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Discussion Starter #1
I just rebuilt a Briggs opposed twin, and in the process, cleaned and put new gaskets in the carb & fuel pump. The engine fired right up, but gas was jetting out of some opening in the carb body I’m not able to identify. It’s the opening just above and behind the green fuel line clamp in the photo. What is this opening? And how is it suddenly now open after a simple cleaning? Did I damage a seal when using compressed air? More to the point, how to fix it? It pulses gas, so I’m guessing it ties into the fuel pump circuit for some reason.

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Could you have missed putting in a gasket, or O ring....or just not tightened it enough?...it's kind of small for a welch plug to be missing from it
 

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I think Mark hit it on the head. Looking at mine, there is a plug in that hole. Its pretty deep in there - did you happen to dislodge it?
 

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Discussion Starter #5
Looking at mine, there is a plug in that hole. Its pretty deep in there - did you happen to dislodge it?
Yeah, I was thinking there must've been a plug in there I dislodged somehow. I'll have to get inside it. Thanks. I'll keep you posted.
 

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Discussion Starter #6 (Edited)
An update: As a PSA to anyone who might find it interesting or helpful, the answer to my original question is that hole is a relief port - if the bowel fills too much, excess gas is vented out. No gasket, ring or plug was blown out or missed during the rebuild.

The real problem turned out not to be that vent, though: I figured since I pre-filled the bowel with gas before I screwed on the top half of the carb, I likely overfilled it, and just needed to run the engine to get it to self-correct. When I ran the engine, though, gas kept shooting out - definitely not self-correcting - and it was quickly obvious the gas wasn’t coming from that vent. It was coming from the gasket. Turns out I wasn’t paying attention when I put the carb together, and installed the gasket backwards, so there was a free shot out from the fuel pump circuit. My bad :rolleyes:. I flipped the gasket and I'll re-install the carb, so I don’t expect any more issues with it.

Thanks for the input, folks.
 

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One of the B&S pump diagrams shows the 'stack' of parts incorrectly. If you assemble in the order shown, it will not work. I do not remember which.
tom
 
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