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grump


Joined: Jan 14, 2008
Points: 58

Stalling under load; Tecumseh HSK70 7 Hp
Original Message   Dec 20, 2008 10:13 am
Have an HSK70 7 hp engine that's been used about four years which is  mounted on an everlasting and loved old Ariens chassis from 1971.

Ran great until first use this season.  I'll preface this by stating that last spring I shut off the fuel line and drained the carb.  It's the first year I've done so little for seasonal storage.  There was about 1/4 tank of fuel.  The snow blower has seen light use with only one curb cut and 20' of driveway.  My estimation is maybe 16 hours of use.

This year I filled the tank, it started right up and made it about 100' from the shed to the driveway.  There's where the problem began.

It stalled under load.  Ran fine at idle but as soon as I engaged the drive belt and demanded something from it; stall.  Setting the choke to 1/4 (the first notch) seemed to help, but the problem persisted.  I tried tweaking the needle adjustment on the carb.  It started at 1 5/8 turn from a gentle bottom, and seemed to run best at that position.  I tried tweaking it both with the drive belt engaged and disengaged.

It idles fine but just plain stalls under a load. 

What should I do?
This message was modified Dec 20, 2008 by grump
Replies: 5 - 14 of 14Next page of topicsPreviousAllView as Outline
grump


Joined: Jan 14, 2008
Points: 58

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #5   Dec 21, 2008 11:44 am
Success!!

Took off the carb bowl and found some specks of black crud that looked like fuel line material.  Quantity wise maybe two shakes of a typical salt shaker.

Inspected the bolt with the two holes.  The larger was visibly open, the smaller looked OK but I ran a single strand of wire from an electrical cord through it and wanting to be compulsive about it used a neighbors compressor to blow it out.  I think it was OK to start with but that small hole; well I guess anything can impair it.

Ran a few ounces of fuel through the carb into a jar while it was open and it came out clean.  Polished the needle just a tad with an SOS pad, probably not the right thing to do but I rinsed and dryed it well.

Hardest part was getting the float needle part back on with the open end of the spring facing the air intake.  It didn't want to stay under the lip on the float (which inspected AOK) but eventually went into place.  Am sure with practice it'd be easy.

While I had tools out I cleaned the spark plug and closed the gap a bit to .030

Ran it through the hardest packed curb mound I could find and it didn't hesitate a bit.  Let is run awhile (admittedly admiring how well it's doing) and ran it through some more packed curb snow. Just like new.  Will check it in awhile for any leaks I might have missed.

Am going to change the fuel line, check that the tank is spotless, and have a carb gasket onhand just in case this happens again. 

Is it advisable to add a fuel filter to this, or would that impede something?

Thank you many times.
ExCompost


Joined: Jan 1, 2009
Points: 2

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #6   Jan 1, 2009 11:20 am
Thanks Grump, Frily and everyone else for this thread.  My 20+ yr. old Ariens w/ a 7 hp Tecumseh and bowl carb had the same problem of faltering and stalling under load.  It took a rebuild kit and cleaning of the idle and main jets w/ copper wire to solve the problem, and a cutting and tightening of the governor spring to the throttle plate seemed to help.

One of you mentioned removing the main fuel jet and inspecting it.  Do you mean the passage that runs up the center of the carb body and protrudes into the throat between the choke and throttle plates?  Can that te removed?  If so, please let me know how to do it for future reference.

Do you guys think that 87 octane works ok w/ these older engines, or is mid-grade or premium recommended?   Thanks a lot and Happy 2009.

MacLorry27


Joined: Dec 23, 2008
Points: 54

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #7   Jan 1, 2009 11:59 am

ExCompost,

87 octane works well in all these small engines, however, you want to avoid gas that has alcohol in it, as it does in many states. Newer engines can handle it, but alcohol attacks rubber and plastic parts that have not been formulated to withstand it. Where I live I buy premium alcohol free gas for all my power equipment even though the 91 octane is not needed. It’s only sold at a few gas stations as it’s not legal to put it in cars (other than classics).

