Toro 518 ZR leaking fuel

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Old 01-15-19, 12:32 PM
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Toro 518 ZR leaking fuel

Just acquired a Toro snowblower (model 38472) from my wife's cousin. Her husband had passed away 2 years ago, it was in her garage but she's too old to use it so wanted it to go to a good home. It had been purchased new Winter 2016 and used that year, then stored properly (fuel had been drained etc, her husband had been a mechanic). He died March 2017.

I got it home, changed the oil, added fuel, primed it twice and it started on the first pull. Ran pretty well, with some minor surging and a little popping.

Figured the carb might be a little gummed up, added 3 oz of Seafoam to the gas (approx 1.25 quarts of ethanol-free 91) and ran it for a while. Let it sit overnight, next morning there was a smell of gas and a small damp spot directly below the carb.

The gas is definitely coming from the overflow vent on the carb. Very slow drip rate, maybe one drop every couple minutes. My best guess is that the float needle is not quite sealing and allowing a little gas to get by. When looking at the Toro carburetor rebuild kit (part # 119-1988) 2 things stick out. The needle appears to have a rubber or plastic tip, and there does not appear to be a replacement needle seat included. So I guess the needle seat is machined into the body of the carb and is not replaceable.

It has now been 3 days since adding the Seafoam. Snowblower runs (still a little surging and popping) and the carb leaking is still a factor.

My question- is it more likely to be some kind of physical damage to the needle/seat or just a varnish/gummy deposit in the area? My guess is just deposits, but is it worth disassembling and trying to clean or just get the rebuild kit and replace the parts? Or should I just try running some "Mechanic in a Bottle" through, I understand it is the best for dissolving buildup.

Thanks!
 
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Old 01-15-19, 01:15 PM
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Even when drained some fuel remains in the carburetor so I suspect that the carb is gummed up a bit. As a quick first pass I would remove the carburetor bowl and clean the float valve needle tip and seat. Also remove the main jet and give it a cleaning. When you get the bowl off if it looks nice and clean that might be all you need. If the bottom of the bowl is yellowed and covered in varnish or sticky goo then you might need a more thorough cleaning.
 
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Old 01-16-19, 12:13 AM
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Best thing to remove fuel varnish? Paint thinner? Carburetor cleaner? Kerosene?
 
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Old 01-16-19, 06:02 AM
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I use carburetor cleaner or MEK.
 
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Old 01-17-19, 09:55 AM
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Took the carb apart last night, it was clean as a whistle. All the hoses were fine, the float needle was in great shape, the needle seat was pristine. The jet was perfect.

At a loss now, I did note the edge of the float bowl was not finished very well, but that's what the bowl gasket is for. I am planning on pulling the spark plug to see if it is clean and gapped correctly. That may have something to do with the popping noises, but still don't know why it's leaking gas.
 
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Old 01-17-19, 12:01 PM
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The leaking gas is most likely causing the popping too, it's running too rich because the float needle isn't shutting the gas off. This allows the fuel level to be too high in the bowl and it runs rich and leaks when not running. The fuel level in the bowl should never reach the top where you see a rough spot. If it has a brass float, take it off and shake it near your hear to hear if there is any gas in it. If not, time to replace the needle and if it has a replaceable seat, replace it too.
 
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