JD 4010 Will not run consistently.

[budgie9]

I have been working with a friend on his JD 4010 for many weeks to get this tractor running after it has been sitting for five years.
We have changed so much on the tractor including the plugs, their cables, points, distributor rotor and cap.
Reset the ignition timing changed the coil, the ignition switch,
Striped and cleaned the air filter just in case,
The carb has been checked and cleaned several times. Marvel Schebler SUX20
Fuel pump changed from a new one back to the original and another new one put in it's place.

All setting in accordance with the full service manual.

Compression is within the specification, so is everything else we can or I should say I can check for him.
Electrics have all been checked from top to bottom, not that there is much to check on this tractor.
There is a new starter fitted prior to myself getting involved but that appears not to be a cause of any issue.
Drained the fuel tank burned the fuel in another tractor so fuel is good. Added fresh feul twice and checked for contamination.

Yet, we can get it to run sometimes. but no power. it will sometimes tick over at 650 RPM and then when we try to increase the revs she will die on us. One time we had it running at 1200 rpm, but then it just stopped completely. Having to push it back it the shed as it would not restart.
Plugs are wet and often black, because we can not of course get it to run correctly, so I am not sure if it is flooding or if it is because we can not keep it running long enough to burn the fuel correctly.

Then it will not start no matter how we try, trying to reset the timing, by moving the distributor, altering the points to both the running manual settings of 22 thou or the service manuals 16 thou, and anything around there. It is just stubborn and will not fire at all.

We are at our wits end with this tractor, so any help or ideas will be gratefully excepted and tried. I have personally put in more hours that I would care to think about, but I do not wish to see my friend put a stick of dynamite under it as it is in very good condition for it's age. But today he is loosing his cool with it.

 

[kthompson]

Some odd things that have helped me: you can shoot shots of WD40 into the air intake to get an idea if it is fuel issue. Gas or diesel engine will run on WD 40 like this. If it starts and runs that way then fuel issue. If you have room to try pulling it to start, use a low enough gear not to run into the towing vehicle. You can get much faster turn of the engine which might help it start and for longer than you can with the starter.
Have you checked the gas line for restriction and the choke to be sure the cable is operating it? You don't mention it popping or such when it is running, a good sign.

 

[Roadworthy]

Be sure the air passage between the air filter and intake manifold is clear. Check the float on the carburetor and be sure the needle can move freely to turn off the fuel flow when float is up. Sometimes the needle can hang up allowing way too much fuel to pass through the carburetor.

 

[budgie9]

Thanks guys, Sorry for the delay in getting back to you both. I was preparing for our first outing in the RV after this long winter (in Canada) and covid tie down. Can't wait to move around again.
We have stripped and clean the air system in fact we did that yesterday, completely. making sure there was no restriction in any of the pipework. Checked the float level yet again and made sure we have fuel. We have not tried the WD40 method suggested by Kthompson, But have tried putting fuel directly into the cylinders of course and get it to fire but it dies away after a few minutes. If I can explain. IF we get her to run, then it will run for a few minutes then dies away, if we try to increase power. if it is left at whatever we get it started at it will run, let us say at 650 rpm. But as soon as we try to change the revs she will die off. Then it will not restart No matter what we try. It is as if once started it has had it for the day.
We have checked the gas lines and we do get some popping from the exhaust, whilst trying to get her started, which indicates to us that it wants to fire but fails.- like as if the timing is out, but it is set at 20 degrees and 16 or 22 thou as per manual. UNLESS someone knows better for this ethanol fuel.

 

[rScotty]

Love those old JDs..

It ought to run at that timing. I have no idea if that is an optimal setting, but IMHO it is close enough for any gasoline engine to run up to medium RPM even if the advance is not working. To make sure that you are timing properly on all cylinders, please check one more time that the spark plug leads are in the correct firing order for the distributor rotation.
When you lay a plug on the head and crank it over, how does the spark look? Is it fat and blue or weak and yellow? If fat and blue with an audible "snap" then at that timing with a correct firing order you can look somewhere else for the problem. The ignition system is good enough. .

With the symptoms you describe, I'd have to say that it sounds like carburation. I think you already suspect that.
As you know, a gas engine that won't start doesn't usually wet the plugs as severly as you describe. With plugs that wet and that black it almost has to be the float or the choke. Especially if it begins to smoke black before it dies.
If it were mine, I'd put a brand new needle, seat, float bowl gasket and especially a new float in it. I've seen far too many "heavy floats" that looked good. Remember that the float bowl gasket is usually part of the float setting too. I'd replace all those no matter how good the old ones seem.
If that didn't work I would go blow out and probe the passages one more time after an overnight soak.

I might even take the offending carb to my favorite hot rod shop or carb rebuilder and offer a bribe if he would just put his eyes on it. As you know, all carbs are pretty much the same.
I remember fighting with a Q-jet double pumper for months before I finally found the shell of a tiny fly or wasp or something in one passage. To the eye it just looked like discoloration, but when you gave it more throttle the remains of the bug would fold over due to the higher flow and block off the fuel passage.

On a JD of 4010 vintage I remember one that fooled me for days that I thought was the carb but in fact it was that it had JD's new automatic fuel valve for the gas tank instead of an old style manual fuel tap. That auto gas on/off valve had a diaphram in it that was supposed to respond to carburettor pressure and turn itself on when the tractor was running and then turn the fuel off when it didn't. Instead, what it did was slowly turned itself off so that the tractor would run for 15 seconds and then the float would go dry and it would stop. Wait an hour and it would do it again. But that was a lean-running condition.... not a overly rich, wet one like you have. So trust yourself. You know it's going to be simple when you find it. Wish I was there for the fun.
rScotty

 

[budgie9]

Thanks for your input rScotty. I have gone through that carb so many times myself. I have to admit I am seriously beginning to think it needs throwing away. I would like to change it for a Zenith to be honest with you. As I seem to think we can never get it to run correctly. But at the cost, to try it out and then find we are still in the same situation with it, it seems a lot of $$.
We have tried to find a replacement, for testing with, locally in Canada, that is, but so far no luck. I have also tried to find a service kit with needles and seats for this Marvel Schebler SUX20 and can't find that either. Any knowledge as to where we may find the needles and seats for it. I can find the gaskets sets.
I started this project with my friend last year in the summer, One day a week, and so far I have lost count of the hours we have put in on this tractor. We also are working on a JD 1840 with a weird hydraulic problem and putting new manifold on a 1948 Fordson.
I think it's a little far from Colorado for you, that is if you could get across the border at this time.