Retarded timing??

[maineleaf]

At times my 1984 20 hp Mercury outboard will not fully spin up. It acts as if the timing is retarded, then after a few minutes of running at wide open throttle, it will take off. Have rebuilt the fuel pump and even tried another gas tank, just to make sure that adequate fuel isn't the issue. any suggestions will be appreciated.

[boats.net]

Check the timing and spark when problem exists. Could also be a fuel related problem. Carburetors may need to be cleaned and adjusted.