Sears 11hp tractor hard to start

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  #1  
Old 08-01-05, 01:12 PM
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Sears 11hp tractor hard to start

I recently purchsed a 11hp briggs Sears LT-11 lawn tractor which is quite hard to start. While turning the key, i have to move the throttle down to the bottom, up, then down again, and when it fires, i slowly move it back up to keep the engine running. It takes a few turns of the key to get the engine started. When the engine finally starts, it runs great. It runs smooth at any speed, but when I turn it off, I can not get it started again for about 15 to 30 minutes, if i'm lucky.

I'm worried about killing the battery. The person I purchased it from just bought a completely new battery before he delivered it.

Any ideas? I do know engine talk, because I took small engines in high school.
 
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Old 08-01-05, 01:35 PM
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i had an sears lt 10 that was giving me fits last yr and the beginning of this yr. it acted the same as yours. after rebuilding the carb, replacing all the ignition parts new, and popping the head to set the magneto timing (it was points), it came down to the fact i was sold a bad coil or condenser or it went bad again when it got hot. the blower housing would crimp the spark plug wire. i changed to an old magneto and blower housing ending mos. of agony. i also have an old murray that acted similar to yours when the coil was going bad. it would run 45 mins. get hot wouldnt start till cool. then it was 22 mins. then it was 10mins. i had to buy another coil. my guess your engine is solid state and needs another coil.
 
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Old 08-01-05, 01:41 PM
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Could it also be the points? I also acquired a 79 lawn-flite 8hp briggs that wouldn't start at all. I filed the points, and boom, started easy and great, considering it sat out in the weather all winter!

I forgot to mention one thing. When the engine is running, if I move the engine speed too fast from idle, it'll start to sputter and stall.

There is only a few years difference between the two. the sears is an 82. Could cleaning the points help me start easier?
 
  #4  
Old 08-01-05, 09:58 PM
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the sputtering from low to hi speed is carb. turn hi idle screw back out 1/2 turn counterclockwise to richen mixture. i also spray carb cleaner around outside of carb to see if it affects rpm to ck for vacuum leak. i have had intake gasket get leaky before and cause stalling under load. on the sears ck compression when hot by seeing if engine turns over more freely when hot. if it does and your still getting good spark then suspect tight valves. it involves pulling the head and valve cover. rotate piston to tdc on compression stroke. both valves should be fully closed with .005-.007 intake clearance on briggs between valve stem and lifter and .007-.011 on exhaust. tecumseh varies but .005 on intake and .006-.010 is ballpark. compression stroke is after intake open and piston goes to top of cylinder and before exhaust opens. this symptom occurs on older engines when the valve seats become worn. my lt 10 is a 1979 model. on my mowers it appears 1980 was the transition yr from points to solid state ignition. 1982 should be solid state. i have lapped and ground my own valves using crude means with no problems. i have had intakes with little clearance quit sucking gas when hot and tight exhaust valves cause engine to run hot. both cause hard or no start when hot and loss of compression when hot. if it is still as difficult to rotate the flywheel when hot as it was when cold suspect ignition.
 
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Old 08-02-05, 12:29 AM
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Hello James Sanders!

I agree on the valve clearance theory. Your symptoms sound like classic symptoms of tight valves (too little clearance).
 
  #6  
Old 08-02-05, 10:39 AM
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Ok, Later on tonight, i'll adjust the carburator, cut the lawn, and check if the engine moves freely when i'm finished. I'll probably check the valve clearances anyway, because I like doing this kind of stuff.

I'll report back on what I find.
 
  #7  
Old 08-08-05, 01:37 PM
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Stalling while cutting.

Today, I adjusted the carb 1/2 a turn and it starts within a couple of seconds. I didn't bother to check the valves.

I started to cut the lawn and after about 20 minutes, the engine starts to sputter, like it is about to run out of fuel. I lowered the throttle, and it smoothed out. I then raised the throttle back up to normal posisition, and it runs fine, for a little while. (It also starts to sputter later on when I engage the blade. Again, moving the throttle down and up fixes this)

Maybe about 5 min later, it just sputters and then completely stalls. Throttle can't fix this. It then will not start at all until it has cooled down for about half an hour.

A neighbour has suggested that I sand the points, which I am going to do anyway (I had a similar problem on the same year engine and cleaning the points made it run better)

I am also going to reset the idle and main jet screws and clean the fuel bowl. I turned the idle screw in and it was about 3 1/2 turns. I think this is too much. 1 1/2 - 2 turns should be the right setting, am I right?

I will report back to see if there is any improvement. If there is none, I will check the valves to see how tight they are. This is really annoying because I use this tractor with my job cutting customers lawns and stalling in the middle of the cut isn't good! I work around this by using a push mower and doing the edges, around the trees, etc, until the tractor cools down )
 
  #8  
Old 08-08-05, 02:17 PM
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Sounds as though now you have adjusted the carb to where it is a bit too lean. Documented settings are for initial adjustments, usually only small adjustments from the initial settings are and should be needed. Adjust the high speed with the engine at full throttle, adjust in CW until the engine begins too sputter this is best lean mixture. Turn out CCW until it smooths out, keep going until it again starts to sputter. Now find the spot between these extremes. Move the throttle to idle, then to full throttle, if it hesitates adjust the idle mixture CCW. Finally set the idle speed.
One other thing to check for the hard starting is that the blade belt is not putting any pressure on the crankshaft pulley. I would also agree tho that on that old of an engine the valve clearance is in need of attention. Try removing the deck belt and see if it starts easier. If so and the deck belt is correct and the spindles are ok, valves are easy nuff to do.
 
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