Thread: Merc 50HP 2-Stroke Running Rough

Originally Posted by MNCrapps

The boat has a 13 gallon built in tank. I did run 2 cans of sea foam through it before I discovered the fuel hose issue but not since rebuilding the fuel pump. I will try your suggestion. I should also mention that i have an extremely difficult time adding gas to the tank. The pump kicks off on me repeatedly and gas spits back. I think a trap has formed in the vent line.
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I had this problem on a 94 tracker Pro-V. It developed once it was a few years old and took forever to finally figure it out.
Once it developed I figured something had to be blocking the fuel fill some how and I looked down in the tank and saw nothing. I ran the fuel tank really low one day and when I got home I pulled the 17 gallon tank and same as before I saw nothing. For a few years I still lived with it. One day I decided to look down the fuel fill hole on a sunny day and with that sun shinning straight down the fuel fill hole I finally saw the problem. It was a piece of the fill cap that had come unscrewed and blocked the fill tube. In the fill cap there is a small, maybe quarter size piece of plastic that screws into the center (on the inside) of the cap. I believe that part is there because of the venting of the tank so I can't get rid of it but every time I fill that tank I check to make sure it's still there and still sitting snug in cap.

I bet I looked down that fuel fill hole 20 times over the years that the piece was in there before I saw it. With the part being black and looking down into a black hole it took that sun sitting directly overhead before I finally saw it.
I hope this helps.