93 115 started then quit running

Went out yesterday and motor s

Went out yesterday and motor started at dock then died. Never started again. Where to start? Ran great 3 weeks ago. No spark to bottom cylinder. Any suggestions on where to begin my troubleshooting would be greatly appreciated.

"Ok, lets back up a little bit

"Ok, lets back up a little bit first.

You say no spark to number 4. Were you checking at idle speed?

Your model only fires on cylinders 1 and 2 at idle, 3 and 4 kick in above 1500 rpms or so -

so, if you were checking spark at idle you should expect weak/no spark at numbers 3 and 4 unless you bring the rpms up.

If she is gagging out when trying to idle, and you have spark to 1 and 2, then you should concentrate on the fuel system (which is most likely the culprit).

Anything from a clogged tank vent or pick-up, bad fitting letting in air, toasted gas line or primer bulb, bad fuel pump or clogged filter(s) or carb(s).

Could also be a simple as old gas or spark plugs that have outlived their usefulness.

What and when was the last regular maintenance done on the motor?

When did it last run properly?"

"Your motor is the 2+2 mod

"Your motor is the 2+2 model which runs as Graham said on the top two cyls only untill around 1500 to 1800 rpms and then bottom two cyls. This is done through the carbies not spark, they have very small low speed jets which allow some lubrication through but not enough fuel to fire the bottom two cyclinders."

Same year and Hp motor as I ha

Same year and Hp motor as I have. Interested to here the solution.