Tecumseh engine Gurus....carb specialists

[Tim Frank]

Bought what appears to be an excellent used snowblower (but wayyyy bigger than I need).
Engine did not start, oil was clean, compression was OK, gas was cruddy, the guy was sure that it was gummed up over the summer, and knocked $50- off for the carb repair costs.

Cleaned the carb well, hit the starter and it fired up after 1/2 turn....more like a light switch than a starter button.

But, it will not run smoothly, it hunts like crazy.

The engine is a 12HP, OHV, and when I cleaned the carb I put a kit in that had the float needle and seat, welch plugs, and gaskets.
I also replaced the fixed jet tube and both o-rings.

I'm getting a lean spit-back as well as the hunting.
Been through the carb twice more, and if I scrub it any further I will be removing metal, there's no dirt left....

I've googled "Tecumseh 12 HP surging hunting" and it seems I am not the only one who has had problems with these fixed jet Tecumsehs; the old ones had the adjustable jet in the bottom of the fuel bowl.

Some suggest buying a new carb, but I am not sure what would be wrong with this one (apart from the obvious ~ the engine won't run with it) that would be right with a new one.

My other thought would be to see whether I could find an old-style carb that will fit.

Any suggestions?

 

[rbh]

Re: Tecumseh engine Gurus....carb specialists

Surging is usually a governor issue. let it off one position and see what happens, if nothing then tighten one position.
Hope fully it will improve one side or the other.

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

Surging is usually a governor issue. let it off one position and see what happens, if nothing then tighten one position.
Hope fully it will improve one side or the other.

Not sure that it is adjustable....
I thought of that...but usually the spring has several "optional positions"....not this one

 

[Cofe]

Re: Tecumseh engine Gurus....carb specialists

Not sure that it is adjustable....
I thought of that...but usually the spring has several "optional positions"....not this one

Does it have a spring that is wound around one of the carb linkages? Unhooking it and winding it tighter or loosening it changes throttle response on some motors.

 

[rbh]

Re: Tecumseh engine Gurus....carb specialists

OK, guess that's not it then.
Tecumseh HMSK80 surging - Tool Shed Forum - GardenWeb
Did you read this one yet??

 

[greenbush future]

Re: Tecumseh engine Gurus....carb specialists

Does the card use a diaphragm? Many times these are torn as a result of newer fuels.

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

No diaphragm.
I took it into a shop near home that is always very helpful. Happily they have an "Old Pete".....been fixing Tecumsehs for 40+ years.
He walked me through a couple of things i might have done more carefully....AND....noticed that the shop had sold me some incorrect o-rings last week.
Got it all back together with the correct parts and will try it in the daylight in the morning.

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

OK, guess that's not it then.
Tecumseh HMSK80 surging - Tool Shed Forum - GardenWeb
Did you read this one yet??

I've read that one, but they are obviously not as moderated as we are in here.
That thread just keeps getting added to in a really haphazard fashion....no resolutions really, just lots of questions.

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

Vroom vroom....

Thanks for your comments and ideas.
I think it was the o-rings that caused the problem.

 

[matt167]

Re: Tecumseh engine Gurus....carb specialists

Surging on a small engine almost always suggests a lean condition.. Tecumseh Snow Kings were great engines One of the last flathead industrial type small engines made.

 

[dolluper]

Re: Tecumseh engine Gurus....carb specialists

With those engines or most Tecumseh emission carbs it's the Orings or the idle screw that is capped ....it is unadjustable but does have a passage that cloggs up....take it out and clean the passage in the screw itself very small then snug it tight on install....also the bowl holding nut has two passages; both need to be cleaned out one is very hard to see right by the threads very small...

 

[Lone Duck]

Re: Tecumseh engine Gurus....carb specialists

With those engines or most Tecumseh emission carbs it's the Orings or the idle screw that is capped ....it is unadjustable but does have a passage that cloggs up....take it out and clean the passage in the screw itself very small then snug it tight on install....also the bowl holding nut has two passages; both need to be cleaned out one is very hard to see right by the threads very small...

Yup!! I use wd40 and strip a piece of 12 or smaller gauge automotive wire and unravel to one strand . poke it through the needle holes then blow with air.

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

The carb bowl nut actually has three holes....got them all....plus the idle jet cross hole.
It's working pretty well, but I think the plug wire insulation is breaking down.

 

[matt167]

Re: Tecumseh engine Gurus....carb specialists

I don't remember if the plug wire is threadded on those ( like an old Merc outboard in the distributor ). If it is, a small length of 440 packard and your back in business..

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

That would be really nice.
Just got the OEM manual for the engine, so will check it out.

 

[levittownnick]

Re: Tecumseh engine Gurus....carb specialists

Surging on a small engine almost always suggests a lean condition.. Tecumseh Snow Kings were great engines One of the last flathead industrial type small engines made.

My 8 HP Snow-Blower was doing the same thing and adjusted the high-speed mixture this morning prior to clearing today's snow (made the mixture richer, ccw). The engine ran like a charm. Thanks for the advise.

Nick

 

[Tim Frank]

Re: Tecumseh engine Gurus....carb specialists

Be glad you have an adjustable HS jet....

 

[Scott Danforth]

Re: Tecumseh engine Gurus....carb specialists

Do you have the carb heater box on it. They run lean without it.

 

[levittownnick]

Re: Tecumseh engine Gurus....carb specialists

Be glad you have an adjustable HS jet....

Amen.

 

[dolluper]

Re: Tecumseh engine Gurus....carb specialists

They can run funcky when the exhaust collapse inside.Stick a screwdriver through the holes in muffler to see if plate blocking restricting the exhaust,just like a lean condition when it happens...seen this a few times