Mallard1100

2003 Merc 90hp fuel leak

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Hi gents, I have a fuel leak on my 2003 90hp 4 stroke Merc that has me scratching my head here. Heres, the timeline of events and some details. The leak seems to be coming from the bottom carb fuel line ( of course hardest to see and get at). It runs down the line and drips right at that point.

In November 2019 the leak started. Came back to the boat a month later and run the engine on muffs for 20 mins. Zero leaks.

February 2020, take the boat out and run the engine for over an hour at different rpms. Zero leak. 

March 2020, first trip on the water for stripers. Run the engine for 6 plus hours. Zero leak. 

April 4th, 2020, take the boat back out and I have gas leaking again.

No performance issues at all. Motor runs great aside from this.

What gives!? Maybe something sticking in the carb or cracked fuel line? I attached some pictures of the carbs and the bottom carb fuel line where the fuel is running down (right below the intake manifold) It’s source seems to be where it connects into the carb. Could the fuel line have stretched at that point and start to leak or crack? I have also read a few things about these older grey merc fuel lines breaking down? These like are most certainly originals and at this point 17 years old.

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While your at it you should replace them all as you will be chasing this for some time. Also, the ethanol is eating away at the lining of the old hoses and gues where all the degree goes.

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45 mins ago, 757saltwater said:

Replace all. Btw your missing a clamp on the hose in the second picture.  One facing down on the t. 

I noticed that as well. Thanks. Seems the mech that worked on the this motor with the previous owner had a serious lack of attention to detail. 

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