Farmall 140 ignition problem

[cachip12229]

I am working on an International 140 tractor and have an ignition issue. I have no spark at the plugs. I have power up to the distributor and to the points, but not past that. There is no spark at the points when I crank it. When the points are open, I have 12v of both sides of the point contact. The points and condenser are both brand new, as is the cap and rotor. I can't this this tractor to fire up. What am I missing?

 

[560Dennis]

Welcome to a new user .
12 volts at points ,I think this is way to much , should be 5 to 6 volts. Points are oxidized( burnt to high resistance level the points contact to permit). So what other modifications are there?
Need to measure the reading at points cranking engine. Get back to us for discussion if so please.

 

[m16ty]

Welcome to a new user .
12 volts at points ,I think this is way to much , should be 5 to 6 volts. Points are oxidized( burnt to high resistance level the points contact to permit). So what other modifications are there?
Need to measure the reading at points cranking engine. Get back to us for discussion if so please.

Even if you have a resistor, you will usually have 12v (on a 12v system) at the points when checking with a volt meter. The resistor has to have a load on it for it to drop the voltage.

 

[m16ty]

You shouldn’t have voltage on the stationary side of the points, it should be grounded to the distributor body.

Without looking at it, I don’t know what your problem is. It should be noted though, with the new parts you get these days, it’s pretty common to buy new ignition parts and they be bad right out of the box.

 

[used red MN]

When the points are open, I have 12v of both sides of the point contact.

Hello cachip12229, welcome to YT! I’m short on time this morning so I’ll try to make this short. Spark is not found at the contact of the points. Rather an arc occurs as the points are opened and the circuit is broken. As said by m16 both sides of the points showing power is not right. If this is a newly painted engine a distributor there is a possibility that the distributor is not grounding properly. When the points close you should see nearly zero volts on the lead from the distributor at its terminal on the coil. New points can have a thin protective coating on them try wiping a piece of card stock through them a strip of a cereal box etc will work if it is ran through both directions so the bare side slides over each contact surface. Get the points to “ground” the circuit when closed, if you have a test light I like to use that. When you have it testing the coil lead terminal from the distributor and it flashing on/off rapidly when cranking you will be 90 percent on your way to a working sparking ignition.

 

[560Dennis]

You have positive or negative ground on your battery ?

 

[Jimmydog]

Dennis brings up a good point. sounds like it's been modified from OEM. Early versions were 6VDC pos. grd. later versions were 12VDC neg. grd. If it has an alternator instead of a generator it's been tampered with. Good chance not in a good way. For example my IH 460 has been converted to alternator and while poking around under the dash I came across a live unfused bare ended wire just hanging there. I shudder to think what could have happened if it grounded. Still haven't figured out where it's getting energized from.

Did this machine run before you got your hands on it? Assuming there isn't a cross connected wire some where else; check to see if the wire that goes from the coil to the points is chaffed and shorting out where it goes through the distributor base. Should have a rubber gromet there, but they rot away after a while allowing the wire to wear thru. The other thing is to check the high tension wire to the center of the cap. Check for continuity. I had one were the wire was replaced with a carbon fibre core, it was visibly burnt thru between the core and the metal clip. I fixed it only to have it burn out shortly again. Those tractors should have copper cored wires. Anyway, no matter what, you should not have voltage at both point contacts. As mentioned one side goes to ground. Whatever that is (MUST be negative for alternator). Good luck and let us know how it turns out.

 

[cachip12229]

Sorry I haven't gotten back soon, but life got in the way. To answer some of the questions asked. It has ben converted to 12v several years prior to me coming in contact with it. It is now a negative ground. The tractor did run about a year ago when it was last parked. The last user told me that it felt as though it lost power, so he pulled it in the shed and parked it, and there it sat until I was asked to look at it. The points, cap, rotor and condenser have been replaced. I am aware that sometimes new ignition products are faulty and I am checking with you all in case I'm missing something obvious, before I start replacing new parts. I've used my muti-meter as well as a test light and there is power on both sides of the points (continuity), which I'm sure is not suppose to be that way. One thing I want to add, with the ignition "on", the coil gets super hot, to the point you can't hold it without a glove. I switched coils and the results didn't change. My old-time tractor mechanic was the one whjo suggested a ceramic resistor to fix that problem.

