John Deere LX279 running issues

searlesy

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Mar 15, 2018
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Hi All, new guy here from Australia.

I have a John Deere LX279 that is having a few issues.

It starts and runs fine, but after a while develops a bit of a miss sometimes, which today, turned into more of a miss, then started hunting up and down the revs. Without the blades on it runs fine, it seems as if once it gets a warm, something is causing extra resistance on the blades that is causing the issue?

I have checked the obvious, nothing caught up in the pulleys, nothing in/around the blades. It seems as if there is a problem with the blade drive system that kicks in when it gets hot. Whilst I have never worked on a mower before, I am mechanically minded, and can happily work on motors and mechanical systems, but does this sound like an obvious/common problem that I might be able to fix?

Thanks in advance,

Matt
 

bertsmobile1

Lawn Royalty
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Nov 29, 2014
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Your engine runs at 3500 rpm when you have it set on fast which is oft called "High Idle or Fast Idle"
It is called that because the throttle butterfly is almost closed.
When you put a load on the engine, the speed drops so the throttle butterfly opens up in order to maintain a constant speed.
More air will of course need more fuel and if there is a partial fuel blockage the engine will miss.

Start the engine , set the brake then get off.
Slowly move the governor lever to make the engine speed up.
If it starts to miss then you need to pull the carb off & clean it.
Replace the fuel filter and check you are getting full fuel flow from the tank.

There is also a solenoid on the bottom of the carb.
hold it between our fingers when you are increasng the engine speed.
If you can feel it clicking on & off then the wires connecting it to the engine are suspect.
 

searlesy

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Mar 15, 2018
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Thanks for that, I will make some investigations, and see how I go!
 
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