Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

OK. I'm so stumped on this I've scratched myself bald. I have a Bolens snowthrower with a 10hp tecumseh. This fall I took it out and turned on the fuel valve and it leaked profusely. Upon removing the bowl I found what I expected, a float filled with gas.It had a small and detecable hole in it. Fine, I replaced the float, needle and seat. Yes the seat is in correctly,( ringed end up into the carbs inlet shaft). The open end of the retaining spring is facing the inlet side of the carb.The float is set with a 11/64 drill. No gummed debris in this shaft. Everything is spotless. No housing cracks. But when I install the carb back onto the engine it continues to leak, A lot. I removed the carb and turned it upside down and blew into the fuel inlet. It sealed the air fine. reinstalled and it leaked. I did this several times even taking it apart to reinspect it. Next I injected water into the bowl and it stopped the flow as it should have. Even with ample pressure it would not leak. Cleaned and dried the carb and reinstalled it. I continues to leak gas. I Dumped the bowl of gas, reinstalled it, and without removing the card I injected water as it sat undisturbed on the engine. It wouldn't leak. No mater how much I tried. Great, I removed the water and let the gas flow again. Yup ! it leaked. I'm done. That's it.Six hours later and no more hair. Now I wait until I can get this thing exorcised or someone has an answer. I've rebuilt many engines and carbs but this ones got me.
Hope someone can help. Before the next big storm! Thanks. Raymond

Given all of the symptoms. I.E. works properly with water not with gas. Its got to be a problem with the float adjustment and the slightly denser water is causing the float to rise a bit higher  to seat properly.

Since it works with water the needle valve/set are fine, the viscosity difference between water and gas won't make a big enough difference to affect the the valave directly, just the float.

Since you have tried multiple floats its not a damaged float issue.

Since you have done the "drill bit adjustment" there are two possible solutions:

1. Try using the next smaller drill size and see if there is a difference. If there is try progressively smaller sizes till it works;
2. There is a tab on the float that the valve stem sits on, try bending it a bit so the valve stem is pushed more firmly into the seat.

Either method effectively does the same thing, it causes the valve to close a bit sooner and therefore a bit more completely when gas is uses.

i had the leak you are describing on a koehler lawn tractor engine. you would turn the gas on or leave it on and it would leak out the intake.the float level was too high and the excess gas would run out the intake.it was probably designed like that so if the float stuck it would not pour raw gas into the cylinder. i would double check the needle and seat or replace it with a vinton tipped needle and seat and set the float level down a good 1/8" or at least what you feel is enough to eliminate a high float leak. when you take the bowl off try to catch all the gas that comes out in a container,once the bowl is off  put your finger over the bowl screw hole and pour the gas back into the bowl and see how much it fills up.if you have a needle and seat issue the bowl will be full to the top and then some thus running out the next available outlet,the intake .you should have a level of gas much lower than the top edge of the bowl because the float  when assembled will displace  gas and raise the level even higher . it's either the needle and seat is leaking or the float level is too high.

Raymond,

I didn’t know you were using a new float that came in a kit that’s supposed to be for your machine. First thing I would do would be to try it with the old float. If that stops the leak then the proplem is the "one size fits all" float and needle valve kit that doesn’t work quite right in your specific application. I would use the old float, but if you can’t then change the adjustment on the new float so that it doesn’t leak and the engine runs ok. You may have to play with it a bit to find the right setting. Once you do, write it down because you’ll likely have the same problem with anything you put one of these kits into.

Mac

  I don't have the original float as it had a hole in it and was flooded with fuel. But I did match it up with the new floats as well as the needle and seat. I thought there might have been some side play to cause it to hang but no where enough to bind against the bowl or center casting. Although the needles are the same diameter I did notice a lot of sloppy play that might cause it to bind but in my attemps to cause it it wouldn't

Raymond

Raymond,

It’s nearly impossible to tell if a float is the correct replacement just by looking at it. How high it floats depends on both it’s weight and it's displacement, and with any complex shape, you can't tell just by looking at it. There are ways of measuring the displacement, but there may be an easier solution. You said you had three other machines that you purchased the same carb kit for. If that's accurate then take the float out of one of those other machines and give it a try in your snow thrower's carb. If it works you'll know that the float you got in the kit is incorrect. If one of the other machines is not used in the winter you could cannibalize one of them to get your snow thrower working. That will give you time to figure out why the kit doesn't work for your snow thrower carb and maybe find a proper replacement.

Mac

Thats the plan for tonight Mac. Remove the float and needle from the tiller and swap them out.

    I did a glass test with the float to see how far and at what level the float would have to rise before the seal was active and it ( the gas)was pretty much level with the top of the float at that point. I did that with one of them, Not both. Still baffled as to why it won't float in the bowl but I know its going to be a real simple, in my face solution.

Raymond

raymond! let us all know what you learned when you have the solution. mkd

tolltech wrote:

This one just went past me.Can someone explain what this is all about. What it does and how to use this technique.

tolltech,

l've ran into this problem many times l would bet money on it, that the fuel line going from the gas tank to the carb is starting to fall apart inside the hose and little pieces of rubber are getting stuck under the needle, on tecumseh 10 hp the fuel line runs between the fan shroud and block which cause it to get hot and the rubber hose to fall apart over time. if u take carb bowl off when it leaks and look inside and u will probally see there's dirt (little rubber pieces) in the bottom of the bowl. u can also add a inline universal fuel filter when u replace the line highly recommended, they have a fuel filter in the tank but it sometimes it gets clogged and people poke at them and break the filter open, then if your tank is at  all dirty it goes right into the carb. that would why when u feed it with water it does'nt leak , but as soon as u hook the fuel line up it leaks right away.

good luck

niper

 Niper

        Sounds like good advice. I've seen before much of the same, even where snow throwers that sit for long periods accumulate sediment in the line then cause this scenario but when I acquired this I HAD TO replaced the line as it leaked fuel half way through the first winter( 06) and ignited into a rather frightening scenario. This engine is an 1983 model. So the line is new and at the time I also removed and cleaned out the tank. I have not since my last notation been able to work on it so I will report my results then. Supposed to snow tomorrow so tonight will be a do or die retry.

Raymond