1985 Mercury 75 HP Stalling Under Load

Gutem

Recruit
Joined
Sep 17, 2012
Messages
1
Boat sat out for 3 years (Wisconsin), I mixed a 3 gal of gas at 50:1, topped off the lower unit oil, put the muffs on it and it fired right up with only a 1/4 turn of the key. Motor sounded great. Put it in the water it shifted into gear smoothly, I ran it across the lake at full throttle s and back (30 min) with no problems.

It sat for two weeks and I noticed oil coming out of a hole above and to the front of the upper oil screw. There are two holes, one above the upper oil screw and the other forward of the first hole. I spoke to a mechanic and was told that I possibly overfilled the lower unit.

Two weeks later when my brother went to take the boat out, he mixed more gas and forgot to vent gas tank, pumped the bulb and tried to start, motor would not start right away. (He forgot to push the button in the throttle so to reeve the motor up), when he did get boat running he idled it out and when he floored it, the motor would just die. I figured he flooded it because thought he pumped the ball too much. I replaced the spark plugs, muffed it again and it started with no problem, but when we took it out it did the same when we floored it, it would die. Also I don't know if this matters any but the steering cable seemed to be a little stiff the second time out as well. Any help would be greatly appreciated.
 
Last edited:

BatDaddy1887

Chief Petty Officer
Joined
Jan 18, 2009
Messages
463
Re: 1985 Mercury 75 HP Stalling Under Load

Welcome aboard! Doesn't it always seem to be the carburetor(s) in this type of situation? There are many posts on this forum that deal with that issue and most of the time it comes down to cleaning the carbs and replacing needles and floats. It is also very easy to rebuild your fuel pump...takes less than 20 min. You've changed the spark plugs and that was a good start, so hopefully it is your fuel delivery system and not your electrical system (coils, trigger, stator) or compression.

Tip: Use half-a-can of Seafoam in your gas tank every few tank-fulls.
 
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