Re: john deere 2020 gas no spark

Posted by John T on June 30, 2019 at 16:34:23 from (45.16.200.171):

In Reply to: john deere 2020 gas no spark posted by Yenshu on June 30, 2019 at 15:58:37:

Yep I have a few ideas that may help find the cause of no spark. Hopefully other fine gents will have more ideas

You say new points are they gapped correct and open n close fully ??

Did you try to remove any oil or film or protective coating they may have been shipped with ?? Try that...

Is the Ignition switch and any ballast (if it has one, resistive wire link, onboard switch, discrete stand alone style, original or modified at some time?) in place and all are good and correct so its sending voltage down to the coils input??? Stick a volt meter on the coils input, turn on Ignition AND SEE IF YOURE GETTING VOLTAGE TO THE COIL !!!!!!!!!!!!!!!!!!!!!! If NOT the switch may be bad,,,,,,,,,or its not getting its input voltage,,,,,,,,,,,,,or if it uses any on switch or wire link or discrete type of ballast (still factory original or modified over the years do you know???) it may be bad/open,,,,,,,,,, REGARDLESS HOW WIRED OR IF EVER MODIFIED OR BALLAST OR NO BALLAST YOU HAVE TO GET VOLTAGE DOWN TO THE COIL !!!!!!!!!!

If the switch is bad or has no input voltage or any wiring from switch down to coil or any ballast (if used and/or not been modified) is bad/open so the coil isn't getting any voltage SHE WONT FIRE

Is the new coil the correct voltage??? If it is using any ballast (no way to know sitting here what if anything has been done in the past) the coil would be a 6 volt NOT a 12 volt coil. If it uses a 6 volt coil but your replaced it with a 12 the spark would be weak. Also if you used 12 volts on a 6 volt coil it will overheat and can stop firing and can fry !!!!!!!!!!!!!

IF ITS NONE OF THE ABOVE AND THE CORRECT VOLTAGE COIL IS GETTING CORRECT VOLTAGE PROCEED

I will start with a few preliminary troubleshooting procedures that only require your eyes maybe a 6/12 volt test lamp but if that doesn't help and you need more open the URL link for my In Depth Troubleshooting Procedure..

1) THE VERY FIRST THING YOU GOTTA HAVE is voltage to be present on the coils high supply (NOT to distributor) terminal when you turn the Ignition switch ON. If not she cant ever fire, but in the event the ignition switch or circuit/wire down to the coil or any Ballast Resistor is bad or open, you can HOT WIRE it by jumping a hot ungrounded battery voltage source to the coils high input supply (NOT to distributor) side n see if she runs then???? If she fires hot wired, you could have a bad ignition switch ((That can happen, when Ignition is on, the switches IGN terminal must turn hot)),,,,,,,or an open Ballast (if it has one) or a bad/open wire from switch to coil.

If the switch is good, if you turn the ignition switch on and place a test lamp on the coils high (NOT to distributor) terminal SHE MUST LIGHT UP. If not again, look for an open Ballast Resistor (if it has one, it should read around 1.25 to 2 ohms across its terminals) or bad/open wires from the switches IGN output down to the Ballast (if it has one) and distributor.

2a) When the Ignition switch is turned on, voltage should appear on the coils high input side. That would be 6 volts on a straight 6 volt system or 12 volts on a 12 volt non external ballasted system, or around 6 volts on a 12 volt system that used a 6 volt coil plus an external Ballast Resistor and the coil is good and the points are closed and they and ALL wiring is good.

2b) To insure the coils low voltage primary winding is not bad/open, use an ohmmeter and measure its DC resistance between its lil + and -terminals. If its an open circuit (no continuity) its bad/open and will NOT work. It should measure around 1.25 to 2 ohms or so if its a 6 volt coil and maybe 2.5 to 3.5 if its a 12 volt internally ballasted coil. NOTE CAUTION have all leads and any voltage source DISCONNECTED FROM the coil for this simple primary winding continuity test.

3) Next, place your voltmeter or test lamp over on the coils other low to distributor terminal side, turn her on and crank the engine over.

4) A test lamp there should flash ON (when points are open) and OFF (when points are closed) as the engine is cranked slowly.

5a) If the lamp never comes on there, the coils primary is bad/open,,,,,,,,,,or the points are never opening,,,,,,,,,or theres a shorted/bad condensor (remove its lead to points and see if lamp comes on, if so, bad shorted condensor or its wiring),,,,,,,,or the points wire is shorted,,,,,,,,or the distributors side pass thru stud is grounded (use ohm meter to test that),,,,,,,,,or the points may have a shorted spring.

5b) If the lamp never goes off as engines cranked, the points are not closing or are bad,,,,,,,,or the wire or circuit is missing from the distributor to the points,,,,,or the distributors not well grounded to the tractor.
She cant fire the coil unless its low side is getting a conductive ground return path via closed points and then the circuit is open when the points open.

Be sure the condensor or its wiring is NOT shorted out and see if the lite comes on (when points open) with the condensor disconnected. If removing the condensor makes her spark, replace the condensor.

Now try my Troubleshooting below

John T

• John T's Ignition Troubleshooting

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