Gas Leak 10515

mulligan

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So after cutting my grass this week with my 1994 10515 I shut the gas supply valve and allowed the mower to run out of gas as I always do. When I went in the garage the following morning there was a bad gas smell and quite a large puddle of gas under the mower. It's not leaking out the carb and down the deck it's definitely leaking under the mower deck and I see gas on the blade. I know the valve is shutting the gas supply from the tank to the carb and I know the tank doesn't leak. Anyone have any thoughts? Thanks Jeff
 

Lawnboy77

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If the valve is working properly then it almost has to be a leaky tank. If the valve is working properly and you close it and run the engine dry then there should be nothing to leak out other than maybe a very small residual amount in the bottom of the bowl. Any substantial leak after that would almost have to come from the tank. It's not uncommon for those particular tanks to develop a leak, either at the seam, or from a crack at the outlet nipple. My bet is either on a bad valve, or a leaky tank.
 

lewb

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Is it leaking out of the exhaust tube (for lack of knowing what it is) underneath? Of course I am assuming this is a 6.5 duraforce, Gas running through the needle, float out of adjustment or needle not seating.
 

Lawnboy77

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A 10515 is not a Duraforce, it's a self-propelled F series. I think you could be right though in that the needle and seat are not functioning properly, but for this to happen I think there would have to also be a failure of the tank shut off valve to get fuel coming out of exhaust. Even with a leaky needle and seat if he turns the valve off and runs it dry then the needle and seat become a non-factor. It's very common on some mowers and that's why folks install the shut off valve, if it's not included, but as far as I know all the F series mowers have a tank shut off valve.
 

mulligan

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Thanks for the replies.
If the shut off valve is not working properly, when I close it wouldn't the mower continue to run instead of shutting down after a couple minutes? What if I try this after cutting this week? Close the valve and allow the mower to shut down then disconnect the fuel line from the tank and see if I get any leakage. I could even remove the tank altogether if you think that's a good approach. Thanks
 

Lawnboy77

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Sounds like a good plan to check the valve for leakage. I think I would also replace the carb needle and seat. The valve could restrict fuel enough that the engine fails to run when closed, but over a day or two could still leak enough to flood the engine if the needle and seat aren't functioning properly.

Edit: I looked up that valve and Partstree is showing it at around 30 bucks for the kit. It maybe a better option to just replace the needle and seat in the carb and live with a slight leak at the tank valve (If the leak is NOT an external leak). If you have the original carb I think it should be a metal Walbro and those needle and seats are very reliable, as a matter of fact I have never had one of those to leak out on the ground and I'm pretty bad about not closing the tank valve sometimes. Those carb kits for the Walbros are very cheap on ebay. Below is a link to one of those (the kit part number is K11-LMR) The welch plugs in those kits will not be needed for an overhaul. Just wondering if maybe the last time you cleaned the carb you accidentally blew compressed air through inlet port and lost the seat. Yep that happened to me this summer, just be careful when you blow it out with the seat installed.
http://www.ebay.com/itm/Carburetor-...581428&hash=item1eac46550b:g:uyQAAOxydlFS01Sf
 
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mulligan

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Thanks for all the info Lawnboy 77. I've never done anything to the carb on this mower but I think it may be plastic but I'll check. Are the needle and seat difficult to change? I've owned this mower since new in 1994 and I've replaced a number of parts including the ign coil a couple times, several parts inside the rear wheel drive assembly, both upper and lower seals, primer bulb 3 or 4 times and more but I've never touched the carb as it's always run well. I've always taken care of it even run the gas out and store it in the basement in winter. Pretty much stripped it one winter and repainted it. Yes wife makes fun of me. But back to my current issue, Yesterday I started it and let it run for 15 minutes or so before shutting the fuel valve and allowing it to run out of gas and this time I have no leak at all. Could it have been just a fluke?
 

Lawnboy77

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That's great news! Sounds like a fluke to me. I like the way you keep care of that machine. You have a primer so yes you are probably right in that your carb is the plastic version, not the Walbro. I was going off the parts catalogue and it showed the 1994 model 10515 with the metal Walbro with the choke only, and the 1995 model with the carb you described with the primer bulb. No biggie, it's probably just a mistake with the catalogue. If you ever need to change the needle and seat it's really easy on either carb, with the Walbro removing the seat is easy, just a shot of compressed air in the inlet and it goes shooting across the garage. Just don't do that with the new seat installed or you'll end up scouring the floor for the next 30 minutes trying to find it. LOL
 
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mulligan

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Well here's an update. I cut the grass yesterday and when done I shut the fuel valve and allowed the mower to run out of gas. Gave it a good cleaning before putting it away and there's no leak so let's hope it was a one time thing. If it happens again I'll let you know but thanks for the help.
 
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