Outdoor Power Equipment and Small Engines - 12hp briggs to much fuel

Okay, I have a 12hp briggs up flow carb engine model 300421 type 0127 on my 67 Allis Chalmers.
I have to shut off the fuel when not in use or it fills the choke/air tube and leaks out. Now, this is what I have done: put in a new kit, still leaked, checked the float, ahhaaa, had a pin hole in it and it filled just enough to sink. I opened the hole a bit, emptyed it all out and put a spot of solder on it, a very tiny spot. Felt good about that, but nooooo it still leaks. I tryed to adjust the valve seat on the float and that did no good at all. I noticed that when I take the carb apart the top of the center throat does not seal on the bottom bowl section as there is no mark on the gasket where it is sanwiched between the top and bottom(bowl section) ...help...

Are you sure that the float is fixed? I'd replace it...and the needle which is what actually seals the fuel flow if the float is working properly. The gasket seal you described isn't an issue.

I replaced the needle valve as it came in the new kit. I set the float in a bowl of gas and it floated just fine and evenly as well. The fuel shuts off with very little pressure on the float with a finger. I'm stumped :wall: I tryed finding a new float online and the measurements are to small to fit my bowl!!!

The Briggs Illustrated Parts List for this model shows the float part # to be 298514, superceded by part # 692265, any small engine shop can get it for you, or order Briggs online, current Briggs retail is $8.60.
or Google briggs float 298514
thanks,

thanks fellas I'll order the new one and give a report when I do the switch...

would a carb from a 10 hp work on the 12 hp???

Perhaps, but not necessarily. Your carburetor is part number 299551 which is no longer available but you can use a 391070, carb. I'll say that if another one you have in line looks just as yours does then it most likely would work.

Hi Spendy, I have also noticed a lot of Briggs updraft carbs with 3 screws holding the two halves together do not fit together tight & the fuel leaks from this gap when the engine runs. Almost as if the carb body is warped. I also have trouble making them not leak fuel even with new kits, floats, needle & even replacing the pressed in seats. Anyone else found this?? Thanks, Roger

Howdy Hopkins,
Mine has 4 screws holding the 2 halves together but I think they're probably the same principle. It appears that they should seal together at that center point otherwise why does the gasket go to the center and not just the outer edge, something needs to keep the gas from flowing into the throat....I don't know....

The fuel level should never get high enough to leak at that spot. The float should be shutting off fuel flow long before it gets high enough to leak at the gasket. The float is either hitting the inside of the bowl, not floating, sticking, or something to that effect, or the needle is sticking somehow. The gasket you're worried about shouldn't even be in contact with the gas except if the engine is tilted or running with gas sloshing.

thanks Cheese, thats what I wanted to here. I have the "think to hard" syndrome. I'm still gonna get that new float. Finiky little things aren't they!!!!!

Especially Briggs 2-piece Flo-Jet carburetors! Listen, if you can get the engine to run well yet it leaks when at rest, don't fight yourself over it - it gets even the best mechanics flustered - and just be sure to shut off the fuel supply at the valve under the gas tank between uses.

Hey there Puey61,
Thats what I been doin, shutin off the gas. I think it's the nature of the beast an I'll just leave well enough alone. The tractor starts on less half a spin, chugs like a workin machine, what more can ask for.....