem, which I now know it’s not. I’ve used both a 7.8x7” and 7.8x8” prop with no noticeable different in speed (~5mph). The motor is on a 1236 aluminum jon boat (loaded with gear, battery, trolling motor...
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    6hp 4 stroke tohatsu (mercury) won’t reach WOT under load

    I have an early (late 90’s/early 2000’s) mercury 6hp (rebranded tohatsu). It has a new carb, new plug. It starts and runs excellent. In neutral, it can rev to the limiter, however, when in gear, underl load can not reach anywhere near WOT. It does however, run smoothly with the throttle wide...
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