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| 1976 johnson 70 hp bogging down helpf... |
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vic avarello
New member
Username: cobia
Post Number: 1
Registered: 07-2009
| | Posted on Wednesday, July 01, 2009 - 05:29 am: | 
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I'm posting this in hope that it will help the novice do it your selfer (as I am) diagnose the following symptom. Motor starts ok. If backing up will probably stall numerous times. Seems to Idle fine and will restart ok. Will putts along at low speed ok. When you punch it, it will die. Problem may come and go seemingly at will. The odds are that one of your 3 cylinders (but not all 3)has a problem. Either spark or fuel. But the other 2 cylinders are probably functioning fine. So the first thing to do is find out which cylinder is the culprit. Do this by disconnecting the plug wire on #1. If the motor won't hardly start then #1 is ok. Replace plug wire and proceed to #2 etc. When you find that by removing a plug wire that the symptom is exactly the same as described above then you've identified the problem child. Now find if it's spark or fuel. With plug removed (but attached to plug wire) use a piece of wood or wooden handle screwdriver to position end of plug to ground and see if spark exists. If not problem is in the ignition system. IN ALL LIKELEHOOD IT WILL BE A BAD IGNITION COIL. Of course it could be in the distributor , power pack etc. as well. If you have spark then it will be a carb problem. I am posting this hint because most times people don't keep it simple enough for us novices to understand how to eliminate the things that are working fine. Don't rebuild All the carbs if only one is screwing up. Don't pull the flywheel off and start with the distributor etc. if you can simply change out an ignition coil at 1/10th the time and expense. By the way I fought this problem for weeks before I found that my Ignition coil on #2 had a cracked casing and was intermittently arcking/leaking spark to ground instead of to the plug. I hope this helps. and doesn't sound to elementary. |
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