Gas bubbling out of top vent hole on carburetor

[fishr2eat]

I recently purchased a boat with a 1985 Force 125 h.p. outboard. The motor had not been run in 5 years so I put fresh gas in it and replaced the impeller and thermostat as a precautionary measure and headed to the lake for a test run. I noticed at high speeds some gas bubbled out of the top vent hole of each carburetor. If I backed off the throttle it stopped and then if I opened the throttle back up the gas would bubble out again. Is this normal and if it is what would be a normal amount of gas to come out? I have read up on this some and it seems that it's either normal for this motor or there is a float/needle problem? Can anyone advise me if this is ok or should I be troubleshooting something, and if so what?

Thanks in advance.

 

[pnwboat]

Re: Gas bubbling out of top vent hole on carburetor

Sure sounds like the needle valves may not be shutting off the fuel supply when the bowls fill up with gas. With the motor shut off and level in the normal running position, squeeze the primer bulb 4 or 5 times. It should get firm. If it does not get firm and gas starts coming out of the vent holes in the carbs, then you have a bad needle valve(s), debris in the carburetor preventing the needle valves from closing, or the float level is set too high.

 

[fishr2eat]

Re: Gas bubbling out of top vent hole on carburetor

Thank you, pnwboat, I will check that out tonight when I get home.

 

[Jiggz]

Re: Gas bubbling out of top vent hole on carburetor

Ditto on PNW's diagnosis. With the motor not ran in 5 years, the most prudent thing to do now is to clean both carbs at least with their floats and inlet ports. And this can simply be accomplished by removing the bowls and shooting them with carb cleaners including the jets, needle and its port.

 

[fishr2eat]

Just wanted to follow up in case anyone has the same problem that I had and needs a solution. I wound up needing to replace the seats for the fuel inlet needles. The part # FK10107 is no longer available so someone suggested I try a Briggs and Stratton part # 398188 and it worked. Thanks!