I have a 79 mercury 40hp . the motor acts like its weak what could it be?

Question

I already rebuilt the carb, changed the spark plugs and wires and it still boggs down with more then one person on it, it won't even get up to speed with me and my wife on it and i also tried to mix the oil differently with the gas and usually i can figure things like this out any suggestions

Answer 1

DO A COMPRESSION TEST

Answer 2

I agree with Eddie. Check the compression. The rings or cylinder walls could be worn.

Answer 3

Hi buddy - short and sweet CDI.......check out the ignition console by swapping over yours with a buddy's. Electronics are fickle things.

Answer 4

your problem may be worn out engine seals where the engine isnt holding enough compression. Take off the top end of the engine and buy a new gasket set.

Also what sometimes happens is the engine gunks up from the inside. Try buying some "seafoam" from your local auto parts store. It will clean out all the gunk inside the engine and help restore power.

Have fun