1979 6hp Evinrude Power Loss in Gear & w/ Cover On

[river_rat1971]

I have been checking out several similar posts and it seems I have two problems that could be almost anything, but maybe together they mean something.

First, the motor wants to stall when I put the cover on. Really quickly (10 seconds) it will really lose power. Not a problem if I take off. Nothing pinching. Think I might have an exhaust problem, possibly leaking gasket. I can't tell which one. Tried soapy water without much luck.

Second, it loses rpms in gear. Revs high in a bucket in N, but punks out in gear.

Checked both plugs with a tester and both seemed fine. Compression check showed 42 in one and almost 40 in the other consistently. Seemed low but the threads say that the proximity to each other is most important.

The carb on this model doesn't really have much to adjust.

Again, I know much of this has been covered many times in many posts but I have seen a variety answers that would cause me to rebuild the whole motor. I haven't seen anyone report on both of these problems. Thanks in advance.

[tashasdaddy]

1st you have an exhaust leak, from the lower unit, to the power head, it does not like breathing exhaust, that the oxygen, has been burnt. it has to have oxygen for combustion.

i would check the compression with another tester, remove the plugs, and pull it thru 6 times each cylinder. 40 is extremely low. have you cleaned and rebuilt your carb?
you have adjustable low speed jet, and a fixed high speed jet behind the drain screw of the bowl. http://forums.iboats.com/engine-frequently-asked-questions-faq/carb-cleaning-instructions-244013.html
after cleaning, follow these directions. (Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.