Mercury 90 HP 2 Stroke oddity

[Markus]

Best way to figure out whether a problem is fuel or spark related is to look at the spark plug.

Do like this:

Put in 3 new plugs and run the engine so that the problem occurs.

Then look at the plugs.

Wetter plug = no spark
Drier plug = no fuel

[Krazymaan]

get the motor started and point a temperature gun right where the spark plug meets the head at take temperature readings.