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grump


Joined: Jan 14, 2008
Points: 56

Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Original Message   Feb 23, 2014 6:13 pm
Old Ariens with a HSK70 engine (original was H70), starts right up and throws fine with the throttle wide open.... until it gets to work hard then it quickly just dies. 

I release the belt tension, can start it right up again, and ease the belt into position while it clears it's load.  Then it's business as usual until the next big load is encountered and it dies.

What could be going on?  It's always been easy to start by hand and there's Stabil in the gas.

My assumption is that it needs to run richer, but since it starts so readily hesitate to change the needle setting.
Replies: 5 - 14 of 14Next page of topicsPreviousAllView as Outline
grump


Joined: Jan 14, 2008
Points: 56

Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #5   Feb 25, 2014 1:40 pm
That may be all it needs, then.  Great!

Thinking about some of the comments and how it behaves, I'm using it at full throttle and not truly overloading it but am expecting a lot from it.  Like everyone else, we've had a lot of snow.

At full throttle it dies under heavy load instantly.  It used to slow down and every bang bang bang of the engine firing could be heard and it recovered, but it didn't stall.

I can readily remove and spray the passages for both needles, what changes should be make to either's setting? 

Tough call for inexperienced me as I can't readily replicate a load to see how it acts, and if we're lucky won't know if it's really fixed until next year!

Thanks.
jrtrebor


Location: Michigan - 3 hours north of Chicago on the lake
Joined: Feb 10, 2010
Points: 524

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #6   Feb 25, 2014 3:04 pm
grump wrote:
At full throttle it dies under heavy load instantly.  It used to slow down and every bang bang bang of the engine firing could be heard and it recovered, but it didn't stall.

I can readily remove and spray the passages for both needles, what changes should be make to either's setting? 

It simply sound like you've got a dirty carb.
The fact that it used to perform better than it is now.
Sounds like you've got a dirty fuel system.
A fuel filter should pick up stuff coming out of the tank.
But it won't filter out everything.
You can build up debris in the fuel bowl itself.
Small bits of varnish, small amounts of water. Tiny, tiny bits of rust scale if you have a steel tank. .
It only takes a any extremely small particle to cause problems in a carb.
If you haven't messed with the carb yet.
I would simply try opening up the needle on the bottom.
An 1/8 to a 1/4 of a turn (clockwise) and see if that makes any difference.
Just spraying, usually won't fix things.  You have to remove the main jet and
run a small wire into all of the small passages.
This link will show you some photos of the small passages.


This message was modified Feb 25, 2014 by jrtrebor
RedOctobyr


Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 273

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #7   Feb 25, 2014 3:24 pm
jrtrebor wrote:
If you haven't messed with the carb yet.
I would simply try opening up the needle on the bottom.
An 1/8 to a 1/4 of a turn (clockwise) and see if that makes any difference.

You're the expert, not me :) But if viewed from below the bowl (so you could see the head of the screw for the needle), wouldn't you typically turn it counter-clockwise to open the needle, and allow more fuel to flow?
RIT333


Joined: Jan 3, 2008
Points: 19

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #8   Feb 25, 2014 4:14 pm
RedOctobyr wrote:

You're the expert, not me :) But if viewed from below the bowl (so you could see the head of the screw for the needle), wouldn't you typically turn it counter-clockwise to open the needle, and allow more fuel to flow?


That is what I was going to say.  The screws control the fuel flow, so, turning it "out" (CCW) will allow more fuel to enter. 
jrtrebor


Location: Michigan - 3 hours north of Chicago on the lake
Joined: Feb 10, 2010
Points: 524

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #9   Feb 25, 2014 5:01 pm
You're both correct.
I probably should have been clearer about that
I assumed that that carb was still on the engine.
So looking down at the carb. and reaching underneath the bowl.
You'd be turning it CW to increase the flow.
mkd55


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

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #10   Feb 26, 2014 10:40 am
turning the high speed screw counter clockwise or out as if you were trying to remove it will increase the fuel mixture.
grump


Joined: Jan 14, 2008
Points: 56

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #11   Feb 26, 2014 7:05 pm
I'll check the fuel bolt for crud in the passageways and set the adjusting screw a tad richer. 

Be great if that's all it takes and thanks for guiding me in the right direction.

Will post back how it goes after the next major storm, hopefully in a few years!
RedOctobyr


Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 273

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #12   Feb 26, 2014 8:29 pm
I'm trying to think of how you could test it, without having to wait for another big snow (and *then* find out you still have a problem).

You might try putting it in gear and trying to fight it, as it drives forward? Or putting it up against something solid, and letting it (briefly) try and drive itself forward might also work. Don't do it for long, though, as you'd be making the friction wheel slip.

I wonder (jrtrebor, etc, please tell me what you think)- could you run it at idle, then briefly rotate the actual throttle lever by hand, forcing it to open the throttle fully? You could only do this very briefly, as with no load, the engine would quickly over-speed, and could be damaged. Assuming it doesn't simply stall, of course. But it might be a way to make it use the high-speed needle, rather than the idle?

If this is just a stupid idea, then please tell me. I'm just trying to think of ways he could try and test it, without having to wait until he actually needs it.
jrtrebor


Location: Michigan - 3 hours north of Chicago on the lake
Joined: Feb 10, 2010
Points: 524

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #13   Feb 26, 2014 11:29 pm
RedOctobyr wrote:
I'm trying to think of how you could test it, without having to wait for another big snow (and *then* find out you still have a problem).
You might try putting it in gear and trying to fight it, as it drives forward? Or putting it up against something solid, and letting it (briefly) try and drive itself forward might also work.

You could try putting the bucket up against something that won't move.
If you have a smooth concrete floor in a garage would be a good place;
The tires should be able to spin on that surface.
Run the throttle up put it in first gear and engage the drive.
That would put a decent load on it.
If he's going to clean the carb out.
Then he'll have to reset the needle from scratch. And adjust it with the engine running.
You do the initial setting by slowly screwing
 the needle all the way in, and stopping when you just start to feel a little resistance.
That is it coming in contact with the seat.
Then you back it out 1 1/2 turns.  That is your initial setting or starting point.
You start it, let it warm up.
Then run it up to full throttle. You start turning the needle in slowly until you hear the engine start to drop in RPM.
Then you turn it slowly the other direction (opening it up) until the engine again starts to sputter or drop RPM.
Then you turn the needle back in to set it between those two points.
So if you turned it in a half of a turn.  Then turned it out a full turn.  You would then turn it back in a 1/2 turn.
That's the static way to set it (no load).  Which will usually work out pretty well.  If the carb is good and clean.
Of course if when you put a load on it, and it doesn't handle it well.
Then you would need to open the needle up a little more. Until it does.
mkd55


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

Re: Tecumsh simply shuts off under a heavy load... lazy snowblower syndrome!
Reply #14   Feb 27, 2014 1:28 pm
to test the carb high speed to see if it's rich enough all he has to do is start it up stone cold and observe how it acts. i've set my 8 hp tecumseh up to start with the choke full on, throttle full high speed,prime the bulb 2 to 3 times and pull the cord. once the engine starts almost immediately (within 2 to 3 seconds) i can take the choke all the way off. how rich you set the high speed needle will determine how much choke the engine needs to stay running from an initial stone cold start. the leaner the high speed jet the longer the engine needs the choke when started cold to stay running. by having it a little rich it will start better in extreme cold, there will be less fussing with it when it starts and it will run cooler .
This message was modified Feb 27, 2014 by mkd55
Replies: 5 - 14 of 14Next page of topicsPreviousAllView as Outline
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