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Carb leaking gas on B&S 6.75 mower

Posted by mtbstuff (My Page) on
Wed, Jun 4, 14 at 10:14

I have a Polan Pro mower with a 6.75 B&S motor.
It was running fine until last week when it would sometimes leak gas out of the carb throat.'s the float, needle or seat, right?

I replaced all of the well as cleaned the main jet and gave all the passages a blast of carb cleaner. Also pulled the fuel line and gave that a blast.

Bolted it back up and all was fine. Mowed the lawn. When I shut it off...fuel leaked again!

What am I missing here???

Follow-Up Postings:

RE: Carb leaking gas on B&S 6.75 mower

It is very intermittent.
It sat all last night without leaking.
It then leaked at some point this morning.
I have not touched it.

Also...everything was very clean inside when I took it apart.

I am stumped!

RE: Carb leaking gas on B&S 6.75 mower

I have had the same experience, twice. The cause of the first problem was a damaged seat. Gas was slowly getting past it and flooding the carb. The seat was only 2 years old and it was cracked on the grooved side. The second time on another piece of equipment with a 6.5 HP Briggs, I suspect dirt particles from either the gas tank or crumbling inside the fuel line . This caused an intermittent clogging and flooding much more severe than the damaged seat. The only other thing I can suggest is make sure the seat is pushed all the way down ( groove side down ) I seem to recall instructions saying to use a drill bit flat end to push the seat down.

RE: Carb leaking gas on B&S 6.75 mower

Is it possible to install a manual fuel shut off valve between the gas tank and the carburetor. It sounds like the leak is only causing a problem during storage. A shut off valve, opened for use and closed for storage would resolve the problem, if there was room to install one.

RE: Carb leaking gas on B&S 6.75 mower

  • Posted by baymee LehighValleyPA (My Page) on
    Thu, Jun 5, 14 at 14:46

I also had a similar problem and the replacement seat was bad too! 2nd one worked.

RE: Carb leaking gas on B&S 6.75 mower

Remember if you get a new seat or remove there is a up and down on the seat installation. The ring on the end goes to the carburetor base not the needle.

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