1979 50Hp Mercury loss of power

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dbueffel

Recruit
Joined
Sep 7, 2007
Messages
2
OK, I am new to boating. I have a 1979 Mercury 50HP outboard that will idle fine and run at top speed for the first 10 minutes then will start to bog hard at anything greater than 1/2 throttle. I pulled the plugs and replaced them as they had serious carbon deposits on them. The fuel is new mixed 50:1 and the vent cap is open.

I looked at the carbs today when I got home after trying the new plugs and both barrels are moving.

Any suggestion son what to look for next. Not quite sure the motor will run great for 10 minutes and then act up.

Any help would be appreciated.

David
 
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davebad22

Seaman Apprentice
Joined
Sep 11, 2006
Messages
30
Re: 1979 50Hp Mercury loss of power

As the motor starts to bog down, have some squeeze the primer bulb to force fuel into the system. If the motor picks back up then you know the problem lies in the fuel system. Check fuel lines for leaks, rebuild fuel pump. I have a '82 40hp. The diaphragm on my fuel pump got stiff and wouldn't push enough fuel to run at WOT. (wide open throttle) Motor would run fine all day long at 3/4 throttle but would start to bog down after about a minute at WOT.

Good Luck
 
S

saltfisher

Petty Officer 2nd Class
Joined
Aug 22, 2007
Messages
111
Re: 1979 50Hp Mercury loss of power

I sort of have the same problem. I have a 150 merc 1988. It runs good anything 3/4 throttle and less, but after about 20 seconds at WOT it will feel like im lifting back on the throttle, and if i accually dont back off the thottle to match my speed, it will come to a stop and shut off. Then it will be hard to start back up. Almost like its flooded. I may be pushing to much fuel, but dont know if thats possable. It runs fine if i run WOT in short bursts and then back off to 3/4 throttle. is this what yours is doing?
 
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cochran226

Recruit
Joined
Oct 17, 2010
Messages
1
Re: 1979 50Hp Mercury loss of power

What turned out to be the problem? I'm having the same problem.
 
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