1979 50 hp merc

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imported_skraps

Seaman
Joined
Feb 23, 2007
Messages
64
Engine runs fine when on muffs, but wont accelerate when in water. Just idles smooth and when acceelerated just dies. This just happened sudenly when out on the lake for a day. Stopped to fish and when restarted it would only idle back to the boat ramp. Runs on all four cylinders when at idle. Four coil type ign.
 
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S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: 1979 50 hp merc

Usually those symtoms indicate a fuel supply problem.Could be a weak pump.
see if squeezing the primer bulb helps.See if a little choke helps.
 
Nos4r2

Nos4r2

Lieutenant Commander
Joined
Dec 12, 2004
Messages
1,533
Re: 1979 50 hp merc

Yep. Clean the carbs out too. Water or crud in the float bowls will cause this as well.
 
JB

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: 1979 50 hp merc

"Runs on all four cylinders when at idle."

How did you confirm this? Checking spark does not confirm that a cylinder is making power. Any multicylinder 2 stroke seems fine when not under load, even on half its cylinders.

It does sound like one carb has clogged medium and/or high speed jet.
 
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imported_skraps

Seaman
Joined
Feb 23, 2007
Messages
64
Re: 1979 50 hp merc

The way i comfirmed that it idles on four cylinders is by pulling each plug wire while its running. Also choking or pumping the bulb has no efect on the running. Choke it and it dies.
 
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