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I was running my 1982 Johnson 50hp outboard at 4000 rpm and coming into the launching ramp and when I pulled back on the shift/throttle lever the engine raced at very high revs and I had to stop the engine immediately with the ignition key. The engine is a J50BELCNR. I later found that the shift lockout lever was out of place and a piece had broken off and it also caused the idle arm on the control box to move up and down. I have opened the control box and jury rigged the plastic lever so it slides in the proper place again, but the engine when I try and start it, races uncontrollably and I have to switch off immediately. With the plastic lever removed, the engine still races in neutral. I now think that the original problem may be in the carbs or perhaps an air leak. Any ideas where I might look? I have checked the throttle and gear shift cables and they are fine. The carb linkages are fine and both internal plates open at the same time and are closed when the engine's in neutral. I "think" that the compression when I turn the flywheel (plugs installed) may be lower than normal, as I can turn it with one hand on the flywheel and I think it used to be harder than that. I am stumped and don't know where to look first. I would appreciate any advice.
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First... whatever is wrong with the control box, fix that properly. Don't do what we in the trade call "Mickey Mouse repairs."
Make sure that the control box (after repairs) is absolutely in neutral.
Make sure that the scribe mark on the metal cam aligns with the cam roller dead center and that this is when the throttle butterflies just start to open.
DO NOT have the metal cam touching the throttle roller on this step. Make sure that the linkage between the carburetor throttle butterflies is such that the butterflies start to open and shut at the same time. You do not want one butterfly shut and one ever so slightly open at idle.
Make sure that the top portion of the vertical throttle arm is connected to the timer base under the flywheel.
Now, with the timer base in the full retard position and the throttle butterflies not opened... the engine should idle. Does it? Did you find anything that was not as it should be? -
Engine Over-revving
Thanks for the speedy reply; yes, I am waiting for that new plastic part which is on order and not sure if that could lead to the over-revving problem, or whether it is a bi-product of it. It is connected to the idle lever, so I will replace that in the control/shift box first and then try all the things you suggested, so will get back to you with the results soon.Comment
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