Snowblower backfiring

[Mueller]

I have a 13 HP Ariens snowblower that started backfiring after about an hour of use. Before I bring it to the shop can any of you suggest what would cause it to backfire and allow me to fix it?

Thanks
Mueller

[Apple Guy]

Can you explain when and how it backfires.

[AllenW]

Running lean would be my first guess, and probably the easist to cure, dump a half cup of seafoam and new gas in it and run it.

A way to maybe check that is to add just a little choke and see if the back firing goes away.

Al

[Mueller]

When I start it up if I turn off the choke before the engine warms up it will back fire. I have to have it run for about 3 minutes before I turn the choke off. Last Tuesday I used the blower for about an hour and it backfired a couple of times when i finished the job it started backfiring like crazy...could it be water in the gas?

I had the same problem with my Ariens found out that when it got hot the plug wire at the plug would get lose. I squeezed it together a little to make it tighter on the plug and that solved it.

gdi

Try opening the main jet a little. Do this while it is running by opening the screw on the bottom of the carb bowl. An 1/8 to 1/4 turn is probably all it will need. Yo will hear the engine change "pitch" as you do this. Make her run as smooth as you can and you will have it right.

[2746]

Mueller, are you the one that was going to have knee surgery/replacement? If you did it must be going well if your out snowblowing!

[REW]

I agree,
A lean condition causes backfiring, that will likely be cured by opening the main jet a bit.

Just to be sure - it is also a good idea to change the spark plug.
You may have a plug that is partially fouled, and could be causing part of the problem.

However, normally, when you start backfiring, after running, it is caused by a lean run condition.

Take care
REW

[Mueller]

Yep had the surg on Halloween and next one on this coming Tuesday. Still some pain but I have good motion. The knee that is going to get done next is really starting to bite. did some snowblowing and had this problem and want to get it fixed before I go in.

[Apple Guy]

First drain the gas and get new non-ethanol based gas. This is premium gas at certain gas stations. There will be a sticker on the pump stating so. Buy some Sea-Foam and use 4 oz.per gallon. If you can't find that get stai-bil. Try running it now. As Rew said, check out the plug. Replace or just check it out for damage to it's porcelain.

If it is still doing it then look for a lose carburetor. You may have to pull the air box or snow shield sheet metal to get at it. A lot of times the main nuts that hold on the air box inside the air box are also the carb nuts too.

At this point I myself would just pull the carb and pull it apart and clean out all the jets and fuel passageways. Then see how it runs.

Then I would question if it could be a vacuum fuel pump depending how old your machine is.