Starter robs the ignition of current.

Frenchy305

New User
I converted my Allis Chalmers C tractor to 12volt and added a one wire alternator but I left the 6 volt starter in, so it spins the engine very fast. But I did have a terminal soldered on the started to I could do away with the mechanical start switch and I added a starter relay and key switch to turn on the ignition and start the tractor. But for some reason the way I have it wired, the starter takes all the current away from the ignition when I try to start the tractor. I have to let off of the starter for the tractor to start. How do I wire the ignition, starter relay, and alternator to keep this from happening?...thanks.
 
Sounds like you just plain have it wired wrong. Maybe have a wire for the ignition coming off the wrong side of the starter switch or some such thing.
 
I'm with Old , the switch is wired wrong . You prolly have the ign. wire on the acc. terminal. It'll run that way , but there is no voltage there in the start position ...
 
Try disconnecting the starter cable from the starter relay.

Then hold the switch to the start position, see if you loose power to the coil.

If you do, it's not the starter taking the power. Could be a bad ignition switch or the ignition is wired
to the accessory position on the switch (if equipped).

The alternator should not be wired through the ign switch. The single 10ga wire should go either to the
ampmeter (if equipped), or directly to a battery source, like the battery terminal on the starter relay.

What did you do with the coil? Change it to 12v, or add a resistor? Either way you want about 3 ohms
resistance across the coil terminals. If it was positive ground, you'll need to reverse the coil polarity.
The + terminal is power from the switch, the - terminal goes to the distributor.

A border line weak ignition can also cause the symptom you describe. Be sure the points, cond, wiring, cap,
rotor, plugs are all in good condition.
 
The key switch could be wired in a way that prevents ignition voltage when in the start position. To assess this, remove the wire at the starter relay (solenoid) and put a test light on the coil input wire. If the voltage is there, that isn't the issue.

If a coil is used that is designed for 12volt operation without a resistor, and if a resistor is used in this case, the coil will probably make enough high voltage to spark when running, but not when cranking. A 12v coil for use with no external resistor, will ohm at 4 to 6 ohms. A coil for use with a ballast resistor, will measure 2.5 to 2 ohms.

A battery going bad, or discharged will also make similar symptoms. Jim
 
Maybe, but I have a wire from the front side of the starter relay going back to power the key switch for the ignition and start wire.
 
(quoted from post at 20:15:26 05/18/15) I converted my Allis Chalmers C tractor to 12volt and added a one wire alternator but I left the 6 volt starter in, so it spins the engine very fast. But I did have a terminal soldered on the started to I could do away with the mechanical start switch and I added a starter relay and key switch to turn on the ignition and start the tractor. But for some reason the way I have it wired, the starter takes all the current away from the ignition when I try to start the tractor. I have to let off of the starter for the tractor to start. How do I wire the ignition, starter relay, and alternator to keep this from happening?...thanks.
ou have it wired wrong. On a points ignition system there are two wires that power the ignition. One supplies a full 12v while cranking and usually connects to a terminal on the starter solenoid and goes directly to the coil. The other connects to the ignition switch "I" terminal and goes to a ballast resistor and then to the coil. The first wire only supply's power to the ignition while the starter is engaged and the second wire only supplies power when you let off the key. So it sounds like you have only the second wire connected properly.
mvphoto21080.jpg
 
I had a similar situation on my Jubilee. I had no terminal to send the full 12v to
coil while cranking. So I attached a wire from starter terminal to the anode of a
diode, attached a second wire to the cathode and ran it to the + terminal of coil. So
while cranking I sent the 12v-.6v to the coil. Now it fires right off. As soon as it
starts, no starter voltage and coil is powered via the ballast. No relay needed.

Then after stripping off the starter drive of my Jubilee and shipping the starter
tooth by over powering the 6v starter with 12v, I ordered a 12v starter form YT.

I couldn't find a 12v starter for my Farmall C, so I use a 5 year 12v lawn mower
battery. It works great. No need to worry about ignition. Farmall has a mag. No more
over powering my 6v starters, damaging starter drives and ring teeth.
 
I don't think it's wired wrong, but I might be missing a wire like one guy said. This is how it's wired: Positive battery cable goes to front side of starter relay, along with alternator wire, and power wire going back to the switch. When you turn the key to the on position power is going to the 12v coil from the switch via a wire from the ignition terminal on the switch to the coil. But when you turn the key to the start position you lose power to the coil. A single yellow wire goes from the start terminal on the switch to a small pole on the starter relay. And like I've said before the tractor runs just fine if you let off the starter and it starts.
 
(quoted from post at 08:22:35 05/19/15) I don't think it's wired wrong, but I might be missing a wire like one guy said. This is how it's wired: Positive battery cable goes to front side of starter relay, along with alternator wire, and power wire going back to the switch. When you turn the key to the on position power is going to the 12v coil from the switch via a wire from the ignition terminal on the switch to the coil. But when you turn the key to the start position you lose power to the coil. A single yellow wire goes from the start terminal on the switch to a small pole on the starter relay. And like I've said before the tractor runs just fine if you let off the starter and it starts.

There should be a terminal on the starter switch, not the relay, that is marker either I or ING. You should have a wire from that terminal that goes directly to the coil if you have a "no resistor required" coil. You may have a resistor in line on that wire with the other type coil. On some automotive applications they used 2 wires to the coil, one directly from the ignition terminal on the on the coil with a resistor in line and another from the ignition terminal on the starter relay to the coil with no resistor. That way it provided full battery voltage to the coil during the cranking cycle and then cut back the volt via the in line resistor once running. You do not need that type of setup on a tractor unless delivered from the factory that way.

Rick
 
(quoted from post at 08:22:35 05/19/15) I don't think it's wired wrong, but I might be missing a wire like one guy said. This is how it's wired: Positive battery cable goes to front side of starter relay, along with alternator wire, and power wire going back to the switch. When you turn the key to the on position power is going to the 12v coil from the switch via a wire from the ignition terminal on the switch to the coil. But when you turn the key to the start position you lose power to the coil. A single yellow wire goes from the start terminal on the switch to a small pole on the starter relay. And like I've said before the tractor runs just fine if you let off the starter and it starts.

I did forget to mention that there is a MANDATORY inline resistor that is mounted right below the AMP meter.

Mine is wired wrong. I will be rewiring it later today. Someone in that tractor's past didn't know what they were doing. I'll see how it starts after it has new wiring. and let you know. They had also assembled the left brake baking plate and bearing retainer in the wrong order.

Rick
 

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