Help! Tractor tries to start in the "run" position.

Seanachie · Mar 30, 2008

I just replace the wiring harness on my 1972 Ford 4000 (three cylinder diesel). I'm wondering if fixing the jury-rigging has revealed other problems.

I have the three-position ignition switch, which actually has 4 (Acc/Off/Run/Start) positions but it is only designed to remain in three of them (Acc/Off/Run).

Here's the problem: From the "Off" position, as soon as I turn the key to the right to the "Run" position, it cranks the engine. The engine does not start but it keeps cranking until you turn the key back to off. If you turn it all the way to the "Start" position, it still keeps cranking but it never catches and starts.

FYI: The safety start switch (neutral safety) is inop but I just bypassed the connections until I can get a new one tomorrow.

Do you think the ignition switch is bad or does anyone have any ideas what's going on?

Thanks for any help you can provide.

Sean

aczlan · Mar 30, 2008

Seanachie said:
Here's the problem: From the "Off" position, as soon as I turn the key to the right to the "Run" position, it cranks the engine. The engine does not start but it keeps cranking until you turn the key back to off. If you turn it all the way to the "Start" position, it still keeps cranking but it never catches and starts....
Do you think the ignition switch is bad or does anyone have any ideas what's going on?

Thanks for any help you can provide.

Sean

I would say it is a bad switch, if you are restoring the tractor to working condicion I would go to my local autoparts store and get a replacemtn switch, they sell them for dune buggies and the like... ~$25 IIRC

Aaron Z

dqdave1 · Mar 30, 2008

It may be wired incorrectly also.

jinman · Mar 31, 2008

I would completely disconnect the ignition switch and check it with an ohmeter to see that it was working properly. If it is, then you need to check your wiring for a problem.

Seanachie · Mar 31, 2008

dqdave1 said:
It may be wired incorrectly also.

I was thinking it might be that too but I can't figure out any combination of miswiring that would cause it to act like that. Any ideas?

Soundguy · Mar 31, 2008

Jinman gave you all the info you needed.

If the run/start tabs of the ignition switch areinternally shorted, it would cause this.

As for misswireing causing this? check to make sure the line running to the starter soldenoid thru the now bypassed safety switch only feeds off of one terminal.. IE.. make sure 2 wires don't join somewhere due to a previous owners miss wireing.

Start with the switch and an ohm meter though..

soundguy

SPYDERLK · Mar 31, 2008

Seanachie said:
I was thinking it might be that too but I can't figure out any combination of miswiring that would cause it to act like that. Any ideas?

Perhaps the wire going to the starter solenoid is connected to the Run terminal and maybe the Ignition coil wire is on the Start if it is connected at all.
larry

Soundguy · Mar 31, 2008

SPYDERLK said:
Perhaps the wire going to the starter solenoid is connected to the Run terminal and maybe the Ignition coil wire is on the Start if it is connected at all.
larry

I may be all wet here.. but the original poster did say "1972 Ford 4000 (three cylinder diesel)"

So i really.. REALLY doubt there is an ignition coil on this thing!

soundguy

Seanachie · Mar 31, 2008

Soundguy said:
I may be all wet here.. but the original poster did say "1972 Ford 4000 (three cylinder diesel)"

So i really.. REALLY doubt there is an ignition coil on this thing!

soundguy

I think Larry meant the "ignition terminal" on the back of the starter. Turns out that there were two problems: The switch was indeed bad and the new wiring harness had two wires the wrong color, so they got reversed. It's all good now!