# John deere 620 runs and dies?



## green70d (5 mo ago)

Hi
I have a friend who has a 620, it starts good and runs about ten seconds and dies. Then you can start it right back up and it dies again. So far we have changed points, condenser, a new coil. It's getting fuel as well. What else can we do? Thanks for any help.


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## BinVa (Sep 21, 2020)

JD 620 is a pretty simple tractor. If you're getting a consistent spark and timing is correct...I'd check for debris in the carburetor or fuel line. Are the plugs wet or dry after a start and stall? If wet...could be an air intake restriction...if dry .. a blocked carb jet. B.


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## bmaverick (Feb 20, 2014)

green70d said:


> Hi
> I have a friend who has a 620, it starts good and runs about ten seconds and dies. Then you can start it right back up and it dies again. So far we have changed points, condenser, a new coil. It's getting fuel as well. What else can we do? Thanks for any help.


Sounds more like a carb issue of air and fuel. 

Is this a regular gas engine or the 'all fuel' engine (aka diesel like)


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## Bertrrr (Jan 28, 2021)

It's almost always the fuel system when this happens, ignition rarely behaves like this


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## 2billt (Aug 7, 2011)

Throttle in fixed idle position during start and stall?


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## Busted Tractor (May 22, 2018)

Before you overhaul the whole tractor for a simple fix---Turn on the switch and check for voltage at the coil. 0? should be about 6 volt I believe. Now step on starter tractor starts runs until starter is released right?
What's wrong? JD uses a starter bypass to help starting as long as the starter runs you have battery voltage to the ignition coil When the starter is disengaged a reduced voltage circuit takes over.
What do I look for? remove dash, check for a resistor block, check power from switch to resistor block the check voltage from resistor block to coil. You might also check resistor block with an ohmmeter. 
By the way if you crawl under tractor and remove the flat plate covering the starter you will be able to see the 12 volt bypass wire on the starter switch. It is only activated when the starter is
Hope this helps and makes the repair easy.


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## Tx Jim (Jul 28, 2020)

Ditto what Busted Tractor stated. 620 ign switch in start position supplies 12 volts to points for easier starting then switches to 6 volts for operation. Check to be sure one is getting 6 volts to points when switch is in run position.


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## Busted Tractor (May 22, 2018)

Tx Jim said:


> Ditto what Busted Tractor stated. 620 ign switch in start position supplies 12 volts to points for easier starting then switches to 6 volts for operation. Check to be sure one is getting 6 volts to points when switch is in run position.


Those old 2 cylinders. When the switch was turned on supplied 6 volts to the coil, the switch went thru a resistor. The x20 series and prior you stepped on a pedal to activate the starter doing so bypassed the resistor and when you stopped using the starter it opened the bypass circuit.. This is also why the tractor would start when the starter pedal is depressed and stop when the pedal is released. Note the x30 series used a push button not a pedal but still worked the same


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## BinVa (Sep 21, 2020)

Interesting information about the 12v start..6v run. I kept a 520 for the better part of 30yrs. and never realized how the system functioned. I believe I may have had the starter rebuilt and the start switch replaced…but never any electrical issues. It was sometimes the only tractor that would start in the dead of winter. B.


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## Busted Tractor (May 22, 2018)

BinVa said:


> Interesting information about the 12v start..6v run. I kept a 520 for the better part of 30yrs. and never realized how the system functioned. I believe I may have had the starter rebuilt and the start switch replaced…but never any electrical issues. It was sometimes the only tractor that would start in the dead of winter. B.


I often say I was raised by John Deere but made my living off of Minneapolis Moline and Massey Ferguson.
Dad had a 46 A, a 48 A, 56 70 diesel, 58 520, a 65 110H, a 48 8N and an 48 AC G. Of those the G is in my shed and the 520 is in mom's shed. Started driving too young and kept up until I went to work. All those years dad taught me what he knew and once started work the boss, an old timer, taught me more.
Now after all those years as a mechanic, a mobile home mover, setter, and fixer, another 18 years as a small engine tech, I was forced to retire due to a C4 that disintegrated causing some nerve damage.. Ain't much left but to share my knowledge and go out to my playpen (shed) when I feel up to it. I have a lot of projects started and don't know when and if any will get accomplished. 
So if I can help or teach I will --- If I know the subject enough to help.
Have a wonderful Day, and be careful


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