Mac

mkd55


Location: wisconsin
Joined: Dec 16, 2005
Points: 153

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #8   Jan 1, 2009 5:28 pm
excompost!! if your carb is like the illustration in the post above it has the main jet screwed  into the bottom of the brass  high speed bowl nut that holds the float bowl on. to remove the nut  just turn it out counterclockwise with the appropriate wrench. once out you can inspect and clean the two holes. make sure you don't bend the float tang.the bowl gasket is in place, and the needle is hanging off the float tang where it should be, and the indent or sloped side of the bowl position is noted and positioned in the same place when you put the bowl back on. i believe there is a little dent in the bottom of the bowl facing up and that needs to be under the float so the float can't stick to the borttom of the bowl if it runs dry and is left like that. the float then rests on the dented bump rather than the full length of the bowl.
This message was modified Jan 1, 2009 by mkd55
ExCompost


Joined: Jan 1, 2009
Points: 2

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #9   Jan 2, 2009 10:47 am
Hi mkd,

Thanks for the advice on positioning the bowl, as I wasn't sure where in relation to the float to put the deep or dented end.

In my earlier question, I was referring to part 11 on the diagram, the fuel well spacer, which appears to be permanently installed in the carb body.  The jet screw and the bowl nut are no problem to remove and clean.  What's your take on using reformulated regular (10% ethanol) or higher octane gasoline, such as we use here in NH?

mkd55


Location: wisconsin
Joined: Dec 16, 2005
Points: 153

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #10   Jan 2, 2009 7:18 pm
i have been running no more than 10% blend for a few years now in my 1986 tecumseh ariens 824 8hp, so far no ill affects. the spacer has a larger orafice than the brass jet nut so if anything is going to clog it's the holes in the nut. i found out the hard way about clogged jets on a new 40hp evinrude two stroke outboard. the bottom carb high speed jet had a piece of gasket clogging it that worked loose when it was assebled when new. i ran it on one cylinder back to the landing probably five minutes max. it's a 1987 motor bought new and in 2001 i had to have the cylinder head rebuilt with the bottom cylinder bored and a new piston and rings. i t took me a while of thinking why the cyclinder went bad and i figured a did some damage when the jet was plugged. if you have no gas you have no lubrication for the cylinder either. the boat gets used in canada once a year and thats it and i'm still going every year and have had no problems since. nock on wood!

grump


Joined: Jan 14, 2008
Points: 58

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #11   Jan 18, 2009 9:14 pm
Original poster here.  It's still running like new, just flawless in today's storm and a pleasure to use.  Thanks again for leading me in the right direction.

Was hoping to find an answer about adding a fuel filter to minimize chances of another clogged jet.  I assume there is an engineering reason why it didn't come with one back in the 70's, but is it OK to add a small one just before the carb?
borat


Joined: Nov 10, 2007
Points: 2692

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #12   Jan 18, 2009 9:34 pm
No reason I can think of to not install a fuel filter.  I'd put it between the shut off valve (if it has one) and the carb.  I wouldn't go too small.  I like to use the $3.99 Canadian Tire clear plastic filters.  They're big enough to provide many years of service yet small enough to install in limited spaces.  Being clear plastic, it's easy to see if it has contamination in it.   
niper99


Location: London Ont
Joined: Dec 2, 2007
Points: 337

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #13   Jan 18, 2009 9:50 pm
grump

yeah defintly add the the fuel filter it will save u a lot of headachs in the future. tecumsech uses a "so called" fuel filter in the gas tank but alot of times people break them open when they clog up from years of service.

grump


Joined: Jan 14, 2008
Points: 58

Re: Stalling under load; Tecumseh HSK70 7 Hp
Reply #14   Jan 18, 2009 10:23 pm
OK, thanks.  Will do. 

Suppose there's no reason to use a small one as I envisioned because a larger one will have less resistance to the gravity fed carb.
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