Honda BF50 number 1 cylinder not firing

[Gilmore]

I have a BF50 4 stroke outboard (2006 model) that up until now has been a reliable motor. I was cruising at about half pace one day when the number 1 cylinder simply stopped firing, instantly. There was no "chugging" or anything and the engine continued to run. I have swapped the plugs around but the fault does not follow the plug. There also appears to be spark on that cylinder (I've been zapped by the lead because I didn't dry my hands enough).

The engine continues to start and idle easily on 2 cylinders. Anyone got any ideas on what could be the cause?

 

[Tig]

Re: Honda BF50 number 1 cylinder not firing

To fire a cylinder, you need spark, air and fuel. To diagnose your problem I'd try the following checks.
Run the engine wide open for a short period and kill the ignition. Remove all plugs and compare. Check for unburned fuel. Is plug one wet? (yes indicates ignition break down)
I'd also put a timing light on the plug wire to ensure that the ignition isn't breaking down off idle. This method is less painful that the one you previously used. (still firing after the cylinder quits indicates fuel problems.)
Going back to the info you provided, if it starts well and idles fine then it's probably getting spark, air and fuel at very low RPM. My guess is that cylinder one is starved for fuel when under load. Look in the carb. Blocked high speed circuit or stuck float will do this. Remove the carb it and have it (ultrasonically) cleaned. Might as well clean them all.
I hope this helps.