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Discussion Starter #1
I am at a point where I do not know what else to try. I bought my 1978 John Deere 214 a year ago and immediately replaced the carburetor, points, and condenser. As well as put fresh oil in it, fuel filter, fresh gas, air filter, and spark plug. It was running pretty good for a while. Now, it is backfiring or missing at 3/4 throttle and full throttle. Sometimes it doesn't have the power to mow and surges and struggles to do so. I have tried tuning the carburetor countless times and it does not help at all. It idles perfectly and starts up without a problem every time. So I just replaced the coil, thinking that could be it. Didn't help at all. Valves are in spec. Today I bought Marvel Mystery oil, put some in the gas, put some in the crankcase, and continuously sprayed it in the carburetor while running. It has the power to mow now but still backfires constantly. I have no clue what else to try and it's quite frustrating. I've read through every forum related to this that I can, and there is lots of helpful info that I have tried, but nothing has resolved my problem yet. I have also watched the choke while it is running, there is nothing wrong there. Compression looks good at 140psi.
Does anyone have any ideas? I have heard that these k series are notorious for sticking exhaust valve, I was hoping the Mystery oil world help with that. I ran it for at least 25 minutes and spent some time mowing as well. Any advice is appreciated!
 

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Cylinder head may also need to be decarboned. Will require head removal. Would also allow you to inspect valves.
 

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Discussion Starter #4
Maybe I should add that I replaced the carb with a cheap $20 one. I am beginning to think that it may be the problem. When tuning the carb I make entire full turns of the high-speed screw without hearing barely any change in how the tractor runs. I plan on rebuilding the original carb tomorrow to see. I cant remember if I took it off because it was faulty or because I felt good about a new carb being so cheap.
 

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Discussion Starter #5
I have never tried seafoam but another buddy recommended the same. I will have to give it a try. Was hoping the marvel mystery oil would be about the same thing but maybe not.
 

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Not the same, but both are good. Do both, clean/try old carb and then the Seafoam...do the Seafoam outside, messy business.
 

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You said you put new points and condenser in a year ago. I think it would be worth your time to check the points. Is the gap still set to 0.020"?
Make sure they are clean (no oil) and not pitted. The points and condensers usually last a long time, but condensers supplied now-a-days are of questionable quality. Also check that the points push rod moves freely in it's bore.
Check the wiring from switch to coil and coil to points for fraying or loose terminals.
If no problems found, go back to the carb. Maybe try another one from a different supplier. From what I have read here, the off shore knock offs are hit and miss, but mostly good.
I would gamble on one of those if I needed one today. Getting parts for the original Carter/Kohler models is getting harder and more expensive.
Keep us posted of your progress.

tommyhawk
 

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Discussion Starter #8
You said you put new points and condenser in a year ago. I think it would be worth your time to check the points. Is the gap still set to 0.020"?
Make sure they are clean (no oil) and not pitted. The points and condensers usually last a long time, but condensers supplied now-a-days are of questionable quality. Also check that the points push rod moves freely in it's bore.
Check the wiring from switch to coil and coil to points for fraying or loose terminals.
If no problems found, go back to the carb. Maybe try another one from a different supplier. From what I have read here, the off shore knock offs are hit and miss, but mostly good.
I would gamble on one of those if I needed one today. Getting parts for the original Carter/Kohler models is getting harder and more expensive.
Keep us posted of your progress.

tommyhawk
I appreciate the response. Yesterday, I did check point and they were still gapped correctly. To be sure it wasnt points/condenser, I swapped them out with the ones I replaced. I only replaced them last year to have a fresh slate. Changing them back to the old ones did not make a difference. Im going to mess with the old carb today and keep this thread updated.
 

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Your backfiring could be ignition related.

