1998 Fuel issues??

[Slowerthnyou99]

I just purchase a boat with a 1998 Force by Mercury engine. The engine ran fine on ear muffs, but when placed in lake it would not even crank. After getting it back home, I put it on ear muffs and took off the hood. With the engine at idle there is fuel coming out of both sides of the top carburetor. When I raise the RPM the top hole begins to spray fuel with a decent stream and engine runs pretty rough breaking up. If I back down to idle to quickly it will stall most of the time. Pulled plugs which were all wet an oily. After cleaning plugs engine fires right up and will rev freely and clean with out breaking up. After a few seconds of cycling rpm it begins to break up and run bad again leaving plugs wet again. The fuel out of the carburetor is consistent and always present. I included pictures of the 2 holes that are leaking fuel and can also upload a video of an at idle scenario. Also owner put in NGK plugs that do not have electrodes? Never used these before...

Please point me in the right direction, this is my first boat and Im getting stressed out pretty badly!!! Thanks for any and all help.

 

[Slowerthnyou99]

Re: 1998 Fuel issues??

Well, I am going to pull this particular carb off tomorrow and drop the bowl. After some extra research I am thinking I may have a stuck float that may be sunk, or the needle is not seating completley allowing extra fuel to be dumped out of the vents. As for the mystical spark plugs, apparently they are what is called for in this Thunderbolt ignition system on this year. If there is anything else I should check for let me know please. I will also evaluate all of the fuel lines and zip tie connections to insure there is not air getting in....:facepalm:

 

[Slowerthnyou99]

Re: 1998 Fuel issues??

Sorry for so many post, but as I gather info I am posting. I went through the receipts that I have for recent maint. There was a carb gasket kit for all three carbs purchased, and 3 inlet jets purchased. If this helps any theories here... Im guessing there was an issue prior to the sale that they "thought" they were addressing but Im still stuck with the problem.

 

[Jiggz]

Re: 1998 Fuel issues??

The fuel spraying out of the atmospheric vent is indication of a faulty float or damaged float needle valve. The vent hole is designed to exhaust oversupply of fuel in case of faulty float or float valve. As for the plugs being too wet, make sure the fuel/air mixture valve is set 1 turn or 1 1/8 turn from lightly seated.

 

[Slowerthnyou99]

Re: 1998 Fuel issues??

I am almost positive the fuel/air mixture is off as they have the carb marked 1 1/2 next to the brass screw pictured above...

 

[Slowerthnyou99]

Re: 1998 Fuel issues??

Alright, I worked on the carbs some tonight. Here is what I found. After pulling bowl of top carb, no matter how high i pushed the float it never seated the needle. I adjusted so when flipped upside down bottom of carb was left with flat surface of carb. Is this correct? I did this on all carbs as they were all different. Verified that needle was seating and sealing. With doing this top vent next to idle mixture screw (shown in second picture) has stopped leaking completely. But, the vent hole in the first picture continues to leak continuously. The small hole just above the fuel bowl. What should I do next? Seems to be running smoother and revving fast now.

Thanks