Why do Mercury outboards leak fuel?

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Mercury outboards tend to leak fuel if the fuel lines are not disconnected after every use and the motor is tilted up in trailering position. I am not used to having to remove the fuel line at the motor connection to prevent this because I have never had an outboard that did this before. My 25XD does this as well as the 50 horse 2 stroke. the only two Mercurys that I have ever owned. I replaced a leaky fuel line last week and today I found fuel dripping from the handle of the quick disconnect at the front of the motor.
 

Charlie61

Petty Officer 1st Class
Joined
Jul 27, 2011
Messages
253
Re: Why do Mercury outboards leak fuel?

I think it likly for O-ring in the disconnect is bad, do you try runing the engine after you disconnect so the gas dose not build up pressor. it could also be a bad check vale at fuel pump. what year.?>
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: Why do Mercury outboards leak fuel?

I hope the oring in the brand new gas line disconnect isn't bad. I think the pressure is built up in the gas tank because of the hot weather we have had lately so I unscrew the gas cap to relieve it. The 50 horse is a 1985-86 and the 25XD is a 1984. Just seems odd that they will both leak fuel if the hoses aren't disconnected.
 

Charlie61

Petty Officer 1st Class
Joined
Jul 27, 2011
Messages
253
Re: Why do Mercury outboards leak fuel?

if you look at disconnet on motor the pin with holes in it also thats a pin at the end of it , this is conpressed when conneted. the pin is like a shut off vale inside the disconnet. it could have something in it ,so it will not set right or the inner spring is not closeing to all the way. or just need replaced
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: Why do Mercury outboards leak fuel?

I installed the brand new fuel line to the tank and ran the boat a couple of times. After that I disconnected from the motor and let it hang in the motor well. I loosened the gas cap to relieve pressure because of the heat on the hot days. After smelling fuel again I found that the quick connect on the end of the hose had a bluish foamy coating and that it was turning to fuel as it melted and dripping into the motor well. I had a Johnson motor for decades and never had problems with fuel trying to leak like I have with the Mercury. One reason might be because Johnson fuel hoses disconnect from the tank as well as the from the motor when they are not in use. I think that is what is needed an I will install a quick disconnect from the fuel tank.
 
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