40hp Mariner problems.

Hello all! Just wanted to say thanks in advance for any help on this problem.<br /><br />I've just picked up a 1984 40hp Mariner that looks in great shape, and ran great when we tested it in a tank. I took it out on the water today, (Mounted to a 16' Boston Whaler style boat), and it seems to bog under load. It needs the choke on all the time to get moving at all, or it conks out. Top speed seems to be about a fast jogging pace. It winds out in netural, and sounds healthy, but no luck in gear. Before it passed away I had an older 25hp that moved it along the lake much better. <br />It's a pull start motor, and the boat has a built in fuel tank with it's own fuel pump- I've disconnected the power to the pump. <br /><br />Any suggestions? Appreciate any and all help!<br /><br />Thanks.<br /><br />Kevin.

Re: 40hp Mariner problems.

Maybe try rebuilding the carburetor. The fact that it needs to be choked all the time is indication of a bad fuel to air ratio. It is a cheap easy job and it rules out any problems in that degree.

Re: 40hp Mariner problems.

That will be my project for tommorow then. Thanks so much for your input, I really appreciate it. Did the plugs earlier tonight, and did some work on the hull. Was waiting to hear from you motor pros!<br /><br />Thanks again.<br /><br />Kevin.<br /><br />Was wondering, the onboard 10 gallon fuel tank doesn't seem to have any kind of vent of it. Could this be a problem ?

Re: 40hp Mariner problems.

That solved it.<br /><br /><br />Anyone know how to adjust the idle on this motor? Dropping her into reverse for docking conks the engine out.

Re: 40hp Mariner problems.

hi ffullflash

did you find the idel screw on your motor?
i have the same engine i think and need to turn down my idle speed.
the only one i can find that adjusts idle is already as low as it will go.
is there another idle adjust on each of the carbs as there are a number of sring loaded screws on them?


thanks