[maple_leaf_eh]

My neighbour, who had been talking me through some steps, suggested I pull the carb and look for mouse nests etc in the intake. Stranger things have happened he suggested, leading into yet another rendition of his story about 1 of the 3 carbs on an outboard engine being plugged with mouse fluff, pink boat house insulation and old kapok life vest filler. As he says: spark √ ; black plug electrodes; strong spark x4 √ ; fuel √ (gassy fumes from the cylnders when turned with the plugs out); backfires √ ; enough air, dunno. Maybe there isn't enough air getting into the cylinders because of something in the intake?

There were mouse turds and leaves in the heater box where the big hose fits. The carb intake isn't very far away ...