Carburetor leaks

JRonW

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May 8, 2014
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A 1985 Mercury 115 motor leaks gas from all three carbs at shutdown through the butterfly linkage. Carburetors have been changed out, and leaked, and rebuilt, multiple times and leak. Is there anything we are missing here. This has been going on for some time. Each time the the carbs are changed or rebuilt they leak. Anyone have any ideas?
 

midcarolina

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Jul 16, 2013
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Re: Carburetor leaks

Did you replace the floats with new ones? and set the float height?
 

JRonW

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May 8, 2014
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Re: Carburetor leaks

The floats were not changed but they were set.
 

midcarolina

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Re: Carburetor leaks

Someone else may chime in with more idea's, But I know old floats can get saturated with fuel and not work properly.....I would also verify the needle and the seat was replaced.........
 

Chris1956

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Mar 25, 2004
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Re: Carburetor leaks

+1 on change the floats. The springs rust away, the hard plastic floats crack, the foam floats dissolve.
 

JRonW

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Re: Carburetor leaks

Thanks guys. I'll check the floats. You have been most helpful.
 

MH Hawker

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Re: Carburetor leaks

Its pointless to do a carb rebuild and not replace the floats.
 

JRonW

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Re: Carburetor leaks

The floats were changed and set at rebuild. Carbs still leak. They don't leak while running, just at shutdown.
 

midcarolina

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Jul 16, 2013
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631
Re: Carburetor leaks

Then it's either the needle or seat worn allowing fuel to seep past and over fill bowl, or the float is not closing the needle at the correct fuel level.
 

Chris1956

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Mar 25, 2004
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Re: Carburetor leaks

They often leak when the motor is stopped and tilted up. If that is what you are seeing, it is normal.
 

JRonW

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May 8, 2014
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Re: Carburetor leaks

We are checking with the motor down, in a barrel, and the gas appears to be leaking from the linkage.
 

sam am I

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Jun 26, 2013
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Re: Carburetor leaks

Might ya be able to snap a few pictures? With a descent camera if ya got one, I'm curious.

Is it like just weeping(little tiny bit wet is okay) or dripping(not too normal), or like running/pouring out(fire hazard)
 
Last edited:

racerone

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Dec 28, 2013
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39,230
Re: Carburetor leaks

If throttle shafts are worn then any fuel that is past the venturi will leak out when engine stops.--Changing / adjusting floats will not fix that.---Just the nature of a carburetor with a vertical throttle shaft.
 

JRonW

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May 8, 2014
Messages
6
Re: Carburetor leaks

We ran the motor today, Tuesday May13. As I was about to take pictures to so what was going on, my father-in-law had an epiphany. But first let me tell what I saw. After running the motor for about 2 minutes, no leaks were observed. After about 1 1/2 after shutdown, I noticed some gas on the shaft of the top carb. After about 5 minutes, gas was dripping from the bottom carb shaft. A drip rate of 1 drop per 54 seconds. I feel this is significant. Now, let me tell you my father-in-law's epiphany. He has had this boat for many years and has had these leaks all that time and has fought it for 10 + years. He was standing back looking at me inspecting the leaks and notices something. Now you guys are asked not to laugh but, he notices that the boat is leaning from left to right by some inches. I feel stupid. The boat is listing to starboard by some six inches. He gets his floor jack to level the boat and it would appear only the top carb actually has a leak at the linkage shaft. The motor leaning was causing the fuel in the bowl to leak through the weep hole at the top of the bowl on all carbs. Well I guess you can laugh now, Knowing you already have, but I feel stupid for not noticing. We thank you for your help on this situation. Moral of the story, make sure the boat is level when working on the carbs.
 

Chris1956

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Mar 25, 2004
Messages
28,552
Re: Carburetor leaks

Those weep holes sound like back-drag jets. If so, fuel should not leak from them. It is likely the fuel level in the carbs is too high. So maybe the float levers are not set correctly?
 

sam am I

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Jun 26, 2013
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2,169
Re: Carburetor leaks

Concur w Chris, the fuel bowl level/s sound a bit high.
 
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