420 crawler quitting and problems with high idle

[justjd420]

I have a 420 Crawler believed to be a '57. The crawler has been family owned since new and has been used throughout year during summer on upstate New York vegetable farm and plowing snow with original attached blade. I have recently experienced the crawler cutting out during operation and hard starting that was caused by worn original ignition switch that was replaced. After replacing the switch with original JD part the operation seemed flawless except for a slight skipping while running. I replaced the points and condensor along with original plug wires and plugs. The skipping then was corrceted and the crawler ran great. The problem that now arose is the fuse is blowing during operation and sometimes when the ignition switch is turned on before starting. Also I have recently experienced the crawler cutting out during operation as if it was running out of fuel. The first time this happened to me I believed it was running out of fuel while plowing snow so I parked it before it had a chance to fully quit. I used it about week later for snowplowing and filled with fuel before use thinking it was low on fuel. The crawler started right up with no problems and after using for about 30 minutes the crawler again acted as if it was running out of fuel and stalled out. I was not able to start the crawler after several attempts of turning starter over. The points were checked for spark and there was none present. Fuse was checked and was fine. I let sit for a day outside and attempted to start again with no luck cleaning screen to sediment bowl and checking to see if carb was getting fuel. The carb float bowl drain allowed alot of gas to flow out and the line leading to carb also seemed clear. After letting sit for two days in winter conditions and several failed attempts I just tried one more time before towing and the crawler started right up as if there was no problem so I parked inside immediatley lol. What is going on with the girl? Also the idle seems not to kick down and races real high all of a sudden within same time after changing points. Is there suppose to be a sring on idle arm for govenor to bring idle back down? I can bring back idle to low manually by placing pressure on arm behind carb but it kicks back up once I take the pressure off the arm. I'm very thankful for your site because I'm a third generation owner and plan on keeping this girl running for fourth generation. Thanks, Joe

[JD440ICD2006]

The timing is critical on these. Get the service manual and set the timing per that book. The timing can make them slow to idle down, or not even idle down. The timing can also cause them to run hotter than they are designed to run. (if you do not own the service manual, order one and let us know. Someone on here can walk you through how to time it properly.)
Have you replaced the coil? It could be breaking down from heat once the engine warms up.
Check all wiring and make sure you do not have a wire rubbing and shorting things out.

[Lu47Dan]

The shutting down and not restarting sounds as if you have a wire going to ground in the ignition system , first wire I would check is the wire between the coil and the distributor . Check for cracked insulation and for worn spots , if the wire appears good check it with a multimeter for an open circuit . Check both the coil and the points for power . When checking the wire for an open circuit move the wire around and see if it has break in it . And old analog meter (needle style) is the best for this test as it shows breaks a digital just blinks at you . Also with the ignition off disconnect the positive terminal from the battery , use your meter to connect the post on the battery and the terminal clamp , if you get a reading you have a current draw somewhere in the system . I check my equipment for this once a year .
The Fuse blowing out sounds more like a dead intermittent short or a highly corroded termination . Also check your grounds as they can cause a lot of mischief Take them off and clean them and the surface they mount to . I have not had my crawler long but I have worked on a lot of "Old Iron" and have seen a lot of problems in the electrical systems on them . Wires get old and brittle , resistance builds over time to make wires hot and reduce voltage and amperage carry capabilities of the wires .
Hope this helps . Dan

[justjd420]

Thanks for the suggestions guys. Just a couple more questions for follow up. If the coil was bad as heat will break it down than why did it take two days of sitting in the cold winter climate to make it work again? Should it have started when coil cooled down?? I believe the timing was right on when I replaced, at the same time, points, condensor, plugs and plug wires. Why would the timing have to be set again?? Do you know if the idle arm behing the carb should have a spring on it to kick idle back down?? It appears that the arm with hook like figure attached to carb next to govenor rod is loose and may be fashioned for some type of spring. Have owners manual but it doesn't show this area with picture. Any help is greatly appreciated. Thanks.

[JD440ICD2006]

I had to learn the hard way but I will not be without the parts and service manuals for any old iron that I am keeping alive.
The complete parts breakdown of the throttle linkage would show you if anything is missing and/or broken.
Anytime I put in new points, I re time the engine.
It seems that what you are experiencing is a combination of breakdowns in wiring, coil, and possibly a timing issue.
The answer could be that it is a faulty wire causing all of it, I threw the coil issue in there as it is a candidate when you are having ignition issues.
I suspect now that you may be missing a part on the throttle linkage.
Let us know what it is and how you fix it.

[Tractor 850]

I had an intermittent electrical problem with one of my tractors.
I thought it was a bad ground, as it was doing crazy things, but it turned out to be a bad amp meter.
On this tractor all current except the starter and starter solenoid ran through the amp meter.
Check you amp meter with a multimeter.
There should be almost no resistance.
If you don't have a multimeter move both wires on the amp meter to the same post, bypassing the meter.
If the problem goes away, replace the meter.
I went nuts with this, replacing almost everything when all I needed was an $8.00 replacement amp meter.

