Electrkical challenge

You guys have given me such good information on my 720 John Deere thought
I would ask about another tractor we are working on. It is a 1945 (?) Minneapolis
Moline. I have juice to the distributor but not to plugs. I have replaced the
points and condeneor, What else could be stopping the electricity getting to the
spark plugs? Should I look at replacing rotor and distributor? Any other thought?
Thanks in advance.

Clean points rotor and cap so all contacts are bright, just cause you put in new points don't mean they are clean.

What wire to the distributor are we talking about ?????

Are we talking about the battery voltage wire that goes to the bolt on the side of the distributor and to the points.

Or are we talking about the high voltage wire that comes out the coil into the center of the distributor cap.

If it is the later you are way past the points condenser and coil.
They all have to work for you to get spark to the center of the cap.
Only thing down steam from here is the cap; rotor; spark plug wires and spark plugs.
So keep tracing the spark.
You got spark to the cap.
Do you have spark out the cap to the plug wire.
Do you have spark through the spark plug wire to the plug itself.

If it is the former post back and we can go over how the primary system (points and condenser) work.

John in LA,

Excellent post. Comprehensive and understandable.

Tom in TN

Many times, I find new points have a film of oil on them that can keep them from contacting. Usually just pulling a piece of note paper through them will clean them or fine sandpaper.

95% of the time a gas engine will stop with the points closed. if you measure voltage going to the distributor from the coil, the points/condenser is likely not doing its job. With the cap off, looking at the points, are they closed? If you turn on the ignition, the points should ground the wire going to the distributor. Thus there should be no voltage at the distributor connection. If there is, the points need to be cleaned. Use an insulated screw driver (plastic handle) to touch across the points. if there is a small spark there, the points, for sure need cleaned (even new) with the points held open (maybe a plastic fast food knife) there should be voltage at the movable point. Jim

ya'll forgot 2 basic things IS THE GAP SET PROPER and is rotor bug turning when engine is cranked over?

You state I have juice to the distributor but not to plugs.

1) With the tractor not running and ignition ON the points are normally closed SO THERE WOULD BE NO JUICE/VOLTAGE TO THE DISTRIBUTOR Thats normal and correct HOWEVER with ignition ON there should be voltage on the coils input (NOT output to distributor) side.

2) If the ignition is on and engine slowly cranked over a test lamp on the distributor (output side of coil) should flash ON when points are open and OFF when they are closed

3) If theres juice/voltage to the distributor ALL THE TIME as you indicate she will never fire because the points have to close (IE zero voltage on coils output) to conduct coil current..If theres voltage ALL THE TIME the points are bad or must not be closing or wired correct

4) In the event the above were all correct, there can still be distributor cap or rotor problems so the plugs arent firing

To find the cause of no fire work through my Ignition Troubleshooting Procedure linked below it will help find the problem

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

Give this a try and post any questions

John T
John Ts Ignition Troubleshooting

I may be wrong but [b:654c4848f0] I have juice to the distributor but not to plugs[/b:654c4848f0] sure sounds like he has spark from the coil but not to the plugs. That is why I asked for clarification.

But if I am right you guys are just chasing your tail and wasting your time with these post about points and may confuse the electrical challenged even more.

They make a spark plug wire tester you just lay on the wire while it's being cranked or running. If you are actually getting spark at the coil wire but not the plugs then the distributor cap or rotor is bad.

PS, when you say

I have juice to the distributor but not to plugs.

Do you mean A) Juice to the distributors small side terminal that connects to the coil (If there ALL the time the points arent closing or wired right (see my post below) orrrrrrrrrrrrrrrrrrrrrrrrrrrrrr

B) Theres Juice High Voltage out the coils top HV tower to the distributor caps HV tower BUT NONE TO PLUGS ????? Iffffffffff so there may be a dist cap or rotor problem

Let us know and work through my Troubleshooting Procedure

John T
John Ts Ignition Troubleshooting

Do the points spark if you manually operate them, if they do look for issues in the cap and rotor or coil issues. If not, you are not getting power to the points. The toughest one I had was a bad insulator on the bolt to the points. It sure looked good.

Try cranking it over in the darkness ,you should get some kind of light show, if wires leaking ,bad cap ect