Ignition question

[Pk1948]

I have a 1949 WD, converted to 12 volts. It has been a real workhorse but lately has had trouble starting. I found that, even with a fully charged battery, it doesn't seem to be getting current to the ignition system while the starter is engaged. It will start, however, when I let up on the starter. I had replaced the points last summer, if that means anything. Any ideas?

 

[old]

Starter might be getting weak and pulling to many amps form the system and that will cause that problem. Or it could be depending on how it is wired an ignition switch circuit problem. One way to check for a curcuit problem would be to hot wire it

 

[Lexington Jim]

Your ignition switch is bad. To check run a wire from + of battery to + on coil and then crank.

 

[Anonymous-0]

Does it hve a white ballast resister on it. Check to see if it's bad.

 

[old]

If the resister was bad it would not run at all since if bad they cause an open circuit

 

[Anonymous-0]

X2 on Jim's Diagnosis. I have several D series Allises, and sooner or later all seem to get it.

 

[chalmersbob(Pa)]

we are assuming that it was also converted to battery ignition, correct? If it still has a mag, that is another issue. Bob

 

[Kentb of SWMO]

I vote for a bad ignition switch. Check if you have voltage on the PLUS side of the coil WHEN THE ENGINE IS CRANKING. I would bet there is not any voltage but when you let is off crank to run then you will have voltage.

Kent

 

[Paulinkansas]

I had a similar problem with my D17. I removed the key, sprayed some battery terminal cleaner (the yellow foam stuff) in the keyhole, inserted the key and worked it back and forth, then sprayed some electric contact cleaner in there and repeated the process.

 

[Brian Jasper co. Ia]

Have your 12V battery tested. High probability it has a bad cell. It cranks but won't fire up until you release the starter right? Ran through the same thing on an Oliver converted to 12V. It cranked fine because the starter is for 6V. The ignition system would not fire under compression due to the cranking voltage dropping below 9.6V. I tested the battery and it had a bad cell. A new battery and it fired right up reliably. I highly doubt the ignition switch has a problem.

 

[Sid]

What Brian said. The starter on a WD is manually engaged. The ignition is on or off. Unless that has been changed I believe you can rule out the ignition switch as the problem.

 

[David Grubb]

As Maark said those Ballast resisters do go bad. Don"t ask me how I know this. It is a cheap and easy thing to replace and see what happens. Better yet is to put on a coil with an internal resister.

 

[JDemaris]

Any gas tractor (with battery ignition) is going to have more spark-potential when the engine is NOT cranking. That because in a 12 volt system, that voltage is intended to drop to around 9 volts when the starter motor is drawing current. The second you let off the starter, system voltage will spike to over 12 volts. So, when you're cranking, the coil only gets 9 volts and when not cranking - gets over 12 volts.

Then you've got the other possible issues. Do you have an external resistor, or not. Do you have a resistor bypass or not.

I'm also wondering what coil you're using.

Take an ohm-meter and measure across the two primary terminals on the coil (with all wires disconected from it).

If it reads between 1.2 and 1.8 ohms that coil is made to make good spark at 4 volts.

If it reads 2.2 to 4 ohms, that coil needs at least 9 volts to make good spark.

Once you know what you have, then take a voltage reading at the coil when all is hooked up and engine is cranking.