[Lu47Dan]

Hmmmm , If you are talking about the arm that is attached to the throttle shaft , it should not be loose on the shaft . When I bought my crawler the arm was completely off the throttle shaft , years of use and probably abuse had deformed the end of the brass shaft to the point that the arm fell off . I purchased a carburetor kit and it had a new shaft assembly . I rebuilt the carburetor and hooked up the governor linkage and it works like new again . The arm has no provision for a spring to be hooked to it . Take a mechanics mirror and look at the throttle shaft where the arm attaches and see if the connection is loose if it is rebuild the carb and replace the shaft . One thing check the governor rod hole for burrs before installing it it will save you some aggravation .
I have had coils that one day would start an engine and the next would not . But before replacing the coil I would chase down the electrical system for shorts and bad wires . Dan

[Stan Disbrow]

Hi,

The running OK and then leaning out sounds like the filter screen behind the fuel input fitting at the carb is half clogged.

As you push, the thing burns more fuel, of course. If the screen is partially clogged, then it slowly drops the fuel height in the bowl, leading to a lean condition. As in it acts like it's running out of gas. If you stop the machine for a few minutes, it'll be fine again as the fuel fills the bowl back up.

This can also manifest itself as being OK with a full tank of gas, yet coming into play at a half tank or lower. This is a gravity feed system, so the fuel pressure is higher when the tank is full, allowing enough gas to get into the bowl past the partial clog.....

You have to pull the fuel line off the fitting on the carb and then remove the fitting itself. There's a small tubular screen that's part of the fitting that lives *inside* the carb body. It clogs easily and it seems no one knows it's there so it never gets cleaned out.....

Later!

Stan

[Lu47Dan]

Stan , When I did the rebuild on mine the little screen you pointed out was not there . So I was unaware of it .
As for the pressure on the gravity feed system , it would be about 0.8 to 1 psi (maximum) water column of pressure so gasoline being lighter than water you would have less actual pressure at the screen
Pressure in a column of water is 0.433501 psi per foot of height , diameter of the column does not matter . As I am not going out to get measurements in this nasty weather we are having today . I figured one to two feet above carburetor inlet for the figures I quoted .
I can see why the flow would get restricted by a dirty screen . Dan

[RANDY Fay]

Just a thought I would pull nozzel out of bottom half of carb ( under adj.screw) clean pin size holes --I use tourch tip cleaners or wire off parts tag--be sure they are all open--this is where I find the most trouble with these little marvel-schebler have fun Randy

[justjd420]

Thanks to all who have provide such great insight to my problem. I will be applying suggestions starting with fuel and working towards electrical if not cured. I will say that the screen you talking about hasn't been removed for cleaning in at least as long as i can remember. I will report back soon.
Joe

[Gil]

We may be helping you solve multiple problems. When I read your initial post again, you said that when the crawler stop you checked the points and you were not getting spark. STOP there. You have to fix this problem first. I think JD440ICD2006 and Lu47Dan had you on the right track. I will try to add to their good advice with some specific steps.

Most of the wiring you see running around behind the dash is for the charging system, lights, etc. As far as the ignition system goes there are just two wires. The first is the battery ground wire. Don’t just wiggle it. Take it off and wire brush the cable ends and make sure it has unpainted contact directly to the frame. The terminal ends must be sturdy. If the battery end has one of those cheap bolt on terminals, remove it and wire brush the cable wire strands and the terminal. Corrosion here and on the battery terminals are a prime cause of gremlins, yet they usually look good and tight. Be sure you are using a SIX volt battery with POSITIVE ground (I assume it is like a JD440), not like the twelve volt negative ground systems we have today.

The second wire in the ignition system goes from the negative side of the battery, through the amp meter, then through the switch, then through the coil, then through the points, and on to the spark plugs. This wire may begin directly at the negative terminal of the battery or it may come from the starter where the negative battery terminal is connected with a big cable. To find your fault, I am going to suggest that you by pass a lot of potential problems with the amp meter, switch, and wiring harness by running an additional wire from the negative side of the battery and going directly to the coil. Remove the coil wire that now comes from the switch. Insulate its end with electrical tape. Connect the new jumper wire to the coil. Connecting this wire is the same as turning on the ignition switch. You do not want to leave this wire connected while you go inside for lunch, because it would be the same as leaving the key on, and current would be running through the points.

With this jumper wire on, test the points and see if you have spark. Just put a screw driver blade in the points and manually open and close them. If you do have spark, the problem is in some of the wiring that you bypassed. If the engine starts you can go out and use the crawler this way. See if it still has problems when it gets hot and under load. Just disconnect the wire when you get back. I carry a piece of wire in my tool box that is just this length and about 14 gauge with alligator clips on both ends. It has gotten me back to the barn a number of times.

If you still do not get spark the next suspect is the coil. Coils are mysterious little black boxes that you cannot look inside of. If you have electrical problems you never know if they work or not. Good news is coils are cheap and since you are going to keep the crawler, they a good investment to have around. I recommend you order one. Put it on and see if this solves the problem. If it does not, REMOVE IT and put it back in the barn to keep for the next time you are trouble shooting.

If the problem is not the coil it must be in the wire going to the distributor or a short in the distributor itself. Check the wire ends and look for cracked insulation or just replace it with a new wire. The most important point is to look at the insulation where it goes through the distributor cover. It may look fine but is still failing. Also see if the wires or points are touching the distributor wall. Another problem may be under the point’s plate, especially if there is moisture under there. If you are getting power to a good coil and the points are not arcing, the problem is in there somewhere. If you get the crawler running and it dies in the field, immediately check the points.

Once you get the points sparking you can worry about timing, carburetor, wiring harness, plugs and such.