Re: 1991 50HP Force "jerking"
Plugs are way overdue for changing. They are the correct plugs, and should be "gapless" type, with no adjustment. Change thjem every 80 hours of operation, and run a can of "decarb cleaner" thru this motor just before changing the plugs.<br />This stuff is available at most marine stores, or here online. It's expensive, but needed.<br />If the plugs were tarry and wet, you can return the setting on the mixture screw back to where it was. Just don't pull a plug, and find it dry or new-looking. Dry means inadequate lubrication, new-looking means steam-cleaned by water injestion. So it's best to error on ajustment on the rich (or wet) side. Your plugs will foul earlier, but your internals will be like new...It's how many 30year old outboards survived, and your can be one of them someday.<br /><br />You may be new to boating, but you came to the right place, and you have the right approach....Preventive maintainence. These are reliable motors, but need lots of care,(not that they all don't but) being an older design, it's expected.<br />Also ,the shop manual is a must. This motor was not designed to operate on modern fuel formulations, and alchohol-enhanced fuels devour rubber (found in the carb and the fuel pump diaphram is rubber)...But those parts are cheap.<br />Fuel pump diaphram is good for about 2 seasons, and takes about 15 minutes to change out, when the time comes.<br />Impeller/thermostat changes should be every other season whether they fail or not. When an impeller fails, the outboard motor will often 'injests' the pieces....Not good. The old one will look fine whewn you pull it, they allways do-- until they have failed. If it fails on the water, you are lucky to salvage the motor.<br />And welcome to iboats
