Coil problem?

[John Rizzardi 70]

Hello all and thanks for taking the time to read my post, Thought i saw spark at plug while testing the other day, so i moved on, while plug was out i cleaned it, did not seem bad but why not, i had it out, little bit of fine sandpaper and check of gap and put plug back in, still will not start, turns over but not start, going back over the coil/plug a few days later, and after trying to start it again, pulled plug again and it was just as clean as when i cleaned it, checked plug with ohm meter and plug measured out to be fine (.03) from top to core at bottom, then from top to other end of plug and had (0.0) plug is fine from my test, could throw it in one of the mowers to check for spark, if that test proves plug is ok, do i then go after Coil, could also check coil with meter, again battery is fine 12.91 volts, plug shows signs that it did not fire, clean, no carbon. Ideas and thoughts would be appreciated, and tried. thanks to any member who reads this. 

[Achto 27,597]

8 hours ago, John Rizzardi said:

Ideas and thoughts would be appreciated, and tried. thanks to any member who reads this. 

 

What model tractor are you working on? Does it have battery ignition - (automotive style coil) or magneto ignition (coil that is under the fan shroud)? Does the tractor have points, if so have you cleaned and set the gap on them? Sorry for all the questions, just need more info.

[oldlineman 1,481]

All of what Achto said, plus I would replace plug, not questioning your testing abilities but have seen good looking plugs not fire for whatever reason. Bob

[953 nut 55,284]

Bob and Dan have given you some good places to look, Presuming your ignition system is battery powered do you have 12 volts on the "+" post of the ignition coil with the key in the run position?

 

There are three main types of coils that find their way into the points-based tractors,

 

1. THE CORRECT COIL = this coil has a “internal resistor" within the coil body that restricts the amount of current that flows thru the points and coil combo. The internal primary resistance of this type coil can be measured with a multimeter at about 3 - 4 ohms. If 12 volts powers a 4-ohm resistance, 3 amps flows and that equates to about 36 watts of power - warm but not hot.

 

 

 

 

 

 

 

 

2. INCORRECT COIL - REQUIRES EXTERNAL RESISTOR - this look alike is visually identical to the correct coil but its internal wiring can overheat if an "external resistor" is not used in series with the coil. The primary resistance of this coil will be in the 1 - 2-ohm range. The external resistor accounts for another 2 ohms. Properly configured, this combo is the equivalent of the 4 ohm internal resistor coil discussed above.

 

If this coil is used alone, the electrical system will see the lower resistance and double the current flowing thru the coil and points. The result is over-heating the coil and premature eroding away the point's contacts.

 

12 volts powering a 1.5 ohm circuit equals 8 amps of current flowing and generating nearly 100 watts of heat and energy. We are now seeing the coil get hot.

 

 

 

3. ELECTRONIC IGNITION COILS - these are the high energy bad boys of the ignition world and demand gigantic gulps of current to operate as intended. They will fry points within minutes. The primary resistance of this style coil is usually well under 1 ohm and current draw can be near 20 amps. These coils are fine if you drive them with electronic ignition modules. They will fry GT wiring very quicky. 20 amps of current flowing thru this circuit generates over 200 watts of power. Wires melt, points vaporize.

 

Measure your primary ignition coil resistance. Anything less than 3 ohms and you have either a shorted coil or an incorrect coil on the tractor. A correct coil should be labeled "12 volts" . If you see "external resistor required" on the coil or the coil looks like it came out of a spaceship, you have the wrong coil.

[John Rizzardi 70]

Sorry for not being complete, Tractor is 414-8, Has automotive style coil, do not believe it has points, with not seeing a distributer i do not have points, to be sure, where would i look for distributer ? 

[953 nut 55,284]

Is your engine a Kohler?

[Achto 27,597]

8 minutes ago, John Rizzardi said:

Has automotive style coil, do not believe it has points

 

With an automotive style coil you will have points. They will be under a cover on the engine. In the picture below the points will be under the cover that has the white tape on it. With only one cylinder there is no need for a distributor.

 

Edited December 14, 2022 by Achto

[John Rizzardi 70]

Yes Engine is a Kohler, just checked coil (positive side” for 12 volts with key in “run” position, saw no voltage, well saw 0.003, seems no voltage is there, thanks for reading and responding all

[WHX?? 48,827]

Check to see if there is 12 vdc at the ignition switch.  If there is very possible bad switch. 

[John Rizzardi 70]

[John Rizzardi 70]

These are pics of test on coil i. just last 10 min. seems like coil is good?, am i wrong?

[Achto 27,597]

Coil looks good.

55 minutes ago, John Rizzardi said:

(positive side” for 12 volts with key in “run” position, saw no voltage, well saw 0.003, seems no voltage is there

 

Reinstall the coil and see if you can get battery voltage to it with the key in the run position. It will need 12vdc to the "+" side of the coil. 

