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Lawn Mower carburetor/gas leak problem

Posted by neeboy74 MO (My Page) on
Sat, Nov 17, 07 at 16:44

Hello to all:

I found this forum while searching for an answer to my lawn mower conundrum:

My landlandy's Craftsman lawnmower appears to be leaking gas out the carburetor; I assume this because gas is leaking out the primer bulb, and the air filter gets soaked with gas when I try to fill it up. The mower will not start, period.

I have searched on the Web and found much discussion about this kind of (seemingly common) problem at this forum. Here are the vital stats on my mower:

Craftsman model: 917.378361
Briggs & Stratton engine model: 123K00 series

The answers I have read on this forum involve replacing/removing and cleaning the carburetor. This model mower DOES have the brass nut on the bottom of the carb. Can I replace just the bottom of the carb as I have read in the posts about the Techumseh engine, or do I need to replace the ENTIRE Briggs/Strat carb? Thanks in advance for any help!


Follow-Up Postings:

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RE: Lawn Mower carburetor/gas leak problem

  • Posted by baymee LehighValleyPA (My Page) on
    Sat, Nov 17, 07 at 20:51

I would replace the primer bulb first if it's torn or leaking anywhere except the center hole of the bulb. I don't know if yours has a vented bulb or not. If that doesn't fix it, then remove the float bowl by removing the bowl nut and see if the float stops gas flow with light finger pressure. It might also be a leaking needle seat.


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RE: Lawn Mower carburetor/gas leak problem

Most likely there is a spec of crud lodged in the carb needle/seat. Remove the float & needle, let the fuel line flush things out a bit and reinstall.

Also check the oil for the presence of fuel and change it if it has gas in it.


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RE: Lawn Mower carburetor/gas leak problem

Bill has it right. Fuel should never get to the primer on a 12 cid Briggs. The primer pushes air. The inlet needle is not sealing. Whether this is just a small spec that will flush easily or varnish requiring rebuilding will only be known by taking the carb apart.


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