My 86 80hp mercury outboard lacks power. It has even compression on all 4 cylinders what could be my problem?

Question

My 86 80hp mercury outboard lacks power. It has even compression on all 4 cylinders what could be my problem?

Answer 1

OK, remember, your merc is a 2 cycle motor, that is a little different from a 4 cycle in that the compression while important, is not going to be as high as a 4 cycle-  If the engine will start, but not pull the boat, you have to consider the following.

1. is your fuel system allowing enough fuel to get to the cylinders?  You check this by clearing the fuel lines, clearing any fuel filters, and making certain there is sufficient fuel reaching the cylinders.  THIS IS THE MOST COMMON REASON FOR FAILURE TO PERFORM-often plugged jets in the carb(s) or a plugged fuel filter.  If everything else is good, remove and re-build the carb system.  This is not for novices, and should be entrusted to a certified mechanic, so don't do this unless you know what you are doing.

2.  Spark-this is a less common cause of what you are describing, as most of these have a magneto style ignition, and are usually pretty dependable, this problem also involves the wires and plugs, and all of that should be checked and confirm they are in good service.

3.  The operating cables.  I know this is weird, but cables go bad on the control system on a boat.  It is possible that you may not be getting full throttle operation when you think you might.

these are the most common problems, although, certainly there are potential problems-good luck in finding the problem, and be safe when boating, the merc 80 is an excellent unit, and should give years of trouble free use.