656 still not starting and getting frustrated

First, I want to thank everyone for all of the help and suggestions.

The latest update is that I do not get any spark from the coil. I put the old coil back on and couldn't get any spark from it either. I took a coil off another engine and couldn't get any spark with it either.

With the ign. switch on, (but not cranking the motor) I have 12 volts from the positive terminal of the coil to ground. I also have 12 volts from the negative terminal (which is connected to the outside distributor terminal) to ground. John T says this should not be, but with the coil disconnected and sitting on a bench, there is only about 1 ohm resistance across these terminals. So, if you have voltage on one terminal, how can you not have it on the other?

I will replace the cable from the distributor cap to the coil tomorrow, but I don't expect that to work either.

I have had the tractor for 10 years. I put about 50 hours a year on it and it has always run well, but now I'm thinking I have spent more time on it than the thing is worth. If the new coil cable doesn't do the trick, I think I will disassemble the tractor and sell it for scrap iron.

DID YUO GAP THE NEW POINTS OR MAYBE THE NEW CONDESOR IS BAD I HAVE HAD A FEW BAD NEW CONDENSORS

With the points closed you should not get any voltage reading on the points side of the coil as the current should be flowing through the points to ground and any voltage reading you get is resistance between coil terminal and ground. So, if your points are not contacting or open you will have full voltage readings. That is the fact of the laws of physics. Try this, with switch on, hook a small jumper wire,(alligator clamp type works good)to the points side of the coil. Now , holding high tension wire from coil about 1/4 inch from frame, touch the other end of that jumper wire to ground, should get a low voltage arc from that jumper wire, now pull wire away from frame and you should get a spark out of the coil. Just remember this principle, the points are nothing more , or nothing less than a switch that grounds the primary windings from coil and every time that switch opens, the magnetic field in coil collapses around the iron core in coil and creates high voltage in the secondary windings, thus a spark. You are making a simple problem way too complicated.

Your missing something simple here. It's not that complicated of a system. You should have 12 volts from yor key switch to the positive side of the coil. You will only have current from the coil to the dist when the points are closed. Either your points are out of adjustment or your condensor is either bad or the wire is grounding out on the side of the case. Check your spring on the points and your condensor connection.

Voltage only on points side of coil when points are open or not making contact.

Pete23 you are correct on the points being open. I typed one thing while thinking another. Sorry about that.

Don, let me answer your questions:

""""With the ign. switch on, (but not cranking the motor) I have 12 volts from the positive terminal of the coil to ground. I also have 12 volts from the negative terminal (which is connected to the outside distributor terminal) to ground. John T says this should not be, but with the coil disconnected and sitting on a bench, there is only about 1 ohm resistance across these terminals. So, if you have voltage on one terminal, how can you not have it on the other?""""

Okay, IFFFFFFFFFF the coil is on the tractor with ignition switch ON (YES should be 12 volts on coil input to ground) and ifffffffffff its output is connected to the distributor and iffffffffffffff the points are good and closed (as they usually are when its setting there) and the wires okay from coil to distributor THERES ZERO VOLTS ON COILS OUTPUT BECAUSE THE CLOSED POINTS ARE TAKING THAT DIRECT TO GROUND AND GROUND TO GROUND = ZERO VOLTS.

HOWEVER on a bench or if the coils output is NOT conencted to a distributor with POINTS CLOSED THEN THE VOLTAGE ON OUTPUT IS INDEED 12 VOLTS SAME AS ON INPUT

SHES NEVER GONNA FIRE UNTIL THE COIL DRAWS CURRENT AND THAT REQUIRES GOOD WORKING CLOSED POINTS (i.e. zero volts on coils output) AND THEN WHEN THEY OPEN SHE FIRESSSSSSSSSSS


HERES A PART OF MY TROUBLESHOOTING PROCEDURE IF YOU TAKE THE TIME TO WORK THROUGH IT THE PROBLEM SHOULD JUMP OUT AT YOU !!!!!!!!!!!!

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.

NUFF SAID

John T
John Ts Ignition Troubleshooting

I agree with John T I will put a easy to check spin on the problem. Remove the wire from the outside of the distributor. Turn on the ignition ot run position. With this wire in your hand, and the terminal lug sticking out of your fingers, touch it to the metal of the tractor. This will ground the wire (just as the points do!) now (if you measured it you would find no voltage at the terminal on the wire you are holding.)
Remove the wire from the shiny metal, and it will spark a little when you do.
If you take the coil wire and set it so that there is a 1/8th inch gap between it and a ground, and play with the wire you removed by rubbing it on the shiny metal, making and breaking this temporary set of points, the coil will spark. It will not be a great fat blue spark because there is no condenser hooked up, but spark it will. If there is no spark doing this I will blame that wire in your hand, it is bad.
Your problem is either that wire, or there is a open in the connection to the points.
This means thet the little stud that passes voltage into the distributor, is not connected to the movable point in the point set, or the [points are coated with something that does not conduct electricity. This must be the case! Jim