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Garden Tractor Shutting Off


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07-31-00, 12:49 PM   #1  

I own a 1985 Sears 18 HP Garden Tractor. When the tractor is cold it starts immediately. Once you run it for about one hour it shuts off with no warning. If you try to restart the tractor it will crank but will not turn over. The only way it will start is to leave it cool down for about 45 minutes. The most recent repairs include new plugs, air filter, gas line filter, oil change and V-Belt. Any suggestions would be appreciated.

 
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07-31-00, 08:12 PM   #2  
Hi:Spooky

A few things you could check for.

Be sure there isn't any restrictions in the cooling air flow over the engines cooling fins. Even if it cranks after overheating, an engine of this age may not totally seize up if overheated.

When it shuts itself off, check for spark at the spark plug. May be the ignition module shuting off from excessive heat.

Book also mentions vapor lock. Could be the engine running too hot and boiling the fuel, either in the fuel line or carb.

Fuel mixture screws may need to be adjusted. The engine may be running too rich <explains an easy cold start> or too lean at high speed <which may cause it to run too hot.>

That 45 minute cool down time does sound a lot like an overheated ignition system. Verify the spark at the plugs first.

Post back the results of your findings.

Good Luck,
TomBartco
Accurate Power Equipment Company.
Small Engine Service and Repair Technician.

 
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08-01-00, 06:01 AM   #3  
mikejmerritt
I agree it sounds like ignition.If the you have fire after the engine quits and it will still crank smoothly,loosen the gas cap to see if there is a hissing sound.If it does I bet it will start.If you could be so lucky replace the cap.

 
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08-07-00, 07:47 PM   #4  
After checking several items on my 1985 Sears 18 HP Garden Tractor it appears that it does not have any spark when the engine shuts down. I have been advised that the points/condenser are possibly bad. The Sears manual lists two parts for the starter motor group. The trigger coil assembly magnatron ignition and the armature assembly. Where would the points/condenser be located or should I replace both parts? Any advice would be appreciated.

 
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08-07-00, 08:26 PM   #5  
Hi:Spooky

It's most likely the points and condenser. If you want to change them yourself, they are located under the flywheel.

I do not recommend you attempt to remove the flywheel without using the correct puller. Those flywheel fan coolers are made of pot metal and damage easily.

If you do remove the flywheel, the points and condenser are located inside a metal compartment around the crank shaft end.

TomBartco
Accurate Power Equipment Company.
Small Engine Service and Repair Technician.

 
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06-05-05, 07:55 PM   #6  
spooky2
tractor wont restart when hot

hey spooky - I think I have the same twin cyl 18hp tractor with the same problem. I bought it from a friend who warned me about this condition. 45 mins is about the right time frame. Last time it happened I popped the sparks after 30mins and dropped a teaspoon of gas in each. It started up smooth and finished the day, possibly proving it is a fuel delivery issue.

The next time it happens I will

1) loosen the gas cap
2) undo the fuel filter and check for fuel in the line

if the gas cap cures it then I think one of your respondents is right
if the line is dry then I am thinking the fuel pump might be involved.

before yours shuts off does it throb before shutting down ??( like its out of gas)

 
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