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John Deere 720 LP troubles

M

Mcneiltc720

New User
My 720 is only running on one cylinder. I have checked the valves and they are fine. I have also checked for fire to that plug and it is there. Anyone have any suggestions?
 
Sometimes a plug will fire in the open atmosphere that won't fire
under compression. Have you tried really opening up the gap for
checking spark? See if it will jump a blue spark over a 3/16 gap.
 
(quoted from post at 03:39:32 12/21/16)
Welcome to YT
Have tried installing a new or different spark plug? Have tested compression on faulty cylinder?
Click to expand...

Yes I have tried a new plug and yes have tested compression. Thank you for the help
 
(quoted from post at 07:38:46 12/21/16) Are you sure you are working on the correct cylinder?
Click to expand...

While the tractor was running I unplugged the right side and it tried to go dead. I unplugged the left side and there was no change so I assume that it is the left side. Which I am guessing is the number 1 cylinder.
 
Did you just buy this tractor with this problem or have you had it and this problem just showed up ? Did it show up right after changing the dist. cap ? If so you may have the wrong cap on it. Guy brought me a 520 lp with a Dubuque cap on it. The terminals don't match up and it will run on 1 cyl. I was lucky I figured it out as soon as I did but that was a head scratcher for awhile.
 
(quoted from post at 08:50:46 12/21/16) Did you just buy this tractor with this problem or have you had it and this problem just showed up ? Did it show up right after changing the dist. cap ? If so you may have the wrong cap on it. Guy brought me a 520 lp with a Dubuque cap on it. The terminals don't match up and it will run on 1 cyl. I was lucky I figured it out as soon as I did but that was a head scratcher for awhile.
Click to expand...

I bought the tractor with this problem. I had someone tell me I need to change the distributed cap. I am also thinking about going to an electronic ignition. Anyone done this?
 
(quoted from post at 11:43:05 12/21/16) What do you have the plug gaped at on lp
they need to be at .012 to. 015
Click to expand...

I figured out my problem. My distributor shaft is worn and it has a slight wobble which is causing the points to not open and close as they should. Ordering an electronic ignition which should fix the problem. Thanks for all of the help.
 
Your old cap if correct ? could just have a carbon track and if so will need replaced.

I'd put a new bushing in the dist. I'd also stay with points if it were me.
I can't help but think a loose shaft can't be good for electronic ign. either.
 
(quoted from post at 12:32:59 12/21/16) Your old cap if correct ? could just have a carbon track and if so will need replaced.

I'd put a new bushing in the dist. I'd also stay with points if it were me.
I can't help but think a loose shaft can't be good for electronic ign. either.
Click to expand...

So I installed the new ignition. The tractor is running much better but still only hitting on the clutch side cylinder. Both plugs have plenty of blue spark. Could there be a fuel problem on the left cylinder and if so what can I do? I just don't see a jet on a propane tractor stopping up.
 
I would get the wobble out of the dist. it can still cause a problem.
The only way can think of fuel problem to one cylinder would be a blockage.
 
(quoted from post at 14:20:21 01/02/17) I would get the wobble out of the dist. it can still cause a problem.
The only way can think of fuel problem to one cylinder would be a blockage.
Click to expand...

Distributor shaft did not have wobble. I was just told that it was probably worn but I checked it and it was fine. The points were badly burnt but I installed the new ignition and did away with that. The tractor runs better on that one cylinder than it did before and it cranks easier. I can't imagine how good it will run when it's hitting on both cylinders. Any other ideas?
 
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