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post #1 of 16 Old 03-27-2019, 01:15 PM Thread Starter
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carb overflow

i have a john deere 11 with a 12hp briggs motor and it floods the motor with gas when i shut it off so i put a shut off valve in it but by the time i get to it it has dumped gas into the crankcase. is this a problem with these carbs or do i nreed to rebuild the carb.and will that help?
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post #2 of 16 Old 03-27-2019, 04:12 PM
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i have a john deere 11 with a 12hp briggs motor and it floods the motor with gas when i shut it off so i put a shut off valve in it but by the time i get to it it has dumped gas into the crankcase. is this a problem with these carbs or do i nreed to rebuild the carb.and will that help?
Clean or rebuild the carb. Most likely problem is something is either stuck in the needle/seat or one or the other has wear or damage. You could conceivably have a "sunk" float also, but that's pretty uncommon. If the needle can't close the passage, fuel will just continue to flow until the tank is empty and/or the crankcase is full.
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post #3 of 16 Old 03-27-2019, 10:52 PM
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Re: carb overflow

I would bet on a defective float or one that is misadjusted. An easy way to get around it is to put the fuel shutoff valve so you can reach it from your seat and turn it off before you turn the ignition off. That's effectively what Kawasaki did with their solenoid fuel cutoff valve when you turn the ignition off.
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post #4 of 16 Old 04-07-2019, 12:15 AM Thread Starter
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Re: carb overflow

i got one on there now. now if i can get the motor to turn over. when it rains it pours.
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post #5 of 16 Old 04-07-2019, 05:53 PM
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Re: carb overflow

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Originally Posted by green dream machine View Post
i got one on there now. now if i can get the motor to turn over. when it rains it pours.
pull the spark plug(s). If it was overflowing for a long time, you might have cylinders full of gas. Change the oil too, as some of the gas will have gotten down into the oil.

Ryan

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post #6 of 16 Old 04-07-2019, 09:15 PM Thread Starter
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Re: carb overflow

that's the first thing i did it has new oil in it and a new spark plug ready to go. i am going to clean the battery cables and try to charge it. i think the battery is toast. it sat all winter without a charge.
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post #7 of 16 Old 04-07-2019, 09:26 PM
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Re: carb overflow

I had a similar issue, actually the same issue, with a Briggs engine 2 months ago. If the float is not working or the needle valve is stuck open fuel will continue to flow. And not only will it continue to flow, but because of the way most Briggs small carburetors are designed, with a vent to the crankcase, the fuel will fill the crankcase mixing with the oil.

The first clue will be very large clouds of smoke if you can get it started. A fuel shutoff is not the cure. Replace the carb and replace the oil. Keep checking the oil for about a month until you are sure that the problem is resolved.
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post #8 of 16 Old 04-08-2019, 12:14 AM Thread Starter
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Re: carb overflow

should i rebuild the old carb or just buy a new one?
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post #9 of 16 Old 04-08-2019, 01:13 AM
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If you are competent enough to rebuild the old one, I'd just do that.
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post #10 of 16 Old 04-08-2019, 03:04 AM
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Re: carb overflow

First, shut off the fuel and run the motor until the carb is empty and the engine stops.
Then open the fuel and start normally.
9 times out of 10, that solves the problem.
If that doesn't work, you need to take the carb apart and clean the needle/seat.
I've seen many illustrations in books of how a worn out needle looks; but never seen a worn out needle in my life. Just clean it out with compressed air or carb cleaner.

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post #11 of 16 Old 04-08-2019, 07:08 AM
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Re: carb overflow

The OP can go crazy with a rebuild, due to what is probably a gummed up carb, or buy a carb on Amazon for about $50 or less. The problem will be that he will never clear all of the passages of gum or hardened residue. The last B&S carb I bought was for a generator and it cost $31. That was after I wasted my time and the cost of a rebuild kit. So the OP can attempt to clean the carb, but after that I wouldn't waste my time any further.
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post #12 of 16 Old 04-08-2019, 10:11 AM
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I've never seen a carb that was so bad it couldn't be cleaned. And I've torn apart hundreds. Regarding wear on the needle and/or seat - I haven't seen that either. But it's not wear that needs to be worried about, it's corrosion/oxidation.

If even a little of the tapered part of the needle corrodes away in the right spot it will not seal fluid-tight. The other issue I commonly see is a bit of oxidation sticking the needle open - usually this happens where the body of the needle is supposed to slide freely inside the bore in the carb and they get sort of "glued" together. The problem with just cleaning in that situation is that once the corrosion has happened once, it comes back easier and faster the next time. Best to just get the rebuild kit. If you can find a carb that you're SURE is new for a good price that will work too. If you're buying a rebuilt carb you might just as well rebuild your own.

Edit: I should have more properly said I haven't seen needle/seat wear that actually caused leakage. I've definitely seen needles with pretty big grooves worn in them. The thing is, they seem to wear with the seat into a perfect match, so they rarely leak much even when they're pretty worn.

Last edited by eKretz; 04-08-2019 at 12:02 PM.
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post #13 of 16 Old 04-17-2019, 07:01 AM
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Re: carb overflow

I've worked on small engines since the early 60's and have seen plenty of carburetors not worth the effort to rebuild. Why charge the customer for a rebuild when you can supply a new carb for almost, and today for even less than, the cost of a rebuild. Time is money son, to both you, the customer, or even just to yourself.
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post #14 of 16 Old 04-17-2019, 07:50 AM
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Re: carb overflow

I too have worked on small engines since the early 60's and have seen worn needle and seats as well as carbs too far gone to rebuild. It's rare but more likely now days due to the ethanol in our gas and the low expectations of manufactured products. Young and old alike don't expect their purchases to last anymore so they just don't do the maintenance. Is it advertising and marketing telling you new is better? I'd guess. Now can anyone explain the phrase I heard the other day? My young neighbor said her friend was getting divorced, no big deal, it was just a "starter marriage!"

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post #15 of 16 Old 04-17-2019, 05:02 PM
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Speaking for myself, the new carbs aren't the same as the oem. I'll take an old oem carb any day over any new made in China crap. YMMV.
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