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

I just got a used snow thrower. I had it started once and it loped while starting,. otherwise it doesnt start. it gets spark., i replaced the plug anyhow and check the boot end.. what happens is its seems to leak gas into the carb and engine from the gas tank. i dont know where its suppose to hold it unless i start it. . im not sure if its the gas tank or its suppose to drain down into the carb adn stay there until you try to start it. it just drains into the engine.. and eventually out of the exhaust. when i pull it . the presure of the cylinder just throws it out the exhaust. i did last night try to start, then it caught all the leaked gas into flames. so I think it would work fine. if i can keep the gas from draining into the engine until ready to be used.. im not sure where this is at? any ideas, help, what to look at. woul dbe greatly appreciated. especially since we are expecting snow today  EEK

caught all the leaked gas into flames.<BR><BR>

Wow, sounds like you've got a live one. There are different types of carb and tank feed arrangements. If you give the model and serial number off your machine it would help ID what you've got.<BR><BR>

Common types of carbs are bowl with a float and diaphram. <BR><BR>

The bowl and float type work by gas gravity feeding into the carb to the bowl. The flow into the carb is usually started from a flow no-flow lever in the gas line just under the tank. Once turned on the flow heads to the carb but may or may not enter the carb.<BR><BR>


Gas from the tank into the line enters the carb via a a hole that has a needle in it comming up from under the hole (this hole is where the line from the tank is attached). The needle just fits into the carb hole so can block gas when it is in the hole. The needle will let gas flow into the carb if the needle is lowered. It's stopped when the needle is up.<BR><BR>

The needle is controled by a round doughnut shapped device that has air in it and can float on gas. The float is inside a bowl at the bottom of the carb. Attached to the bowl is a needle that rides up into the hole made for it. When the needle is up it seals off the top of the hole so no gas can flow from the tank line into the carb from the line to the tank. <BR><BR>

When it's down it allows gas to enter the carb down into the bowl. <BR><BR>

When gas enters the carb and goes to the bowl it raises the level of the float inside the bowl. When gas gets in the flow raises float and the the needle attached to it enough to close off the top hole.<BR><BR>

If this all works the level of the gas is such that none flows out of the various holes in carb. When you use the engine the flot lowers and lets in a bit more gas to keep the level somewhat constant. <BR><BR>

If the float has a hole it will not float becase it will have gas in it.<BR>
If the needle is not attached to the bowl gas will continually flow into the bowl and overflow.<BR>
If the rubber seat at the top of the needle hole is damaged the seal is not good and gas can overflow.<BR> If the needle top is damaged it won't seal the hole.<BR>
There could be dirt stuck in the needle area to prevent a seal of the needle.<BR> <BR>

Depending on your machine you could remove any covers and expose the carb so you can get at the bowl. There usually a nut at the bottom you can unscrew to get access to view the float and needle. You might want to google around and look for a few pictures of these parts to help you know what you're looking at.<BR><BR>

Checking on the float and needle is not so difficult. You might have to take off the bowl and remove the float and needle to check these parts. You can shake the float to see if it's got gas in it. Clean up the bowl and needle area. Check the look of the taper on the needle. There's a very small rubber doghnut that fits up into the needle hole what might need replacing. You get one with a needle kit which is a few bucks.<BR><BR>

Getting a bit more familiar with the parts by getting info from some net searches or a book at the library could be helpful.

Foxy-

Don't try to start it again until you address the problem which is definitely the carb. You will also need to do an oil change before running the engine as from your description gas has definitely contaminated the crank case oil. Please list the Brand of the machine and the engine manufacturer which is probably on the engine somewhere. It would be most helpful if you looked on the starter shroud(the metal cover that encloses the starter pull mechanism) and post the #'s stamped into it. Those #'s will tell us a great deal about the engine . If there is a fuel shut off between the tank and the engine shut it off so that no more fuel leaks into the engine.

Marc