no Spark to Plugs

[Anonymous-0]

Hello again,Well my Starter issue has been taken care of,Thanks to Jeff!
I recently drove my TEA-20 about 4 miles down the road to pick up a Snowblower I purchased for the Tractor.When I got to where I was going I pulled off the side of the Road and she quit.
I've checked everthing.I have plenty of Spark going into the Distributor,but nothing coming out to the Spark Plugs. I've replaced the Coil and Condenser.The Points are firing great with nice blue ark. The inside of the Dist. Cap looks good,The Rotor looks good. I have noticed that the Coil is getting real hot when I put ignition to it. I even repaired the broken Springs on the automatic advance.The Plug wires seem to be alright,as so the Coil Wire. I also brought number 1 cylinder to top and the Rotor is pointing to number one terminal on the Dist. Cap. Anybody know what could be wrong?

 

[Anonymous-0]

Squirt some fuel into the intake and see if it fires.

 

[Mathias NY]

Just throwing ideas out... Have you checked the point gap in the distributor? Have you checked the gap on the spark plugs? Are you sure the spark plugs are engaged correctly on the plug wires? Are the wires pushed into the distributor cap completely (had that problem with my tractor last week)? Are the rotor contacts and the inside of the distributor clean?

Hope some of these help you track the problem down. Good luck.

 

[Bob M]

You mention 2 clues: A "nice blue spark" the points and the coil becoming very hot. Both indicate excessive current flowing to the coil. This will quickly burn the points. Also it will overheat/ruin the coil if run like this for very long - hence no spark at the plugs. (A normally working system will show a pale yellow, barely visible spark at the points, and the coil will not warm up noticably.)

Sounds like maybe your TEA-20 has been converted to 12 volts? If so and if the old 6 volt coil was retained, you need to insert a ballast resistor in series with the coil to drop the voltage to 6 volts at the coil. Also you probably need to replace the coil and points with new. (Suspecte the existing coil has failed due to overheating; most likely the points are damaged too).

 

[Anonymous-0]

Are you sure the negative side of the coil is connected to the distributor.It's my guess that you will have current to the points but the magnetic field in the coil is not being excited.
If that is ok then check the carbon is in contact with the rotor button.If all that fails I will buy it.no, post your problem on the HARRY FERGUSON site.

 

[souNdguy]

The coil will -work- in either polarity.. it will work BETTER in the correct polarity.

Please don't make up stuff and guess about electronics.. it only serves to confuse other people..

soundguy

 

[RAB]

Jim,

As I read your post, it appears there is absolutely nothing wrong with your ignition spark, production-wise. The problem is in the distribution to the plugs - ie the distributor.

I am presuming you had a fat blue spark when it actually quit? You are referring to the high tension spark? The one from the coil centre plug-lead type wire. That means your points etc and coil are OK. If you did not check for spark when it actually quit there could be these other issues, but if there was a high tension spark it must be one of these two components - cap or rotor.

There may be an issue with ballast resistor etc but if the spark was there, up to the distributor cap, they are a side issue.

If you are referring to low tension electricity as 'spark to the distributor', disregard the above and start checking from the basics.

So, IF you have a good high tension spark going into the distributor it must be getting 'lost' in the distributor cap or rotor. There are no other parts in this section, unless all the spark plug leads and plugs have failed all at the same time!!

While I can understand that some posters are not real good at describing the symptoms and exactly how/when things were checked, we can only comment/reply on the information you have given. It is a shame that some replies are laying red herrings along the way, so if you think your initial post was not accurate, update it with more information. We want you to find the fault and fix it.

I would initially go with a shorting rotor as my first guess as you are likely to see tracking lines or cracks in the distributor cap.

Regards, RAB

 

[Anonymous-0]

Thanks for all your inputs!
I went back to the Tractor this evening and checked all the obvious things that may go wrong with a Points system again and the only conclusion I can come to is a bad Dist. Cap and Rotor,though they both look fine.But that's the only thing I can figure is wrong. I thought maybe the stud that goes through the side of Dist. for the lead from the coil may be grounding out so I put a new insulator in there.But still no fire at Plugs.The Plug wires are almost new and Spark Plugs look good. I've also checked to see if it may have jumped timing and doesn't appear to have.
So I've ordered new Cap and Points and Condenser and Rotor through Yesterdays Tractors. Hopefully these will get er' back running.
I'll let you all know how I make out. Thanks very much! Jim

 

[Anonymous-0]

Carbon fouled spark plugs will not fire the fuel charge.Take a plug out and see if the spark is jumping across the gap and not running up the insulator nose.Running on the road may have carboned up the insulators.Prolonged idling can foul plugs.Spark plug heat ranges have been moved up a step with the gas we use now.I keep a pair of spark plugs in a covered jar of lacquer thinner for my John Deere.The 2 cylinder tractors will foul plugs fast under light loads.The ohv Ford engine can do it too.Make sure your tractor has a thermostat and is not running too rich.My 640 does not burn oil but if I let it idle while loading fire wood or hitching up an impliment it will skip a bit.

 

[Anonymous-0]

If the polarity is reversed, that is the secondary circuit has a negative ground, a higher voltage is required to cause a spark at the gap. This because the centre electrode is considerably hotter than the ground electrode. The coolant in the water jacket of the block carries away more heat from the ground electrode than from the centre electrode.
Electrons flow much easier from a hot surface to a cold surface than from a cold surface to a hot one.It is easier and requires less voltage for the centre electrode to give off electrons, or negatively charged particles because electrons more readily leave a heated surface.Also, the cooler ground electrode offers less resistance to current flow.
If secondary polarity is incorrect, 20 to 40 percent more voltage is required to complete the secondary ignition circuit. Experiments have proven that 14 percent more voltage is required to ignite a fuel-air mixture when the centre electrode is positive instead of negative in polarity. These same experiments show that 30 percent more voltage is required when polarity is reversed with the centre electrode heated. e.g. if an ignition system were capable of producing 18,000 volts,but required 15,000 volts and had polarity reversed,the ignition requirement would be increased by 30 percent. 15,000 volts by 30%=4,500 volts.
Add this 4,500 volts to the required 15,000 volts, and we find we have a voltage requirement of 19,500 volts or 1500 above the capabilities of the ignition system. Accordingly, available voltage from the coil would be insufficient to ignite the fuel-air mixture in the combustion chamber.

Ignition systems.Ford.

 

[souNdguy]

And all that theoretical 'paper' aside.. it's a sad fact that an ignition coil will fire with reversed polarity. Just look at 98% of the front mount fords running negative ground without an elaborate way to swap the coil polarity.

Guess you are saying none of those exist... right?

Back to what I said.

Correct polarity is ideal... reversed polarity is not ideal.. but works.

Again.. quoting the 'book' only will serve to confuse.. besides you are preaching to the quire.. BTDT.. I got my eng. ticket already.

soundguy