Tecumseh engine running rough

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  #1  
Old 02-07-04, 03:49 PM
rick31797
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Tecumseh engine running rough

HI everyone, i am from Canada, looking forward to using this sight.

I have a Roper snowblower with a 10HP tecumseh engine .This thing has to be close to 30 yrs old, and its starting to die on me.

It seems to run fairly good at the start, but then as it warms up, it starts to run rough and also i see sparks coming out of the Muffler once and awhile..
This is probably a sure sign of something But What??

I put new plug in it ,changed the oil and a new fuel filter...

I also notice the plug wire is resting close to the muffler and has not burnt through yet, but you can see, the outside is melted...
I will need to get something to cover it in the future..

Thanks Rick
 
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  #2  
Old 02-07-04, 04:17 PM
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It is probably running lean. Remove the bolt at the bottom of the carburetor's float bowl and clean it out. It has one or two small holes in the side of that bolt which needs to be cleaned spotless. They probably just got clogged from bad fuel/trash over time. This should solve your problem.

Here's a link which explains it well:
http://www.lawn-mower-shop.com/carb1.htm

If that doesn't solve your problem, then back the fuel mixture screw out a little until it runs better. Hope this helps!!!!!!!
 
  #3  
Old 02-07-04, 04:45 PM
rick31797
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Thanks

I will try that tomorrow and clean it up good...Thanks for all your help/.//this web sight is Awesome"
Rick
 
  #4  
Old 02-07-04, 11:32 PM
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Hello Rick!

Check the carburetor, but on an engine that old and with the symptoms you describe, it is a good bet that the valve clearances need adjusting.
 
  #5  
Old 02-08-04, 06:37 AM
rick31797
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Valves, sound like a major engine tear down...I have no idea how to adjust Valves.Is this something a person can do or is it better to have a shop handle it.?
 
  #6  
Old 02-08-04, 08:38 AM
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rick
Foryour model it should be .008-.012 clearance (cold) for both valves. To check this it's actually quite simple. With the piston at TDC during the compression stroke, take a feeler gauge and measure the clearance between the lifter and valve. You'll have to remove the vavle cover to check this.
Normally a good valve lapping can bring the valves back to within the specs needed.
If you're not experienced it may be a shop job but if you are inclined to try it we can do all we can to help you through it. I would recommend before going much further to pick up the Tecumseh Mechanics manual. It explains all the stuff you'll be trying to do in very good detail. Highly worth the money.

Hope this helps.

snoman
 
  #7  
Old 02-08-04, 09:29 AM
rick31797
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I am the kinda guy that. will try almost anything , and sometimes it s bid screw up and others times..i surprise myself.
I know a bit about motors...but not alot about small engines.
The Valve cover, i have no idea where that would be.On this motor.. do you need to take the head off.

If The Valves are bad and that is what is wrong i probably wont do anything tell it gets warmer..I really wish i had heated garage.
Rick
 
  #8  
Old 02-08-04, 09:54 AM
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rick
If you look directly behind the carb, you'll see a cover approx 1 1/2 " by 3" thats the valve cover. It's probably easiest to remove the carb/intake manifold before. As long as you know when the compression stroke happens you won't have to remove the head.

snoman
 
  #9  
Old 02-08-04, 03:00 PM
rick31797
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hi

I took the Fast idle screw out of the btm of the float cover and cleaned it all up..I believe that is what was meant by the first post...and that didnt seem to make any difference...

I Adjusted the Fast and slow idle screws..The manual says to turn the screws in tell they seat and then turn out one complete turn and start engine..Adjust the fast idle tell engine runs smooth and then turn counter, clock wise 1/8 of a turn , so the engine will run a bit rich too help when its under load..

Like before..after the engine was running for 15 mins..it started acting like it was starved for gas..

I did notice that when the snowblower was underload it work , not too bad...as soon as you stopped the impellers, and the engine was running at high idle...it started to act like it was not getting gas.
I also notice that if i moved the choke in slightly it seem to run better..( less Air)

I think the Carb really needs a going over...hasnt really been touched, but when it gets nicer, i will also take a look at the valves..
I am confused that it seem to run pretty good when it was underload.and not so good when it was at fast idle." Not under load..
Rick
 
  #10  
Old 02-08-04, 04:02 PM
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rick
That sounds odd cause when it's under load, it requires more fuel and that's when it should run bad (starving). I have a few things that I do before the machine is even started and that is to make sure I have a healthy spark, I made a tool to see if the spark will jump at least 1/4 " next I reset the governor system to make sure that when I get under load the rpms will compensate the differential. Since you say it runs seemingly better when you close the choke a bit then I would say that it requires more fuel. That is achieved by turning the high speed needle counter clockwise.
Last but not least is when I first fire up an engine, I set it to top rpms and bring out the vibra tach and set top end at 3600 rpm. sometimes if you are a little lower in rpms, the high speed will not make the fine adjustments that you may require.
Hope this helps more than confuse you.

snoman
 
  #11  
Old 02-08-04, 04:30 PM
rick31797
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HI

This is very helpful information ...I know i need to take a good look at this machine..and when the weather gets better i will go through the steps to get it running better.
I will take the Carb off and clean it really good and look at the valves at the same time.I also need to replace the spark plug wire, and maybe look at the points and Magneto.
Really there is much to make it run when you think about it...Nothing like a car engine.

Why it runs better under load i have no idea...When it is running rough and you put it unload it should stall...instead it smooths out.

Thanks
Rick
 
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