[John Rizzardi 70]

Thank you Achto, b4 i removed coil this morning i took the reading you just suggested and i saw 0.003, took that to mean no voltage, with coil being visually confirmed with meter 15 min ago. i’ll put coil back on machine, WHX?? suggested to check for 12 vdc at ignition switch, not to sound stupid here, is ignition switch all one unit, including key? or can i check for voltage without removing component from tractor, sounds dumb i think, just don’t want to do more than i need to, members opinions do count to me and want to follow what i’m told. Thanks again.  

[John Rizzardi 70]

just realized my earlier test on coil was wrong, by accident i checked negative side with key in run position, i’ll put coil back on machine now then check positive side of coil with key in run position, see what i get when testing it the way i was told to🤦‍♂️

[Achto 27,597]

One other thing to check. Make sure your PTO is disengage/off. If it is on the ignition will not fire.

Edited December 14, 2022 by Achto

[953 nut 55,284]

10 minutes ago, Achto said:

Make sure your PTO is disengage/off. It it is on the ignition will not fire.

With an electric PTO the starter will not turn over with the PTO switch on.

[John Rizzardi 70]

Thanks again for advise guys, never engaged ( meaning never used PTO) could i have engaged it electrically by just getting on tractor, have no idea how to turn PTO on! While i’ve got no need at this point for PTO (i bought tractor because it had a Trac-Vac system attached to it), since i don’t know where to turn it on (on instrument panel?) not sure where to check to see if it is on!, Guess i’m asking for more help. Thanks again guys for your input.

P.S.- checking vdc on positive side of coil with key in “run” position (coil is back on machine) still saw no voltage. (0.03 was voltage reading)

[John Rizzardi 70]

So sorry for my earlier comment about PTO location, i was always using it when i engaged or disengaged mower blades !! Mower did stop if i got off tractor with PTO engaged, so the PTO IS currently disengaged and tractor will start but not turn over, thats been the problem for the last week!! Help!! Looked at fuel system, did a big clean out of fuel tank, petcock was fine, replaced fuel filter and all new fuel lines, moved on to electrical end of tractor, and with members help checked coil (seems ok). Really trying to avoid “easter egging “ here , meaning replacing parts till i get the right one, no way to do job correctly (unless your pockets are deep, mine are not!), where do i go, what do members think i should check next?

[pfrederi 17,741]

Start  but not turn over???

 

Does the engine spin when you try it  or nothing happens..silence.

[Achto 27,597]

1 hour ago, John Rizzardi said:

P.S.- checking vdc on positive side of coil with key in “run” position (coil is back on machine) still saw no voltage. (0.03 was voltage reading)

 

You'll need to figure out why power is not getting to the coil. This seems to be the source of your issue.

 

Click on the link below for a wire diagram.

 

[Achto 27,597]

Note you can not test for voltage across the + &. - terminals on the coil. Test from the + terminal to engine or battery ground.

Edited December 15, 2022 by Achto

[Jeff-C175 7,202]

1 hour ago, John Rizzardi said:

more help

 

Check the PTO switch, you should have 12V on both sides with key on.

 

 

Also, even if the PTO switch is BAD, but the SEAT SWITCH is GOOD, you should get 12V to the coil if you are in the seat, so hook up the meter to the coil +, turn the key ON, push the seat interlock switch down and see if you get 12V.

 

 

[John Rizzardi 70]

Thank you guys again for comments, when i’m done at Dr and again back home, i’ll try (and download/print) all the ideas i’ve read here, pretty sure this is not a big problem, snd like i stated earlier, i do not like “easter egging” 

[8ntruck 7,014]

Working from memory here, I'm thinking that the seat safety switch cuts the power to the ignition and the PTO safety switch cuts the power to the starter solenoid, preventing the starter from operating.

 

The points are between the coil and ground, so if you are checking voltage at the coil by measuring across the primary terminals on the coil will read 0 if the points are open.  If the points are closed, you should see a voltage reading.

 

Good luck and have fun.

[Jeff-C175 7,202]

4 hours ago, 8ntruck said:

thinking that the seat safety switch cuts the power to the ignition and the PTO safety switch cuts the power to the starter solenoid

 

Sorta...  the PTO switch is a double pole, one pole inhibits the starter circuit if PTO engaged, and the other pole is in parallel with the seat switch to cut off the ignition.

 

If operator is out of seat and the PTO engaged, ignition is killed.

 

 

So, if the starter cranks the engine, then that 'half' of the PTO switch is OK, but there could still be an issue with the other 'half' (pole).

 

.

 

 

Edited December 14, 2022 by Jeff-C175