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Discussion Starter #1
not a blower but I'll ask ... I just got (for free) a small Coleman generator, with a Tecumseh 5hp motor. It was the usual won't start, sat for years, machine. I cleaned out all the fuel system, cleaned out the weird Vector carburetor, changed oil and spark plug, and replaced a leaky oil fill tube. As I was setting the rpms, I noticed that gas was slowly leaking from the gas tank cap area. It seems to be vibrating/splashing up when running (the gas tank was only partially full), and slowly leaking around the cap. I could not find any cracks in the cap or tank, though it was hard to tell with the gas leaking. I tried another cap (from another machine) that seemed to fit and it leaked a bit too. Has anyone seen this before? I need a way to get a light source in the tank to look for a leak around the cap area. Otherwise I guess I'll take the tank off and see what I can find.
 

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Perhaps there is a gasket or an o-ring missing that sits in the bottom of the cap. You could add one that would help the cap seal.
 

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Is that a nick or crack in the rim of the filler neck I see in the second photo? If so, it might have damaged the O ring that is probably on the cap. Also, check to see if the cap is vented, and that the vent is not blocked. Might be easiest to find a new tank and cap.

Is there a lot of fuel splash if you run the thing with the cap off for a few seconds? Is it possible you are overfilling the tank?
 

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looks to me that the foam "baffle" on the cap has shrunk. did the other cap have the foam on it , and did it fit the filler neck somewhat snugly ?
 

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Discussion Starter #6
thanks all. I have tried 2 new caps (one with a foam baffle and one without) and one other old cap, all exhibit the same leaking. The foam on the original is in pretty good shape, and fits fairly snug in the tank. And there has been only a few oz of gas in the tank at the time (which may actually splash worse). I'm leaning towards a small crack in the tank, will work some more this weekend.
 

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I would pull the tank and drain out the gas, then submerge it in a bucket of water while applying 5 to 10 psi air pressure through the fuel line with the cap on, looking where the air bubbles are coming from.
 

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Discussion Starter #8
yeah Grunt, it may come to that.
 

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I would pull the tank and drain out the gas, then submerge it in a bucket of water while applying 5 to 10 psi air pressure through the fuel line with the cap on, looking where the air bubbles are coming from.
You will definitely get bubbles from the vent in the cap. The vent needs to be there to avoid a vacuum and starvation of fuel to the carb.
 

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The vent needs to be there to avoid a vacuum and starvation of fuel to the carb.
The vent usually like a duck bill should allow air into the tank breaking any sort of vacuum, but close to prevent gas and vapors from escaping.
 
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