Marine: Boating, Sailing, PWC, GPS and Navigation - jerk in motor

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rwalters2230
06-06-09, 08:13 PM
i have a 25hp johnson on a 14 ft flatbottom,just bought it from a friend who rarely used it and put it the shop and had it tuned up,rebuild carb and had a fwd/rev cable replaced.when i fisrt took the boat to the river i was going slow and the motor would jerk about every 15 to 20 seconds and when i gave it full throttle it jumped out of gear and would not go back into foward but would go into reverse so i adjusted the cable and it went back into gear but still had a jump or jerk in it so i adjusted the cable several more times but still while i was going foward the motor would jump or jerk about every 15seconds.
help

samuari
06-09-09, 09:17 PM
Welcome to thew board.

If the jumping seams like it's the gearcase drain the gearlube and look for metal. It might be your gears sliping. Otherwise take a timing light and while underway use it to see if you are loosing spark.
Tijoe
06-13-09, 07:40 PM
The jerking feeling may well have been a misfire in the engine.
Is the state of tune in order, sometimes a carbon treatment will resolve many issues. I use Sea Foam, at least thats what I believe it's called.
Bill