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

Got a problem.  Pulled the trusty I think 43 year old Ariens snowblower (with it's second engine, a Tecumseh HSK70 with maybe 20 hours on it) out of it's covered outdoor storage space.  Wanted to look at the belt, grease it and lubricate what I knew earlier was a sticking shift bar (the shaft inside the case gets smeared every few years), so started it up to take it the the basement hatch.  It ran for a minute - just long enough to get there, then started running rough, then backfired through the muffler, and now I can't even start it.

Took apart the carb to check the flow and needle, found a clean fuel bowl but clayish colored fine particles in the gas.  Drained some through the inlet (float valve thing) and it was full of junk settling like an almost solid thin layer in the bottom of my container.  Then I'm thinking - didn't run it last year or drain it so the fuel was in there at least two years.   I can't remember the last time I filled the portable can so maybe the gas is three or maybe even four years old.  I probed the tiny hole in the needle adjuster and blew it dry.   And still couldn't start it, but it sputtered once. 

The idle mixture circuit has the most passage ways in the carb.
If you remove the mixture screw and spray some carb cleaner
in the hole it may help.  Be aware that there is a small brass washer
and an o ring that will likely stay in the hole when you remove the screw.
There are three very small holes in the sidewall of the the carb throat that are part of the idle mixture
circuit.  They are in line with the edge of the throttle butterfly on the outside wall.  They can get clogged. 
But you can't get to them without removing the carb.
The is also a passage on the bottom of the carb throat just behind the choke shaft.
It's easy to miss because the shaft and butterfly kind of hide it.
If the engine won't run without the choke on.  You probably have a restriction somewhere
that is going to require that you remove the carb.  and clean every passage with a wire.
Also check the carb bowl bolt.  There are the large holes that are easy to see.
But there is one very small hole between the two sets of threads.  Right where one set of threads starts
You have to look very closely to see it.  It's very easy to miss.  But it's there.

Here is a photo that might help.

Also look at the photos
"What's under the Welsch Plugs"
that I just posted.

The small washer and o ring in the one photo.
Would go on the Idle mixture screw.
Spring goes on the screw first, then the washer then the o-ring.
That whole assembly goes into the hole on the side of the carb.
Doesn't hurt to rub a very small amount of grease on the o-ring
before putting in on the screw.
The washer puts equal pressure on the o-ring and keeps the spring
from tearing it up.
The o-ring makes a tight seal around the screw shaft when it is compressed
between the spring tension on top and the bottom of the hole it's going into.

After saying all that.
There is also a rubber seal and washer on the bottom of the bowl nut.
If you removed the needle from the bottom of the bowl nut. 
You will see it.  You usually have to carefully pry it out of the nut.
Although sometimes it will come out by itself. That rubber seal, washer and spring
serve the same function as the one's on the Idle mixture screw.
They create a seal.
The o-ring and washer in the photo could be for the seal on the main jet needle.
Don't know.  Just make sure you have the seal set up on both needles.

No, nothing goes between those two parts.
Also be aware that the float bowl has to go on a certain way.
If you look at the bottom of the bowl you will see that it is not flat.
one side has a deeper depression.  You want to put the float bowl on
so that the deeper depression side of the bowl is away or on the other side
from where the hinge point is for the float.  You want the far side of the float to be able to
hang down into that deeper depression.  That is why it's there.

I hope this will help.
If you were to hold the carb just as it is in the photo.
Then take the bowl and put it on the carb as it's shown.
(and as I described in my last post)
Then lay the fibre washer on the bowl.
Then screw the bowl nut neddle assembly into the hole.
You would be done.
Nothing goes into, or between the copper tube that is in the carb body(called the Emulsion tube)
and the end of the Bowl nut main jet needle assembly that gets screwed onto the carb body.
To hold the float bowl on the carb.