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osenga

Carb troubles

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osenga

I'm working on a 3112 it has the 12hp Briggs with the 4 bolt updraft carb. And it's leaking like crazy. Here is what I have done so far. Lower bowl is cleaned new gaskets and the upper body is brand new(out of the box) set float level. And with doing all of this it's still leaking probably would wipe a full tank out within a hour. Any ideas how to stop this. Float is good to.

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Tonyvdb

Sounds like either the float is set to high or the needle and seat are not seating good. Could be a bit of dirt got in and holding the needle off the seat?

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JJ MARSHALL

check needle & seat

what seat was in the new upper part?

make sure you got the right needle for the seat.

lot of these carbs will drip

but what you are saying is way 2 much.

good luck on finding you problem.

JJ

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powerking_one

Bryan,

A few ideas come to mind here.

Was this carb leaking and the orginal problem before the "rebuild"?

Like Tony mentions, just because the upper carb body is "new", don't assume the float valve & seat are working correctly and not leaking. Perhaps test this by putting the upper body & float assy into a small tub of water simulating a closed float condition (with fuel supply connected) and check for gas seepage from the needle/seat (gas floats on H2O).

The hi-speed jet/emulsion tube could be leaking around the tapered seat (common problem). There have been many historical posts on tricks to re-seat and burnish the tube/lower body seat surface to fix the leak.

If there was a lot of corrosion in the lower body, perhaps it is a porous leak in the lower body.

Tom (PK)

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RandyBuxton

I want to make sure I have this straight because the carb on my B10 leaks from the hole on the bottom when not running. Running, no issues. I have placed a shutoff in the gas line between the tank and the carb so that when I'm doing with the job I can stop the gas flow then just let the fuel burn up in the carb.

I've seen posts on here about placing a particular small O ring in the carb (at a specific place of course) and that stops the fuel drip. Is that for when the engine is running or not?

The inline shutoff works,, but during the break times when I just need to make a short stop it is a pain to stop the engine and have gs drip til I start up again.

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fishnwiz

You may have the wrong type needle valve in the carb. Some use a rubber tip needle and others use a metal tip needle with a rubber seat that is inserted (ring groove side down) into the needle seat. If the wrong needle is in or rubber seat is not in or upside down...you will leak excessive gas.

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RandyBuxton

Both tips and a rubber seat came with my carb kit. I did not put the rubber seat in since there was not one there before. Maybe there should have been. I presume there should be no leaking when the engine is not running, right?

quote:Originally posted by fishnwiz

You may have the wrong type needle valve in the carb. Some use a rubber tip needle and others use a metal tip needle with a rubber seat that is inserted (ring groove side down) into the needle seat. If the wrong needle is in or rubber seat is not in or upside down...you will leak excessive gas.


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