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Mowertech37, Small Engine Technician
Category: Small Engine
Satisfied Customers: 16
Experience:  Been in OPE since 1988 Currently have Website and helping others
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I have a craftsman snow blower with a tecumseh 5 hp snow king

Customer Question

I have a craftsman snow blower with a tecumseh 5 hp snow king engine that has a fuel problem that appears too be running too rich. It misses at high rpms and if you take the intake box/cover off and run it without it runs flawlesly. Have replace the original carb with a kit, and then a new carb, but it seems too be getting worse not better.
Submitted: 5 years ago.
Category: Small Engine
Expert:  Jon K. replied 5 years ago.

Thank you for choosing Just Answer, my name is XXXXX XXXXX I will do my best to help you find the answer you need to resolve your problem.

Does your carburetor have a screw type jet at the bottom of the float bowl? And did you replace this carb with an original Tecumseh carb or an after market one?

Customer: replied 5 years ago.
Yes it has the screw in jet at the bottom of the floatbowl that also holds the float bowl too the carb. It is a aftermarket replacement for the original 640084B carb. I put a kit in the original carb, but it too was acting the same way as the replacement.
Expert:  Jon K. replied 5 years ago.
If the replacement was an Oregon branded carb then you will need to change the air fuel mix settings. Start your mower and run it full speed. Reach under the carb and turn the screw out ( counter clock wise) Do this slowly. If the engine starts to run worse then begin turning it back. You should find a sweet spot with this screw that will smooth your engine out
Customer: replied 5 years ago.
brand of carb is ROTARYcorporation glennville georgia, adjustment screw is on the side of the carb, and its covered by a plastic plug. took out the plug and the screw is bottomed
Expert:  Jon K. replied 5 years ago.

The adjustment screw on the side of the carb should be bottomed out. If unscrewing it a little smooths the engine out then you will need to run a stiff wire through the hole at the end of it and try to open it up a hair.

The adjustment screw that I am talking about is on the very bottom of the carb in the center of the nut that holds the bowl on

Customer: replied 5 years ago.
There is nothing on the bottom of the bowl that can be adjusted, it is tightened up to seal it and there is a small spring loaded ball check in the center of the nut, but no adjuster.
Expert:  Jon K. replied 5 years ago.

Ok then lets take care of both jets. The nut in the bottom center is your main jet. Remove it (pinch off your gas) and then use a small wire to run through the tiny hole in it (see picture) While you are at it unscrew the jet on the side and run a wire through that as well. Try that and see if it has smoothed out?


Customer: replied 5 years ago.
both orifices are clean, and unplugged, choke butterfly however seems to be cocked a bit too the side when its fully open, and sitting at a slight angle. there is a visible difference between the old carb and the new one in this regard, its not fully open.
Expert:  Jon K. replied 5 years ago.

A very slight angle should not make a difference, if it is closed at all then it could cause this. It is strange that the carb runs better with the air box removed.

Does the engine run any better when you engage the auger, sometimes adding a load to it will use the excess fuel to smooth it out

Customer: replied 5 years ago.
If you shut off the fuel supply at the tank, just before it runs out of gas and stalls, the engine comes up to the high governor, and runs properly. It creates a leaner mixture just before it runs out of gas, which makes me think that its running too rich, and the black soot all over the inside of the air box leads me too believe its getting too much fuel. If I look into the venturi when its at max throttle, the fuel is coming out in the air stream in drops, and its not atomizing.
Expert:  Jon K. replied 5 years ago.

It does sound like a rich condition, which is opposite the normal settings on a new carb. Have you tried backing out the jet on the side yet to see if this leans out the mixture?

Also you may want to look at the float and make sure it is level. if it is you may want to bend the tab so that is a little lower then level

Customer: replied 5 years ago.
I will try the float level tomorrow, im tired of working on it today, dogone thing got me down, but never say die. thanks jon, i will get back too you when the daylight comes again.
Expert:  Jon K. replied 5 years ago.
Not a problem, I will be back on again tomorrow evening. Please also try the side jet to see if that helps
Customer: replied 5 years ago.
Have tried the side jet, but adjusting it gets backfires thru the muffler, and with it out a little, it runs good at idle but on the top end it runs laboured, and wont reach max rpm . I almost think that there is something wrong with the solid state ignition box, as it appears that the ignition timing is not advancing at higher rpms.
Expert:  Jon K. replied 5 years ago.

I doubt very much that it is the ignition. These ignition coils are timed with a key that holds the flywheel to the crank. These almost never shear on a snowblower but it may have and is worth checking. I still believe that your issue is within your carburetor. I am taking a look at a write up on your carburetor and think it is at least worth a shot at reading. I noticed that I sent you a picture of a B+S jet, the Tecumseh jet will have 2 small holes, the only other issue it may be in your carb would be the main nozzle that is up inside the carb.

Take a look through this site and pay attention to picture number 5 and 13

Customer: replied 5 years ago.
All of the holes are clean, although the one in the end of the restrictor plug was plugged, opened it up still will not rev too the limit, took the main nozzel tube out, and checked the hole, its clean.
Expert:  Jon K. replied 5 years ago.
Because it runs flawlessly with the air box cover off I am pretty sure we are in the right area looking at the carburetor. Do me a favor please and try running your snowblower with the fuel cap removed. I know it sounds odd, but if the cap is not venting correctly then it will not allow the carb to run correctly either
Customer: replied 5 years ago.
already tried that, does not change the result. vent is not plugged.
Expert:  Jon K. replied 5 years ago.
You have me stumped, I am going to release this question back to the pool of experts and see if someone else has another idea. Please do not respond to this answer as it will lock the question back to me. Good luck, sorry I was not able to help more
Expert:  Mowertech37 replied 5 years ago.
Just a quick question have you checked your air filter yet ?

cause if your engine is running rich a clogged air filter will cause it to run rich

Expert:  Mowertech37 replied 5 years ago.
Here is a list that you can check
1. Dirt or waste in carbureter or gasoline pipe, causing weak mixtures.
2. Stale gasoline.
3. Air intake partially obstructed, causing rich mixture.
4. Bad carbureter adjustment.
5. Trouble with float.
6. Choked muffler.
7. Lack of oil on piston, or too thin oil.
8. Leak through valve (generally the exhaust valve).
9. Leaky spark plug.
10. Valve timing wrong. This is most likely due to the fact that the cam-shaft, etc., have been taken out and replaced with the gears in incorrect angular relation. It may, however, be caused also by wear of the cams, push rods, or valve stems, by spring in the cam-shaft or valve lifters, or by the slipping of cams.
11. Broken or worn piston rings.
Customer: replied 5 years ago.
No air filter, its a snow blower. Compression is 100 psi, motor has approximately 25 hours on it, although its an old design side valve motor.
Expert:  Mowertech37 replied 5 years ago.
Have you checked the other areas on that list above ?
Customer: replied 5 years ago.
Ok, here it goes again. This unit has had one new carb, and the old one rebuilt too many times too admit, fuel and fuel system is clean and new, fuel cap is not plugged in the vent area.carb has no adjustments that can be set externally, float is good and not leaking gas internally. muffler is not blocked, and engine has never been apart so unless they changed themselves internally, temp here is currently sub zero, and its got 5w30 oil in it as per specs/synthetic oil is used. If the compression is 100 psi, valves not leaking, im stumped and ready to throw in the towel. unless the ignition-solid state is a problem Iv worn out all other avenues.
Expert:  Mowertech37 replied 5 years ago.
Issue is i never worked on a snow king since i am in a area that hardly ever gets snow im going to have to opt out and hope someone that has worked on these snow kings can answer .