I appreciate the input... this has been frustrating to say the least. The current operator isn't a tractor guy. All he knows how to do is drive it. His father-in-law is the owner and he is a long time farmer. He's got some serious health problems but would like to see the tractor up and going again before he's no longer with us.

 

[Jim.ME]

You describe conflicting issues. Coil getting hot quickly sounds like points are closed and allowing power to flow to ground. Check to see that the wire for the distributor or the condenser lead have not grounded out.

Power on both sides of the points sounds like the distributor is not grounding. The coil would not be hot as no power would be flowing. It is not a positive negative ground issue.

 

[Dennis K (WA)]

I would look closely where the small coil wire comes to the distributor and where the points and condenser connect to the stud there. Sounds like it may be grounding to the housing at that point. If constantly grounding out I think the coil would over heat. Good luck
Dennis

 

[BarnyardEngineering]

The owner has probably been running the tractor with no ballast resistor and a 6V coil. That's fine and dandy for a while but eventually you burn the points or the coil. That's what the ballast resistor is for.

Coil is getting hot means that it is getting power and charging. You've got a dead short to ground if it is getting hot and you have a no spark condition.

Disconnect the small wire from the distributor, disconnect the coil wire from the distributor cap and hold it close to the engine block like you're testing for spark. Turn the ignition switch on, and then briefly touch the small wire from the distributor to ground, then remove it. You should get a spark from the coil wire. You are performing the function of the points in this test. IF you get a spark that means the points are not breaking contact and allowing the coil to discharge a spark to the distributor cap. That points to bad points, or a short where the terminal goes through the side of the distributor.

 

[Jimmydog]

Points and condenser have been replaced" there's your clue. Something shorted/not installed properly I'm guessing. Like Dennis mentioned check that small wire to see that it's not chaffed and touching metal base of distributer. Yeah, that coils is dead shorted. I like Barnyard's diagnostic.

 

[used red MN]

I've used my muti-meter as well as a test light and there is power on both sides of the points (continuity), which I'm sure is not suppose to be that way.

You describe conflicting issues. Coil getting hot quickly sounds like points are closed and allowing power to flow to ground. Check to see that the wire for the distributor or the condenser lead have not grounded out.

Power on both sides of the points sounds like the distributor is not grounding. The coil would not be hot as no power would be flowing. It is not a positive negative ground issue.

I think we need to make sure that both you understand what your meter is telling you and that it is being conveyed to us correctly. You have continuity in parentheses this bares some more details. My guess is you are simply reporting this incorrectly. The black or negative meter lead should be connected to a good ground on the engine the red or positive meter lead is your probe for testing and the meter set to a DC voltage scale to cover the 12 volt range. To have power/voltage showing on the contact side of the points that is screwed into the points mounting plate in the distributor would mean the distributor plate or the housing itself is not grounding or making proper contact to the engine. That non moving side of the points set should always be grounded and show no voltage potential or power between it and the engine ground.
Others have given you some tips on testing portions of the system disconnected which is fine. When you get things back together in my opinion the final test should be as stated at the end of my reply 5. ..if you have a test light I like to use that. When you have it testing the coil lead terminal from the distributor and it is flashing on/off rapidly when cranking you will be 90 percent on your way to a spark producing working ignition system.

 

[cachip12229]

I'll do that today. Thanks.

 

[cachip12229]

Thanks again for all the input. It helped in locating and correcting the problem, which wound up being a a shorted main distributor post. Electrical problem solved and I have power all the way to the plugs. Machine still won't start but I know it has fire.

 

[504]

But you are doing the troubleshooting the correct way. Fix one thing and then look for the next problem. Guys spend a lot of time and money fixing things that aren’t broken. ( no fire will not be fixed by rebuilding the carburetor)