1966 Johnson 33hp carb problem

acdc96

Chief Petty Officer
Joined
Apr 23, 2013
Messages
412
Hello all,
Lately the carb float seems to be sticking fully open and dumping fuel out the Venturi on my 33hp Johnson.
It's been doing it more and more often at the oddest of times underway for the most part. I've cleaned the carb several times and it all functions properly and very clean. I've tried every trick of getting the float to work but it just randomly goes back to normal.
Anyone experience this? Or Any ideas on what to do?
 

tomhath

Master Chief Petty Officer
Joined
Dec 5, 2007
Messages
814
Sticking open sounds like there might be a burr or something like that on the pin that the float swivels on, or the float itself is slightly bent and jamming. Maybe it's time for a rebuild kit.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Check the bowl vent--all the way through. Mud daubers just can't stand to see that open hole and feel compelled to jam it full of dirt. The vent is that big hole next to the main air intake on the carburetor.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Does your float float? Those old cork floats have a habit of soaking up fuel to the point where they're more like sinks than floats.
 

acdc96

Chief Petty Officer
Joined
Apr 23, 2013
Messages
412
I took the carb off the motor this morning and completely tore it down. I haven't checked the float to see if it floats, but the varnish seems to be in very good condition (yellow varnish).
The vent hole is clean and so is the rest of the carb.
The odd thing that confuses me is I can understand it coming out the vent hole, but it's also dumps fuel out of The jet in the carb, causing it to run extremely rich and cut out.
I purchased another rebuild kit and it will be here by the end of the week.
Is the float boat suppose to be a tight fit on the carb body?
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Some aftermarket carb kits have a bowl gasket that is slightly too large, causing the float to hang up on it and not drop back down.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
If I may over simplify, think of it this way: If you take an empty Coke bottle and turn it upside down and stick it in the water, it won't fill up because the air can't get out of the bottle. Same way with your carburetor bowl, if the air can't get out, it won't fill up. And if it won't fill up, it cannot raise the float to shut off the fuel. So, what happens? Like any liquid, it seeks its own level. That means instead of filling the bowl and shutting off, it rises in the venturi nozzle and dumps out big time.

Learned this stuff the hard way.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
In addition to floats not floating, they can sometimes be installed upside down. The nozzle comes out, and needs to have the little holes cleaned -- just like those up at the top under the domed fitting. I disassemble them and soak all metal parts in lacquer thinner, then use a piece of thin wire in every opening -- finally spray out every opening with carb spray, and check to see all passages are open.

The choke flapper needs to fully open and close -- also worth checking. Soak the top and bottom of the carb after disassembly, leaving throttle and choke linkages in place. A little WD-40 on the linkages is a good idea after reassembly.
 
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