Down at the boat today. Started engine, no problems - when engine was warm the reading from the volt meter at the coil was 7.5 to 8.3 volts. I suspect this should have read around the 12 volts. There was no difference in the reading when I applied a load such as the trim tabs..
However, with the volt meter connected to the + coil and the - direct to the engine block I got a reading of 15 volts.
If I kept the connection of the volt meter to the + and - of the coil and increased the revs, I got a reading of 18+ volts, sometimes off the scale where the meter would not give a reading.
When the engine started to misfire, the volt meter was reading 9v at approx 1100 revs however if I operated trim tabs, then the revs would increase to 2000 revs and the reading would increase to 13v.
I run a wire direct from the battery + to coil + when the engine was misfiring, it did not make any difference to the misfire but run smoothly when I applied a load from the trim tabs.
Is this a coil problem or what is the next test.