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Murray (briggs and stratton) mower


sparky's Avatar
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Join Date: Sep 2000
Posts: 37
VA

08-31-01, 06:55 AM   #1  

I have a Murray brand lawn mower that has worked great
for the past 7 years.
Recently the engine is cutting out after starting under
the following conditions.

1. run mower for about 20 minutes
2. mower shuts down
3. mower starts but shuts down after 3 seconds.
4. wait about 3-4 hours, mower runs fine.

Thanks,
Ron

 
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Frosty's Avatar
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08-31-01, 11:04 AM   #2  
Frosty
Check your air filter for clogging, if you haven't already done this. But it most likely sounds like you have an electical problem. Inspect the spark plug wire for cracking. It could be that as the wire gets heated from engine operation (about 20 min in your case) it expands and creates a gap in the wire. When this happens electricity is no longer making it from the magneto to the plug because of the gap. Once the engine cools down, the gap in the spark plug wire contracts and the mower is able to start again. If cracked, it will need to be replaced.

Maybe others will have more ideas for you.

Best of Luck!

 
Fisher's Avatar
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08-31-01, 11:27 AM   #3  
Fisher
Sounds like a valve problem. To adjust the valve gap on
your mower, you need to remove the valves, so you might as
well have a proper valve job done.
Fish

 
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Join Date: Feb 1998
Posts: 10,440
CAL

08-31-01, 01:54 PM   #4  
Restricted Gas Cap

Hello Sparky

Frosty has offered you some excellent advice with the mentioning of a defective spark plug wire and possibly restricted air filter.

You'll also need to check for a restricted fuel supply. It's possible the fuel tanks gas cap has a restricted vent.

To check this, remove the fuel line from the carb. Watch the fuel flow rate while doing this. If it diminishes over time as it is coming out, the vent hole may be restricted. If it stops totally, the vent hole is pluged. If all the fuel empties out, all is okay here.

If there is a restriction or blockage in the vent hole in the gas cap, the tank will drain until it pulls a vacumn in the tank. Then the fuel will slow down until it stops flowing.

Once you OPEN the cap or allow enough time to pass, the engine restarts because the tank once again gets air in it.

Another possibility is a restricted exhaust. A damaged or overly rusted muffler may have internal damage causing an exhaust restriction. Exhaust restrictions can cause several problems. Overall poor engine performance, excessive engine heat, failure to accelerate properly, hard starting, rough running and many more.

Engine overheating could be a factor. In order to remedy this problem, you'll need to verify there aren't any cooling air flow restrictions. Remove the starter housing cover off and clear out any debris under the cover, along the entire air flow path and on the cyclinder head.

If there is rust is on the cyclinder head, engine case fins or in between the cooling fins on the cyclinder head, wire brush off as much as possible. Inspect inside the flywheel cover also.

Check the archives, within this forum, for other postings and replies on this topic and the manufactures online web site for further information.

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

 
darrell McCoy's Avatar
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08-31-01, 02:58 PM   #5  
darrell McCoy
Some older Murray's had a vent on the gas tank lid that you had to open. Turn CCW.. Never did understand the purpose of this.

 
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