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

Most likely you have a blocked atmospheric vent if the vent is blocked it would account for your symptoms. On the under side of the carb above the float is a welch plug. If you spray carb cleaner through the primer nipple it should spray out of the slot at the welch plug. There is a vent hole in the side of the carb here is a picture of a typical Tecumesh carb:

This hole must be cleaned out too spraying into that hole it should come out at the welch plug & the primer nipple or spraying into the primer nipple it should spray out the vent hole..

You didn't say where the fuel is leaking out of the carb.  I had a carb on a 6 h.p. Mitsubishi pressure washer that leaked.  Went through a similar process but not nearly as long as yours.  I found that the rubber gasket that sealed the float bowl had a twist in it.  Put the gasket in right and it hasn't leaked since.     

The Carb leaks ( pours ) out through the intake. I checked the atmospheric vent mentioned and I don't seem to find it although I have seen this on other cards, this one seems to lack one. I did blow out the body with high pressure air to make sure. I just returned the carb in place and it still leaked. I thought maybe the curse may have lifted but it remains.
I'm still confused though, if any of the vents were plugged, the level of fuel would slow and the either stop by equalized pressure or fill till the float lifted stopping the flow through the needle valve. Since there is only one way in for fuel which I did confirm it is still an issue as to why the float won't float !!
Raymond

Water is denser than gas, so the float would float higher in water then in gas. With water the float is floating high enough to close the needle valve. Either the adjustment is off somehow or the float is damaged in some way. No doubt you have shaken the float to check for gas or water inside the float. A brass float can easily be partially crushed if you use compressed air or a power washer to clean off the machine and you just happened to hit that atmospheric vent on the carb. A plastic float can be damaged by heat, such as during storage in the summer, or if it’s an old machine, by alcohol in the gas.

I would give the float a good inspection looking for any sign of damage such as it has become asymmetrical. If nothing is obvious, see if it even floats in gas. If you can get a new float that might be the easy way to eliminate it as a problem.

A frustrating experience indeed.

Sure sounds like your needle valve isn't closing completely, for some reason.
Maybe the water is just thicker enough that it can't squeeze by but the gas can.

Paul

Have to agree that it's probably a float/float needle  issue.  Is the float needle solid metal or does it have a neoprene tip on it?  Have you looked at the float needle & float needle seat with a magnifying glass for imperfections?  Another thing to look for is hair line cracks in the carb body?   Can you post some pics of the float bowl and  internal components? 

Glad to see all the responses and might add, surprised to see them so quickly. Thanks to all who have responded. Anyway, When I purchased the float and needle/seat kit I bought two as I have three other machines with the same kits.(Just in case). I tried both sets. Both needles do not contain the neoprene tips. I have those as well but they do not fit.
From an earlier mention regarding the atmospheric vent, on closer inspection I did find it and it was gummed up, probably from my excessive handling. I cleaned it out but that didn't work either. I reinstalled the carb and at first it looked like it worked but upon pressing the primer bulb it began its grueling flow out the intake.
I'm calling it a night and a few other things as well. Tomorrow is another day.

Thanks again

Raymond

 Does it only leak when you press the primer?
Packo

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.