Mercury 115 leaking fuel from float cover

I took my new 1983 ranger 330v with a 115 tower of power for her maiden voyage. I ran it in the yard off and on for probably over an hour to be sure it would run good before driving an hour to the lake. Well after unloading the boat I try to prime the bulb and it never got hard. I looked back and gas was pouring from under the cover. I took it off and noticed I'm leaking gas from here.



it's a little bleeder looking thing. I thought it was a screw and attempted to tighten it with no success. I ran the motor and it leaked but when I would unhook the fuel line it would stop. The engine would bog down really bad when I tried to load the boat but it idled ok. I think it must have fouled a couple plugs.

What would cause this? A stuck fuel diaphram or check valve? I also noticed with the motor fully tilted it would pour fuel from the front of the carbs.

Also is gas supposed to leak from that screw if something goes wrong or is it the culprit?

Re: Mercury 115 leaking fuel from float cover

Ok I have the carb off now. The float has a little gas in it is it supposed to? I don't see any visual trash in the bowl. I still can't find the name of the part the fuel was coming out of. I think it's some kind of vent.

I think what happend was something got stuck and let it just flood gas through it. I don't know much about carbs but my dad is supposed to help me take it apart and clean it and reinstall it. Right now I'm just trying to figure out what happend.

Re: Mercury 115 leaking fuel from float cover

I'm assuming you've got the milky-white plastic floats, since you're seeing gas inside. Definitely replace that float. Besides fuel pouring out the float cover vent jet, you'd have excess fuel dumping in the carb. Most likely the cause of your running issue.

If that's the only problem you're having, you may need to go no further than that, especially if it clears up the issue.

If you're still having problems with the carbs, recommend you pop all three float chamber covers and replace all the floats, also the carb needle/jet assy's.

You can try looking up parts at the iboats.com online store, but I don't believe they have any diagrams. www.boats.net does and has pretty good prices and reasonable shipping.

If you plan on working your own motor, it'd be a good idea to pick up a manual. A Merc factory manual is the best, but even a Seloc manual has plenty of good info on carb service.

BTW, one thing you can do to ensure survival of your motor is to disable the "Back-Drag" feature of your carbs. Part of the Back-Drag design is the vent jets installed in the float covers. The other would be the little black hose which runs from the carb throat to the float cover.

Take the hose off at the float cover, plug with a small BB or something similar and then you can plug the hose back into the float cover.

It's recommended to remove the vent jets if you can get them out. If not, it's not gonna hurt that much since the Back-Drag feature won't work if the little black hoses are plugged.

What the Back-Drag does is lean out the motor at higher speeds, for economy. The suction on the float chamber lowers atmospheric pressure inside, and this restricts fuel flow. The vent jet provides a controlled opening, i.e. a smaller jet would restrict air rushing in the float chamber and result in a leaner mix; a larger jet would restrict less air and do the opposite. Merc found out this wasn't such a good idea, leaning out an I-6 makes it prone to detonation and burnt pistons/rings. Especially with the alcohol-laden fuels we have today.

Once you get your carb issues solved, here's a couple other things you can do for your motor:

http://forums.iboats.com/showthread.php?t=168855

http://forums.iboats.com/showthread.php?t=158076

HTH & G'luck.........ed

Re: Mercury 115 leaking fuel from float cover

Thanks for the info man. I talked to my father and he also said that all my problems are probably related to the bad float. I definitly want to do the back draft delete. I don't like anything with lean and two stroke in the same sentence. I'll probably try to set the carbs and timing with the link u provided also.

Well on a positive side I wet sanded, buffed and waxed the boat today and can't believe how much better the top half of the gelcoat looks. I think I sanded off 25 years of age off of her. Lol