snowblower carb issues

[Millwright]

Snow blower number is 536.918200 for sure. Engine number is nearly illegible.....143.696082, or 143.696682, or feel free to guess! SER is 8263B.

I am working on a craftsman snowblower, an older model 5hp / 22"path. It has sat for 3 years at least, and I am trying to clean the carburetor enough to see if its worth fixing. I've actually got it running for a few seconds, longer if you leave the choke on, and as long as you care to mist axillary fuel in it will stay running. Obviously running out of fuel. Fuel line is new, tank is clean, and free flowing at carburetor inlet.

Here is my specific question....if you view the carburetor from the bottom, the casting has the main jet in the bottom. I have cleaned it thoroughly. Next to where the jet screws in, there is another passage running vertically next to the main jet well, It has a tiny hole in the side maybe a 1/2" up from the bottom, and the main hole in the bottom next to the hole the needle jet screws into. Both holes, meaning the small hole in the side, and the bottom hole that would be below the fuel level, appear to be plugged on purpose. That, or they are just really well plugged from sitting. I've soaked this carburetor overnight in good cleaner, used compressed air, etc......I really just don't know if they are plugged on purpose or not. So before I do anything else, I need to find out. HELP!!!

[bgsengine]

Snow blower number is 536.918200 for sure. Engine number is nearly illegible.....143.696082, or 143.696682, or feel free to guess! SER is 8263B.

I am working on a craftsman snowblower, an older model 5hp / 22"path. It has sat for 3 years at least, and I am trying to clean the carburetor enough to see if its worth fixing. I've actually got it running for a few seconds, longer if you leave the choke on, and as long as you care to mist axillary fuel in it will stay running. Obviously running out of fuel. Fuel line is new, tank is clean, and free flowing at carburetor inlet.

Here is my specific question....if you view the carburetor from the bottom, the casting has the main jet in the bottom. I have cleaned it thoroughly. Next to where the jet screws in, there is another passage running vertically next to the main jet well, It has a tiny hole in the side maybe a 1/2" up from the bottom, and the main hole in the bottom next to the hole the needle jet screws into. Both holes, meaning the small hole in the side, and the bottom hole that would be below the fuel level, appear to be plugged on purpose. That, or they are just really well plugged from sitting. I've soaked this carburetor overnight in good cleaner, used compressed air, etc......I really just don't know if they are plugged on purpose or not. So before I do anything else, I need to find out. HELP!!!

They are plugged with small round steel "BB" or "Shot" - that is the fuel feed for idle circuit. Idle fuel is fed from in the main jet area (if you look closely at the main high speed mixture needle and body, you'll notice a tiny cross-drilled hole and.or a groove cut in the middle of the brass threads)

The tiny jets in the main nozzle need to be clear.

Also when you pull out the low speed mixture (idle mixture) adjustment screw, use care to note what type of needle end it has - If it has a long, straight unthreaded shaft that comes down and tapers quckly to a rounded tip, that'll be your idle AIR adjustment , and in that case, with float and everything removed, needles removed, and holding throttle and choke shafts, if you shake the carb, you should hear a rattle (That's the metering rod hidden behind those "plugs" you mention) and it should be loose and rattle around freely - Also note you must be very careful when putting the idle mixture screw back in to hold the carburetor in "NORMAL" operating position (Float and BOWL pointing DOWN towards the ground) - if you don't the metering rod can fall up in there and the tip of the adjustment screw contacts it and bends it, (also mashes the tip of the screw) , in which case you then need a new carburetor.

If the idle mixture adjustment has a longer taper and comes to a much sharper point (and taper starts almost immediately after the threads) , that is an idle FUEL mixture adjustment (And the carburetor will NOT rattle when shaken)

In either case, the idle circuit passages must be clear, and if you do not have an ultrasonic cleaner, hold the throttle plate wide open and spray carburetor cleaner (with the extension tip inserted into the idle mixture screw passage) and you should be able to see cleaner spraying out ALL of the holes (There'll be 3 or 4 tiny holes in the carb, with throttle plate closed, only 1 or 2 will be visible) - they are, in order, from the ENGINE side of the carburetor, the Idle fuel port, and the (2 or 3) Idle TRANSITION ports - If the first one is open, and the others plugged it may idle fine, and may run at full throttle under load fine, but will not accelerate smoothly (if not stall out when opening throttle) - if those transition ports are partially plugged it can also be the cause of "hunting" or "surging" - as the throttle opens, more to get more fuel, fuel starts feeding from the high speed nozzle (in the middle of carb) until it gets to where governor slows engine down, and as throttle closes no fuel is being fed through main nozzle any more, resulting in engine going lean again and opening up the throttle again. So, a lean surge at high speed (but not under load) can be caused by the idle transition ports being plugged, even if the idle port itself is open... so it might idle fine, and might run great under load, and surge at top no load or any speed but idle.

Bleh - I should do up one of those articles.. (actually plan on it if I can find the time!)

[Millwright]

my idle screw is tapered, thankfully, or I would have messed it up! good information all around. I'm going to soak this some more and see what happens. I will also look very closely at what you describe. thank you for the response. I'll let you know.

[Millwright]

UPDATE:

Gave the carb a good soaking, carefully checked the ports, reassembled and we are all good now! I did get lucky on the idle mixture screw installation. Mine does have a metering rod, I can here it moving freely, and I did not seat the screw hard enough to do any damage, apparently. Also, I may have had it in the upright position the first time I put it together, but that would be purely by coincidence! But, all seems well! Knowledge gained! Thanks.