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JP10

Need some engine assistance

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JP10
I was starting up the B112 today and noticed it was having a harder time than usual gettin started. It usually starts with choke only then you can back it off, but this time fuel was just dripping out of the bottom of the carb. Finally got it started and it would run fine with no choke for about 1-2 minutes then start sucking for fuel almost to the point of killing itself then it would snap out of it and run fine again for 1-2 minutes and continue this cycle. When it would want to die black smoke would come out of the muffler then run fine again without any smoke. I'm thinking I need to rebuild the carb and also install an in line fuel filter. Perhaps water or dirt is in the fuel, I don't know. It also may be a compression problem, perhaps a new head gasket would help. I'm just troubleshooting off the top of my head but any suggestions from you guys would be much appreciated. Thanks, J-P

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HubbardRA
first of all, nearly all of these B/S updraft carbs will leak some. You need to have a fuel shutoff in the gas line, and shut it off when not being used. This will prevent the engine from being flooded when you try to start it. The way you described yours, it appears that the leak is more than the amount of fuel being used by the engine. Usually this means that you need a new float needle. It could also be a leak at the seating surface of the emulsion tube, or your float could be leaking and slowly sinking. In any of these situations, you will have to take the carb apart to find the problem and fix it.

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dentwizz
My guess is the float/needle may be binding/sticking. Agreed, rebuild and replace the rubber components. I fully agree with Hub, I put a little 1/4 turn fuel valve on the fuel line where it exits the chassis to turn it off when not in use. I have noticed a large decrease in fuel fumes when it's in the garage also. People often assume contaminated fuel, but by my experience the briggs engines are very contaminant resistant. Water is another story, but you have demonstrated that it is flammable enough to run. A runs-a-while then quits and runs-a-while is an indication of the carb bowl being sucked dry(insufficient or obstructed supply). This would be from a needle that is stuck in the up position. Conversely, a flooding bowl would be a needle not seating. The head gasket will be evidenced by a streaking line around the head seam where compression was leaking. The chances are, it is fuel.

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JP10
I figured it would have to do with the carb, a bad float or needle sticking as you described. I just wanted to make sure I was on the right track. I'll just rebuild the carb and hopefully that will fix it. By the way, all my tractors already have fuel shut off valves and I am aware that these carbs leak. This one was just leaking like a fountain. Thanks

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