Popping through the exaust

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Skipp2Maloo

Recruit
Joined
Jul 26, 2006
Messages
4
Help.. I am new to outboards and just bought a pontoon witha 50 Merc that had sat up for several years. I drained the gas (it was dark brown) and rebuilt the carbs and had to replace one float. It starts good but pops through the exaust every now and then with a heavy miss. It will idle for awhile then the miss will kill it.
 
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Skipp2Maloo

Recruit
Joined
Jul 26, 2006
Messages
4
Re: Popping through the exaust

I changed the plugs and it did not help. I bought some SeaFoam and will try to Decarb it.
 
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eric1111

Cadet
Joined
Jul 7, 2006
Messages
21
Re: Popping through the exaust

check to see if the fuel bulb gets hard and may consider rebuilding fuel pump. diaphram may be bad in it. bad gas can cause lots of probloms
 
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eric1111

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Joined
Jul 7, 2006
Messages
21
Re: Popping through the exaust

check compression and make sure you are firing on all cylinder
 
Texasmark

Texasmark

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Joined
Dec 20, 2005
Messages
14,558
Re: Popping through the exaust

Yeah on the sea foam. Should fix you up. Then run some in every tankful. I think they recommend 4 oz to 10 gal for maint purposes.

If the rings are stuck the compression test may fail. You may want to wait till you have decarbed it to make the comp. test.

Mark
 
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Skipp2Maloo

Recruit
Joined
Jul 26, 2006
Messages
4
Re: Popping through the exaust

Compresion is 110 to 112 on a 3 cyl. DeCarb seemed to help some. Fuel bulb feels firm. Took it to the lake this weekend and tinkered some more with timing and carbs. Idle is better now. May run good for a few min. then RPM drops from 5K to 3K. Pumping bulb does not help. Seems to run better on a full tank may run good for an hour. When it does bog down with a full tank I shut off for a min. and it will perk back up. When it gets to half tank it is sure going to mess up and will not rev higher than 3K. Changed hose and bulb that did not help.
 
Texasmark

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,558
Re: Popping through the exaust

Pull out your fuel outlet in the tank and see if the screen on it is clean. The only thing I can think of is the fuel tank is putting very slight pressure on the fuel (when full) and that helps it to move correctly. Interesting that pumping bulb doesn't help.

Additionally check the fuel routing to the carbs and see if there is a fuel filter on the engine. If so, change it.

Lastly maybe a new fuel pump is in order and a new Quicksilver, not aftermarket, bulb.

Drop the bowl on a carb and see if there is any crud in it.

Mark
 
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