Re: Where do I get a wiring diagram for an 85 hp johnson?
On that engine (1977 85hp Johnson), the ignition is self contained, meaning that it is not dependent on battery voltage. In fact, battery voltage would damage it! The stator under the flywheel is a two fold component... a series of small coils within it is for the battery charging system, BUT there are two larger coils within it... one located at the front of the stator and one at the back of the stator. These two coils supply approximately 300 AC volts to the capacitor within the powerpack in order to engage the ignition. So you can see that the stator is the beginning of both the charging and ignition system.
Look closely under the flywheel to see if there is any traces of a sticky looking substance dripping down upon the timer base and/or powerhead area..... and if so, replace the stator. The dripping would indicate that the stator has overheated and therefore would encounter a AC voltage drop to the powerpack capacitor, resuslting in weak, erratic, or no ignition.
If the stator looks okay, remove the black/yellow wire from the powerpack (Kill circuit). Remove spark plugs. Rig a tester of some kind whereas you can set a 7/16" gap for the spark to jump (the 7/16" gap is important!). DO NOT use the spark plugs to test the spark.
NOTE: The engine must crank over at least 300 rpms in order for the stator to engage the ignition so be sure to have the spark plugs removed in order to obtain the highest rpm possible.
If you have spark with that wire disconnected but no spark with it connected, then either the engine wiring harness has a short in it or (since the RED electrical plug has been cut off) the wires are touching at their cut off point.
If no spark with that black/yellow wire disconnected (assuming that the stator is okay), the probem is usually a blown powerpack.
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