620 jd starting problem.

[mantiup]

My tractor starts and runs as long as I keep the starter engaged......stops running when I get off the starter...any ideas??????

 

[Jerry/MT]

You really haven't given us a lot of info to help you. I certainly don't know the particulars of your tractor, and I flunked Mind Reading 101. Ask my wife!

Having said that, here's my best guess.

Assuming your tractor is a gasser, and your ignition primary circuit has a a bypass circuit with ballast resistor in it, then the resistor has failed or the wire is broken in that branch of the circuit.

 

[Tx Jim]

Ditto Jerry's last sentence. More than likely the resistor(parts key 7) that limits the voltage to ign coil while engine is running is burn't out or wiring to resistor is faulty. The reason engine will run as long as cranking motor is engaged is there's a wire from CM switch to coil to give 12 volts while in start mode.
AA5791R Resistor - RESISTOR,IGNITION ADD 29.09 USD

 

[mantiup]

Hey fellas ,sorry you had to read my mind.....my wife tells me what I'm thinking.....I am sure you have nailed the problem....I thought it was something along that line....but I didn't run it past the wife....I am pro feeding with your ideas.....Thank you very much....

 

[mantiup]

Are you fellas parts dealers?......wife wants to know....

 

[Tx Jim]

I was employed by a JD dealer from '65-'87. BTW I think I have a NOS AA5791R Resistor for $15 plus shipping if your wife is interested in purchasing it.