Re: 75hp fails under load
I'm not familiar with that particular.electronic ignition module. But, typically in those years, since it is a capacitor discharge system, if an electronic ignition goes bad, the engine will not start and run.
If the engine is starting and idling nicely, but dies when you give it power, first look for a fuel problem. First thing, check the fuel pump diaphragm--it's cheap so replace in any case. Then check the complete fuel system for restrictions and clogs.
One other thing to check would be the timing linkage. The plastic fittings that connect the linkage tower to the distributor get hard and can break with age. If they are broken and the distributor does not turn and advance the timing with carb opening, the engine will some times stall. Most times it will just bog down. Then again, if the distributor is wildly out of adjustment, when you advance the timing, it will go past the spark terminal and ground out, stopping the engine.
To check this, with the engine in neutral, turn the flywheel by hand until the 0 mark is at the pointer line (top dead center). At this position, the pulley on the distributor should have the curved line matching the flywheel curve and the center line pointing at or between the flywheel teeth. Then the rotor inside the distributor is in the proper position. If you need to re-adjust, loosen the two bolts holding the distributor and move the distributor to loosen the timing belt. Do not re-tighten the distributor belt too much The belt should deflect about 1/8 to 3/16 inch when a .010 feeler gauge is pushed against it like a finger and just starts to bend.
See if you can get a Clymers manual for this engine on line (3.5 to 140, 1966 to 1988)
