Current to coil

GregoryKS

Member
On WD45. What is the current path to the coil and into distributor when the ignition key is turned on and the starter engaged?
 
battery to starter switch, same terminal to ign switch, ignition sw to coil (or ballast resistor if equipped) coil to distributor (coil polarity to distributor matches battery). Starting switch to Starter. Jim
 
The only time it makes a difference if the starter is engaged is if its a 12 volt tractor that uses a 6 volt coil with a series ballast resistor and is equipped with a ballast by pass circuit fed from the starter switch or key switch or a solenoid.

Often the ammeters LOAD (NOT supply terminal to battery via wire to starter switch/solenoid) terminal is what feeds loads like lights and ignition switches BAT input,,,,,,,,,,IGN out terminal on IGN switch to coils input,,,,,,,,,,,,coils output to distributor,,,,,,,,,,to ignition points,,,,,,,,,,to ground when points are closed. If points are badly burned or pitted theres a resistive or bad ground path so no fire, check and clean and gap points..........

For ignition problems check my Ignition Troubleshooting Procedure

John T
John Ts Ignition Troubleshooting
 
Ignition and starter circuit are 2 different circuits if wire like it was from the factory. The start will spin with or with out the ignition one since it should have a push button switch on the starter that you use a pull rod to work
 
JohnT,
Are you back in Indiana hunting mushrooms? I've gained about 10 pounds this spring. You would think hunting mushrooms one would lose weight.

FYI, my jubilee has no terminal on solenoid or switch to by-pass ballast, so I ran a wire off the starter to the coil. Then had to install a diode so current could only flow to coil from starter. For me it was a simple fix and didn't cost me anything. Have a box of used diodes.
geo
 
I'm just barely "Back Home Again in Indiana" but no time for mushrooms yet. Maybe see you and old Wilson at a tractor show sometime.

John T
 
try this
a5557.jpg
 
Thanks JMOR. Looks like a 6-Volt schematic? I have converted to 12 volt. Cranks. No spark. has new plugs, plug wires, coil, battery, battery cables, rotor turns, points look ok. I"m working through harness now for any bare spots that could be shorting/grounding. Trying to understand why no spark at coil. It has current to alternator
 
Buy a cheap multimeter and take a DC voltage measurement of the BAT side of the coil (at the coil terminal itself); red lead to the coil terminal, black to the tractor frame. Should be from 6-12 volts depending on if you have a dropping "ballast" resistor or not ahead of the 12V supply line feeding the coil.

If you have voltage at the BAT terminal (with the ignition switch turned on, of course) move the red test lead to the other low voltage terminal on the coil (marked GND). Then crank the engine. If the points are working the meter will jump around as the points make and break contact. This is easier to see with an analog meter than a digital one; and a test light bulb is even easier to interpret. If the voltage stays steady and around the same as what you read on the BAT terminal, your points are stuck open or the wire linking the GND side of the coil to the points is broken. If the voltage is zero, the points are stuck closed or the lead wire running to them is shorted to metal.

No voltage at the BAT terminal means that you have a broken wire between the ignition switch and the BAT terminal of the coil, or the ignition switch is bad. Use the voltmeter to track back as far as it takes to find the missing voltage; whatever is between the "good" point and the "bad" point has to be the problem.

If you don't want to invest in a voltmeter (they are cheap and well worth the time they save, IMO) you can try the "farmer expedient" for spark checking: unplug the high tension wire running from the coil tower to the distributor center socket at the distributor (i.e., leave one end plugged into the coil) and tape the bare contact so that it is about 1/16 inch from a ground point (any piece of metal that is bolted to the frame, painted or not). Then remove the distributor cap, rotor, and the plastic points shield (if equipped). This exposes the points. Turn on the ignition switch and crank the engine until the points fully close. Then use a small screwdriver to manually flick open the points. If you are getting power to the coil and the wiring to the points is OK (and the points aren't burnt) then you will see a spark at the points and at the place where the coil wire is almost touching the tractor metal part. The high tension spark should be fat, blue, and audible. No sparks= no current through the coil.

Using cheap condensers (those from China in unmarked white boxes) is asking for trouble. These open up internally and allow the point faces to burn due to arcing. Burnt points cannot conduct electricity and the engine will suddenly stop running (and not start) just as if you had switched off the ignition. I don't think highly of Chinese points either (the point contacts aren't ventilated in any that I've seen) but the condenser seems to be the main problem.
 

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