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Discussion Starter #1
I'm working on a murray with a Techumseh HSSK50 which had been stored outside in the weather for years. I replaced the rusted out carb and it will run if i use the electric starter and hold it for about 20 seconds then it will run and sound good for about 5-10 seconds before it fades out and dies. I replaced the coil and spark plug as well and it still does the same thing. One time i got it to run for 5 minutes and i took it up and down the driveway. I shut it off and it would not start again without the electric starter and it would die again after a few seconds. I'm wondering if it could be the valves? I've never opened one of these up and I'm out of ideas. Any assistance is appreciated.
 

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before going too much farther have you checked/clean the fuel system. possibly replaced the main supply line. i know sometimes the fuel lines collapse or clog with age.
 

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Discussion Starter #3
before going too much farther have you checked/clean the fuel system. possibly replaced the main supply line. i know sometimes the fuel lines collapse or clog with age.
Yea, the fuel line flows very well and is in good shape. I've popped it off the carb a couple of times and it will flow out nicely. I'm going to replace the primer line next but i doubt that will have much of an effect.
 

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if it has points and a condenser you might want to check them
 

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low compression would cause a hard-start issue; Valve lash &/or head gasket are the usual culprits... less frequently it's the cylinder walls / piston rings.

Do you feel much resistance when you slowly pull it over?
 

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The carb was replaced with what, exactly? Offshore parts can have QC issues . . . . might have gotten a bad or misaadjusted one . . . and not sure how the old one could 'rust out' considering that they are not steel or iron based . . . Did you consider cleaning the old one, or even open it and look? Might be an option, at least to test . . .
 

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Discussion Starter #8
low compression would cause a hard-start issue; Valve lash &/or head gasket are the usual culprits... less frequently it's the cylinder walls / piston rings.

Do you feel much resistance when you slowly pull it over?
The resistance feels about the same as any other similar sized snow blower, not unusually hard to pull.
 

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Tecumseh motors are so temperamental, especially the carburetors..If rebuilding the carburetor wont work, best bet is to replace the carb with an OEM carb, but check the valves and cylinder first before you invest in the carburetor..
 

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Highly don't think the carb would be doing that, OEM carb will cost a fortune and the chinese carbs are pretty good, I have yet to get a bad one and I have used them a LOT. With the compression, These engines have a compression release for starting so until it fires and the rpm starts coming up they ALL have lower compression. Go to a auto zone or the likes they have tools they let you use and get a compression tester and use the electric start to test it to get the rpm high enough to stop the compression release. If it has low compression then that will tell you and odds are it is a valve or head gasket.
 

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i am wondering about compression and/or vacuum leaks also. if it runs and then stalls, would this mean a possible fuel delivery problem? if it ran for 5 minutes and then would not restart would this point to a possible flooding condition? do you smell gas? did you pull plug and was it wet?

one time i had a similar problem and found out when of the carb mounting nuts was loose but if you just put on a new carb did you change the gaskets or just use the old ones?

when it's running can you spray carb cleaner around gaskets and see if the rpms go up?

i'm not a pro , just making suggestions on what i have learned here and done myself to find the problem.
 

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For that matter, does this engine have the small intermediate intake manifold like the HSK's? If so, then the carb bolts to it, and then it to the engine, and simply putting a carb on does not ensure that all is secure - different bolts into the block . . .
 

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Discussion Starter #14
here is a video of it running. it will start if it has been sitting for a while then quickly die. then i cant start it with the pull cord. If i use the electric starter it will do the same kind of thing. The video is with the old carb cleaned out and put back on. It does this with the new carb too. It is not a carb issue. Makes no sense to me that it would start and then die and refuse to start again. the vid:

Attached are pics of the new and old carb and the old coil that i changed. I'm going to pull the head off and check the valves next. I have a new head gasket
 

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That seems like a fuel delivery issue, Not the carb but it will run until the bowl is emptied then die, Won't restart right away until the bowl refills, Might have some gunk blocking the fuel line and it flows slower than needed, Fuel line is cheap and to swap it out on a Tecumseh use something to connect it to the old fuel line because it's a PITA to put in otherwise.
 

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Discussion Starter #16
That seems like a fuel delivery issue, Not the carb but it will run until the bowl is emptied then die, Won't restart right away until the bowl refills, Might have some gunk blocking the fuel line and it flows slower than needed, Fuel line is cheap and to swap it out on a Tecumseh use something to connect it to the old fuel line because it's a PITA to put in otherwise.
when i take the fuel line off the gas runs out just fine. there is no blockage in the fuel line.
 

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The resistance feels about the same as any other similar sized snow blower, not unusually hard to pull.
I agree with classiccats theory on low compression caused by a valve not seating or leaking head gasket. As the engine starts, some wheezing can be heard coming from the carb or muffler?? Good compression SHOULD make it a little harder to pull than what is now happening.
 

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if your going to pull the carb off of it again remove the cover behind it and check the valve clearance. These engine are know for losing lash on the exhaust valve due to valve seat wear. I think the clearance should be .008 but not sure. There are many videos showing how to grind the valve stem on youtube.
 

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Discussion Starter #20
I pulled it apart. The exhaust valve is not sealing and actually both intake and exhaust have no clearance in the valvestems, i couldn't get any size feeler gauge in so i'm going to lap them and grind them.
 

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