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I recently picked up a Coleman generator with a 11HP BS engine (Engine Model 252412). It is a 1991 vintage and even had the original gen and motor manuals... It looked brand new, so I took it home. Changed the oil and checked it all out, put some gas in it and it started on the first pull. Blew a little smoke getting rid of the oil in the cylinder due to lay up. After running for about 15 mins I shut it off and it started dripping some gasoline from a hole in the bottom of the pipe that connects the air filter to the carburator inlet. Maybe a tablespoon or so... didn't leak while running. Only after shutting it off. Check the photos which identifies the hole.

Questions: Is it supposed to leak or is it supposed to have a plug in it? Does fuel leak out due to an issue with the carburator? What would fix it? Carb kit... gasket set? The manual shows the "hole" but it never identifies it or explains what it does. It does appear to be threaded but its hard to tell for sure, with all the green paint.

I attached a few files to better illustrate the issue.

schleeb said:

Questions: Is it supposed to leak or is it supposed to have a plug in it? Does fuel leak out due to an issue with the carburator? What would fix it? Carb kit... gasket set? The manual shows the "hole" but it never identifies it or explains what it does. It does appear to be threaded but its hard to tell for sure, with all the green paint.

Click to expand...

Up Draft carburetor.

No it shouldn't be leaking when the carburetor is right but area is a drain to keep things from filling up completely with fuel during a leak. The main nozzle seating to fuel bowl is leaking. The main mixture adjustment is where the main nozzle is located. It takes resurfacing the seat to stop the leak using an old nozzle with threads remove and valve grinding compound. This isn't explained in the service manual as it is later procedure that developed to save the carburetor from having to be replaced. It is not always successful but over 90% of the time it is.

This is one case where a manual fuel shut off is useful and is usually already there on the fuel tank. But when the carburetor is working right isn't needed; just a nice to have backup device.

It is also to note that the Briggs kit 694989 does not include the nozzle and must be order separately. It is in many after market kits but some these after market have a improper thread high speed adjustment fuel valve nut. I have several times over the years had to special the high speed adjustment kit because of this.

If the fuel stopped leaking after a minute or so, and then didn’t continue I would not play around with this carb at this time. Many times the viton tip on the float needle will dry up, not allowing proper seating, but will soften up when exposed to fuel. Here is a service manual for that engine. https://drive.google.com/file/d/0B6NaqjIxWV1ycG8wd0s3Z2Q2X00/view

I was thinking a common problem I run into but yes the float needle/seat could be leaking or even a bad float. The problem I referred to is one where they leak sitting and drain the fuel bowl. Usually a leak float needle/seat or bad will cause the engine to run rich during operation too.

The fuel tank is above the carb, so fuel flows by gravity from the tank to the carb. In the fuel line between the tank and carb you'll want a 1) fuel shut off valve, and 2) a fuel filter. If rust formed in the empty tank during long storage, then particles could travel to the carb. That trash can hold the float bowl valve slightly open. That would cause a dripping after the engine was shut OFF.

>> Additionally, you'll want to practice shutting OFF the fuel and allowing the engine to run until the carb is out of fuel. That's a MUCH better procedure than allowing fuel to sit in the float bowl.