Johnson 20HP wont rev under load, have paid to have water pump, spark plugs and check carbi but will rev with the ears in and for about 30sec in water then nothing then drives at about 2knotts
Boating - Light - Outboard Motor Boat Bass Fishing Saltwater Base
Answers & Comments
Try changing the prop to a smaller pitch my 20' chaparal had no hole shot with a 14.25" X 21" changed to a 13" X 19" and then I could pull 3 skiers up no problem. Same prob with my 25hp in 14' starcraft tried different prop to get more speed and it overloaded motor
Many things you could check.
Engine to small for the boat.
Not enough fuel deliver when in full throttle.
Gas pump.
Engines compression test.