Hello there, new user , first posting. I have a Mercury 4 cylinder/ 2 stroke 40HP 'C40ELPTO' (serial# 0G313349) that runs to maximum RPM fine when in neutral but only 3000 rpm when in drive (on a 22ft pontoon). The first outing this year the engine ran fine, second outing is when I noticed the problem. What I have done so far:
changed all four spark plugs (upper two were 'as new' , lower two had signs of carbon deposits)
replaced fuel line and primer bulb between tank (fixed 20 gallon) and engine
treated gas with 16 oz seafoam
used seperate fuel tank with fresh fuel
swapped fuel filter and fuel pump with spare parts (donor engine)
checked plug wire resistances (all very close to each other)
120 PSI cranking compression (throttle closed) all four cylinders
removed, checked and cleaned both carbs
checked choke solenoid for sticking (clamped supply line from carb bowl and disconnected wiring)
the only thing I did between first and second usage was add 2 stroke oil?? Again, runs to full engine speed ONLY when not in drive, in drive just reaches 3000 rpm?
Thanks!
Pete.
changed all four spark plugs (upper two were 'as new' , lower two had signs of carbon deposits)
replaced fuel line and primer bulb between tank (fixed 20 gallon) and engine
treated gas with 16 oz seafoam
used seperate fuel tank with fresh fuel
swapped fuel filter and fuel pump with spare parts (donor engine)
checked plug wire resistances (all very close to each other)
120 PSI cranking compression (throttle closed) all four cylinders
removed, checked and cleaned both carbs
checked choke solenoid for sticking (clamped supply line from carb bowl and disconnected wiring)
the only thing I did between first and second usage was add 2 stroke oil?? Again, runs to full engine speed ONLY when not in drive, in drive just reaches 3000 rpm?
Thanks!
Pete.