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Pull cord jerks when starting

Posted by malibuster MI (My Page) on
Fri, Jul 2, 10 at 13:56

I've inherited a lawnmower that won't start. First thing I did was check for spark and I have that. Fresh fuel in the gas tank and a fresh oil change filled to the right level. When I pull the cord it kicks back and almost rips my arm off and white smoke comes out of the muffler. I first thought it was the flywheel key but that looked ok but I replaced it anyway. I pulled the plug after the engine fired once and the plug was soaked with gasoline. What could be causing my problem. This is a Craftsman mower with a 5.5hp Tecumseh motor, model# TVS120-63920K

TIA!


Follow-Up Postings:

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RE: Pull cord jerks when starting

  • Posted by canguy British Columbia (My Page) on
    Fri, Jul 2, 10 at 17:23

Sounds like the engine is flooded. Does the oil smell like gas? If this is the problem the inlet needle is likely stuck, disassemble the carburetor and thoroughly clean it.Don't forget to dump the old gas and replace with fresh.Also change the oil.


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RE: Pull cord jerks when starting

Sounds like hydraulic lock to me. Pull the plug and spin it a few times, replace the plug and try again.


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RE: Pull cord jerks when starting

I got interrupted; anyway, if the mower is tilted up over 30 degrees with the carburetor down, oil can run into the intake tract. This will soak a paper air filter with oil and fill the cylinder with oil if it cathes the valves just right. When you spin it without the plug, make sure the plug wire is grounded or you could have a fire. It might be flooded with fuel as canguy says, too. Sometimes an old trick works on stuck floats - pick up the carb side of the mower and drop it a few times from about 6".


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RE: Pull cord jerks when starting

  • Posted by baymee LehighValleyPA (My Page) on
    Fri, Jul 2, 10 at 21:12

You know, I never thought about a fire shooting out of the spark plug hole !!! That would make a great you tuber.


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RE: Pull cord jerks when starting

Check that the blade is tight. Some of these engine have such a light weight flywheel that they depend on the blade for the energy to carry past TDC. IF the blade slips when the piston hits compression, they loose the energy.

Walt Conner


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RE: Pull cord jerks when starting

Hey guys thanks for the replies. I'm pretty sure it's not hydro-locked because I've had the plug out several times and the same result. That makes sense though with the inlet needle being stuck because it almost sounds like I might have too much fuel. I'll just have to read that Tecumseh Repair Manual, I haven't tore into a carb yet. This is a 15 yo mower and I'm sure that's never been off before.


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RE: Pull cord jerks when starting

The flywheel key is broken and your timming is off that is why the engine is mis-firing. DO NOT TRY TO START THE ENGINE" You must replace the flywheel key.


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RE: Pull cord jerks when starting

'I first thought it was the flywheel key but that looked ok but I replaced it anyway.'


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RE: Pull cord jerks when starting

The flywheel key was my first thought. That's why I spent $1.25 and replaced it first thing.


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RE: Pull cord jerks when starting

It sounds like the ignition is firing before the piston reaches top dead center. Does this motor have electronic ignition and does the ignition have a spark advance feature built in. If it does, the module could be firing in the advance mode. I've seen this happen on Lawn Boys.


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RE: Pull cord jerks when starting

IF it is not the flywheel key then the next thing I would check is the cam gear make sure it has not skiped a few degrees/teeth.


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RE: Pull cord jerks when starting

"It sounds like the ignition is firing before the piston reaches top dead center."

It will and it needs the blade to help with inertia to carry it thru as I said way above.

Walt Conner


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RE: Pull cord jerks when starting

I would look at what Rolm and Walt have suggested since the Severely Flood (Hydraulic Lock) situation seems to be a non factor when you have removed the plug and also replace the Key !


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RE: Pull cord jerks when starting

Check the blade adapter for a crack. Jim


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