Intermittent start in run position

[75MIKE]

Don't you just love things that happen every once in a while?

New ignition switch last fall and thought it was all fixed.

Began again this morning. Crank and crank and let the key return to the run position and then it will start. Once it's started and warmed up everything works great and starts with the key in start position.

Bad wire at the solenoid, solenoid itself? Thanks for the help.

 

[crankman]

Was it doing the same thing before you put the new ignition switch last fall? Or did it start after you replaced the switch?

 

[75MIKE]

Yes, that's why I was hoping the new switch would fix it, but it raised it's ugly head again.

 

[Broncobowsher]

Bad "I" wire from the solenoid to the ignition. Or a bad solenoid.

The"I" is the bypass during start.

Unless there is more we don't know about like the original solenoid is gone. Using one built into the starter

 

[DirtDonk]

If you have the standard starter relay/solenoid, disconnect the Brown I wire and see if anything changes.
The ignition switch is supposed to give power to the ignition in both ON and START, so the I wire is not supposed to be needed, but when a switch starts to go bad it does kind of act as a backup.
But in this case, something else is going on, because if it was doing it's job and supplying additional power during START, then your engine should fire even when cranking.

If you still have a radio noise suppressor on the positive side of the ignition coil, try disconnecting that as well.

Another test of the ignition switch is to disconnect both the S and the I wires from the starter relay and test for voltage at the Red w/green positive wire at the coil while someone holds the key in the START position.
If you don't have power at that point, either your new switch has gone south for the end of the winter too, or there is something wrong with the resistor wire.

And just so we're clear Mike, is this a stock Bronco, wiring-wise? This is the '75 in your signature line? Is it running a stock Ford Dura Spark ignition?
All of those things might lead us to a quicker solution.

Thanks
And good luck!

Paul

 

[DirtDonk]

And also just for our information, was the old switch you replaced before an original, or very old one? Or was it a more recent install too?

Paul

 

[75MIKE]

Thanks everyone. Yes. it is the stock ignition with the original Duraspark set-up. The ignition switch is an NOS Ford switch bought from a Ford dealership. Just swapped the lock cylinder, so could keep the door locks.

 

[Viperwolf1]

That brown wire at the solenoid is the same as the brown wire at the ignition module (3 pin connector) and it is also directly tied to the red-green wire at the coil. You can ohm test it to see if there's a problem in its path. If the wire tests good it's probably a bad solenoid.

 

[75MIKE]

Fantastic. Gives me a place to start tomorrow morning. Thank you

 

[Broncobowsher]

Even with a new switch there is no guarantee of a hot run in start. That is the job of the bypass wire.

 

[75MIKE]

Just a follow up. The bronco wouldn't start again this morning and could hear it try and take when I came off the starter.

Remembered I had an extra green grommet module and plugged it in and it fired right up in the start mode like it's suppose to. Can't believe I've been fighting this this long. The joys of electronics. Thanks again for everyone's help.

 

[DirtDonk]

Great! But I hope that's it and you're not just running afoul of the "intermittent" part of this issue.

Good luck!

Paul

 

[75MIKE]

I think I'm good as I swapped the modules back and forth 3 times and the spare fired everytime and the "suspicious" one didn't.

 

[DirtDonk]

Great news.
Now to go find another Green grommet module for a spare!

Are they readily available anymore? I heard some of them are, and some are not.
I think I saw one at NOS in San Jose last year, but not sure.

Paul