Things to check:

  1. Make sure condenser is properly grounded.
  2. Start engine at night and open the hood and look for sparks jumping off the plug wire to the frame or a ground. Especially to the throttle or choke cable. If the spark plug wire has cracks in the insulation you may be loosing sparkies to ground! This is hard to see in the day.
  3. Try a new plug and gap it properly to .035 in.
Hec
 

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Discussion Starter #10
Your backfiring could be ignition related.

Things to check:

  1. Make sure condenser is properly grounded.
  2. Start engine at night and open the hood and look for sparks jumping off the plug wire to the frame or a ground. Especially to the throttle or choke cable. If the spark plug wire has cracks in the insulation you may be loosing sparkies to ground! This is hard to see in the day.
  3. Try a new plug and gap it properly to .035 in.
Hec
Plus is new and gapped properly. You raise an interesting point though, Maybe I have wire wrong... my condensor had just a single wire and I have it connected to the positive side of my coil.. is that wrong?
 

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Discussion Starter #11
Plus is new and gapped properly. You raise an interesting point though, Maybe I have wire wrong... my condensor had just a single wire and I have it connected to the positive side of my coil.. is that wrong?
Well I guess I should add, there is a ground attached to the bolt where the coil is mounted... electrical is my weak point for sure.
 

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Condenser goes on coil negative.
 

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The condenser wire goes to the negative terminal on the coil.

Here is an electrical schematic to help you.

Hec
265242
 

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Discussion Starter #14
The condenser wire goes to the negative terminal on the coil.

Here is an electrical schematic to help you.

Hec
View attachment 265242
Thanks Hec, I did just realize this. Just switched both points wire and condenser wire to negative side, and ignition switch wire to positive. Had it backwards. Didnt change a thing unfortunately, running just as bad.
With the old carb I put on today, it will run on half and full throttle, still with the same backfiring. But it does not want to idle with this carb. Might problem may be with the carb but not sure.
 

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I would reinstall your old condenser if you still have it. I don't know if connecting it to positive side of the coil could of damaged it. It's worth a try. Now you know how it's installed!

Hec
 

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Discussion Starter #17
If it backfires through the carb, go into the carb...through the exhaust go into the engine.
Just ordered another new carb so will try that early next week when it gets here to try and rule out carb. Really want to avoid tearing the engine apart if I can.

I do want to re-mention on this thread that the previous owner switched this tractor from mechanical fuel pump to electronic fuel pump. It is adjustable, but even on the lower settings it keeps the fuel filter completely full... I wonder if the fuel pump could be causing flooding or extra gas to be pushed through the carb but I dont really think that makes much sense to be honest.
 

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If it does end up being the electric fuel pump you could do like I have done on one of my tractors. I have a electric fuel pump on a 212 that was pushing too much fuel to the carb, so I installed two tee's and a one way valve I acquired somewhere. I installed one tee before the fuel pump and the other next to the inlet on the carb. Now the fuel comes from the tank line, through the first tee, into the fuel pump, goes up to the second tee, which splits the fuel. One side feeds the carb, the other passes through the one way valve and goes back down to the first tee. This way any excess fuel the carb doesn't use gets sent back to the inlet side of the fuel pump, making a fuel "loop".
 

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Discussion Starter #19
If it does end up being the electric fuel pump you could do like I have done on one of my tractors. I have a electric fuel pump on a 212 that was pushing too much fuel to the carb, so I installed two tee's and a one way valve I acquired somewhere. I installed one tee before the fuel pump and the other next to the inlet on the carb. Now the fuel comes from the tank line, through the first tee, into the fuel pump, goes up to the second tee, which splits the fuel. One side feeds the carb, the other passes through the one way valve and goes back down to the first tee. This way any excess fuel the carb doesn't use gets sent back to the inlet side of the fuel pump, making a fuel "loop".
Very interesting. So Im not ridiculous for thinking my fuel pump may be pushing too much fuel? You already had this problem yourself?
 

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In my case the fuel pump I had was supplying too much fuel, I could see it running out of the carb when I turned the key to the run position.
 
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