I have a 1978 Mercury 20HP outboard on a 14ft. boat and am having major issues with propulsion. The gears will engage and the propeller will spin when you put it in gear. However if you give the motor some throttle it will NOT push the boat forward. It is almost like you are in neutral. At low throttle, the engine will push the boat along at a very minimal idle speed. Anything higher than low throttle and the motor will not propel the boat. It just revs up real high and with no thrust.
I suspect the problem is the propeller or some missing parts on the drive shaft. I bought the motor used and had to get a propeller for it. I purchased a NEW propeller from Michigan Prop. With the order, I got (1) propeller (1) spacer and (1) prop nut kit.
When the new prop didn't do the trick, I took to some internet research. From what I can find, there should be a slew of parts on the shaft behind the propeller. Please take a look at this schematic:
The parts I currently have on my shaft are #72, #71, and #70. Other than that, I don't see parts #59 through #69 on my shaft. Could they be hidden inside the housing? I have not pulled apart the lower unit, I have only pulled off the prop. When I do that, I see a shaft...that is all. Having no idea what should be on the shaft, I am at a loss.
OK guys...I hope someone can help me with this issue. I want to take my son fishing, but obviously I need a working motor to make that happen.