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

I have an old Ariens ST504 snowthrower that has served me well for many years. It has worked well even already this season Have always drained gas after the season is over, run till quit, greased, etc... so it's always been well-taken care of. It's a 5 horse...and I believe it's a Tecumseh. Looks like it was manufactured in 1978 or 1979. My problem currently is with the carb I have just thoroughly cleaned -- because the engine was trying to die when under load. So cleaning was in order. I've always had to run the machine with the choke switch on full. Anything less...even at 3/4's choke would cause the engine to start sputtering. I'm currently desperate because I live in Syracuse and after 2 days and 24+ inches of snow...and more on the way... I know no repair center will fix this quickly as they're likely up to their ears in similar requests... so I'm on my own. Obviously my careful(?) preventative maintenance did not keep me out of trouble. My question is -- After cleaning this older carb thoroughly and putting it back together the issue I now have.... and didn't before I disassembled and cleaned ....is that when I reopen the petcock under the fuel tank and gas flows back into the carb...in a matter of seconds (5-10) I then get a very small stream of gas shooting out, what I presume is a very tiny "venting hole". It's near the top and on one side of the carb. Hole is about the size of a small needle hole. Somehow after cleaning, this issue has developed. Obviously I can't even "try" to start my machine with this condition. I did a search on this forum and noticed in 2009 someone posted the exact question I have. It was at the tail end of comments about a similar Ariens carb problem. He too noted fuel squirting out a very small hole near the top of the carb assembly. Unfortunately no one responded to his question... so I'm lost. Any advice? Suggestions? thanks. Jack F

Additional Note ... I notice now that when I push the rubber primer bulb before starting the engine that the gas will squirt out the tiny hole. If the bulb is pushed 3-4 times as if priming prior to start, the fuel squirts out. I can start the engine and it seems to run fine now...with the exception of the dangerous gasoline stream (*though very small) right next to the exhaust. JF

If you have to run the engine with full choke, the carb is NOT clean.  Your main jet is probably plugged.  A carb has to be taken completely apart to be cleaned.  Every jet, orifice and gallery has to be known to be clean.   Get yourself some thin multi strand copper wire and take one strand off to clear holes, galleries and jets.  Spray WD-40 through them after the wire treatment then blow everything out with compressed air.  Once that is done, the engine should run without the choke.  The gas leaking from the carb sound like the float needle isn't seating properly.  Could be caused by a couple of things.  Your float might have fuel in it, if it's a hollow type or it may be mis-adjusted.  It could also be that the float needle is contaminated/worn or the float needle valve seat is contaminated/worn.   Carburetors are sensitive instruments and do not require much to put them out of commission.   

Thanks..Borat and Daniel...will take your advice and take a look at these... I did notice when I removed the needle from the base of the carb...the small rubber gasket seems to show some signs of deterioration. This rubber gasket seems to be about the diameter of an eraser on a pencil. it's mounted just above the spring that surrounds the needle. Wonder if this is a part that can be found...if necessary. Hmmm. Will disassemble that carb again and soak everything overnight. Keeping my fingers crossed. The float seems to be okay..doesn't have any fuel inside but would probably be a good part to replace after 30 years. If that float has a little piece attached that seals off that vent(?) hole I can see where this might be a good thing to inspect ;-) JF

The float acts on a lever.  One side has the float, the other side of the fulcrum (pin) is a piece of flat brass that the float needle rests on.  Sometimes there is a very small wire clip that holds the float needle onto the brass plate so that it follows the movement caused by the float responding to fuel level.   Maybe someone here has an exploded view diagram of your carb that they can post.  It will help you understand where everything is and how it all works.  The small gasket on the bottom of the carb is a seal to keep fuel from dripping from the adjustment needle on the bottom of the float bowl.  If it's not leaking, don't sweat it.  

Here are your diagrams:
http://outdoorpowerinfo.com/repairs/tecumseh_carb_632334a.asp

Make sure the bowl has the step lined up with the float pin.
If you want to test the needle and seat you can hold the float up and blow in the gas line.
To test the float you have to pull it off and shake it next to your ear and listen for anything inside it.
If you hold the carb upside down, the distance between the far side of the float and the seat where the bowl goes should be 11/64" and can be tested with a drill bit.

My thanks to all of you. As a novice who'll attempt almost anything (and always have parts left over) you've put me on a course to repair success...I hope. After the mention of the needle attached to the float...I suddenly thought.."Hey, something's missing here." That part had fallen off, probably when I removed the cup on the bottom of the carb. I found it on the floor after looking around for that tiny part So sure enough...that's likely why the gas was coming out of the small hole... nothing to seal it off. I've taken your advice and removed the carb...then detached the float and set aside...then put the whole assembly in a small can I filled enough with carb cleaner to cover all the necessary areas. Surprise of surprises...didn't take long for the cleaner to start looking a little nasty. Will soak it overnight and give it a good shot of compressed air in the morning and hopefully I'll be able to come back here tomorrow and say it purrs like a kitten and no more squirting gasoline.... either that or you'll hear a story about a Syracuse man who's snowblower exploded and wiped out half the neighborhood. Thanks again... JF

Wow, that is amazing that it was the same exact problem that the Uncle had (also in Upstate NY) the same week, losing the float pin on the floor!  Too funny.  Good luck with turning off the choke next.  I'll have to be learning all this stuff soon, snowblower is brand spanking new for the moment, but I need to learn how to take care of it.

-dan

Don't forget the copper wire in every hole you find.  Also, some holes in the venturi (carburetor throat) are so small they're barely visible.  They are usually the slow speed orifice.  Look closely into the venturi to see if there's a small hole that needs cleaning.  The diagram should also help you find the fuel circuits.   If you clean the carb properly, the float level is properly adjusted and the float needle seals as it should, the carb should work fine.  Be very gentle when working with the float and float assembly.  If it's correctly adjusted, it should go right back in and work fine.  In order to prevent future carb problems, it would be wise to install a small  in line fuel filter. 

Hey Borat -

Sounds like you work on quite a OPE equipment ....
By chance, own or use a ultrasonic cleaner ?

I've been looking at a couple made by Crest.
If you know of any other brands I should be looking at, wouldn't mind some recommendations...

chefwong wrote:
I do a lot of small motor work but I can't help you with your request. 

My hobby is rebuilding/restoring/performance enhancing old two cycle Yamaha motorcycles.  I do plenty of engine/carb work and I don't rely on anything but very thin wire, WD-40 and compressed air. No sonic devices and no more miracle cure additives. 

 I own eighteen pieces of OPE, 7 motorcycles, 2  ATVs, 1 snowmobile and 3 outboard motors.   All of which I maintain myself.  I also fix friends and neighbours OPE. 

Carburetors are easy to work on provided it's not a plastic model that cannot be disassembled.   Personally, I don't subscribe to anything but the simple methods I've already mentioned.  There's no easy way to clean a carb and be sure it's done right.  It has to come apart and every fuel passage confirmed cleaned.  If you want to save yourself a world of grief, save the money you'd be spending on an ultrasonic cleaner and buy some in line fuel filters.  Best bang for the buck for any fuel system.