IGNITION RESISTOR BURNING UP

Falcon

New User
I recently installed an electronic ignition assembly on my 9N with front mount distributor. I also replaced cap, rotor button, plug wires & plugs at same time. It ran great for a couple of weeks (probably 7 to 8 hours total run time) then the ignition resistor went out, it was extremely hot to the touch. I installed a new one and the tractor cranked up and ran for about 5 minutes, then quit. The new resistor was also extremely hot and when I tested it it showed no resistance. I decided to check the coil and it shows no resistance between top post and spring on bottom. The tractor was converted to 12V before I got it so I don"t know if the coil is 6V or 12V. Shouldn"t there be some resistance between these two points on the coil? If the coil is bad and I need a new one I will probably get the 12V coil for it. If I do install a 12V coil do I still need a resistor in line? I checked behind the dash and did not see any other resistors in the wiring.
 
wow.. this post is a mess.

1, I'd consult twith the maker of your high dollar e-ignition unit and find out what they reccomend.. since doing the wrong thing can burn up that module.
 
What do you mean by "shows no resistance"? Ordinarily, in the electrical/electronics world, such a statement means that the resistance is ZERO Ohms, i.e., a really good heavy copper wire of short length. What does it mean to you?
Both the coil primary & the resistor will be so near to ZERO, that many persons do no recognize what they are reading or the sorry instrument/techniques make it near impossible for them to obtain an accurate measurement. Your EI mfgr. specifies a minimum combined coil + resistor value of 3 Ohms. The resistor can show a red color & ignite a piece of paper when touched, so keep in mind that it is normal for it to be far too hot to touch, unless you enjoy pain & the smell of burning flesh.
 
I have a quality digital ohm meter. When I said zero resistance I meant the same as touching the two leads of the meter together. 0 ohms.
 
(quoted from post at 12:03:59 06/24/13) I have a quality digital ohm meter. When I said zero resistance I meant the same as touching the two leads of the meter together. 0 ohms.
ot the way it should be. The coils are generally around 0.5 to 1.5 Ohms if 6v and about 2.5 Ohms if 12v.
The standard Ford 12250 resistor is ~0.4 Ohm cold and ~1.7 Ohms when red hot.
 
Thanks for the info. I assume then that my coil is bad if it is reading 0.00 ohms. I guess I will be replacing with a 12V coil. Do I still need any type of resistor with a 12V coil?
 
(quoted from post at 12:45:42 06/24/13) Thanks for the info. I assume then that my coil is bad if it is reading 0.00 ohms. I guess I will be replacing with a 12V coil. Do I still need any type of resistor with a 12V coil?
es. Remember I said that Pertronix specifies 3 Ohm minimum for coil + resistor combination? Well, 3 - 2.5 = 0.5, so......use the Ford 12250 resistor.
 
(quoted from post at 13:29:22 06/24/13) Thanks for your help Jmor, I just ordered the 2 parts. I'll let you know how it works out.
ppreciate feedback. Might try Ohmmeter on the new parts when they arrive, too.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top