'75 2F won't start, question about voltage at the ignitor and coil (1 Viewer)

[aging fleet]

Hey everyone, hopefully you guys can shed some light on an issue that popped up this week. For background, my 40 has its original 2F with an 81+ dual advance large cap distributor and later (78-80) black box ignitor.

It's been running great all year so no history of shenanigans, but a few days ago when I tried to start it, I got lots of cranking but no fire. I had a minute to mess with it tonight, verified the fuses are good (cleaned and ohm tested), battery is measuring over 12.5 volts. All other electrical items are working. With the ignition at the 'ON' position, I read 12+ volts at the ignitor, and no voltage at the coil. When I try to start the motor, I only get about a .5 volts at the coil. My assumption is that, when cranking, I should see the full 12v at the coil.

I'm pretty sure this is my issue, but maybe I'm just fixating on a voltage reading that isn't the problem. Is there a way to more specifically test the ignitor, or based on what I've already seen, should I be trying to track down a replacement?

 

[Coolerman]

Your 1975 FJ40 coil uses a ballast resistor. From your readings it appears it is bad. It is located under that metal cover.

 

[Swintell]

Interestingly enough my 73 with the F is doing the same thing and through searches I've concluded what the above person says about the ballast resistor. It's a cheap part to throw in. I ordered one off Amazon. Some have said nappa has some but mine didn't and had to order for same price I was gonna buy off Amazon anyway.

 

[bhsdriller]

Can try and bypass the resistor for a short period of time to rule it out

 

[aging fleet]

@Coolerman, I wasn't sure what was under that metal cover, so thanks for your input. I'll start looking for a replacement.

@bhsdriller, I'll need to read up on what the resistor actually does, but bypassing may be an option for troubleshooting purposes. Thanks for the suggestion.

 

[aging fleet]

Just to update this, I bypassed the resistor and got the 40 to start tonight. Wasn't able to get to NAPA in time to pick up a replacement, but I should be able to pick something up tomorrow. Hopefully I'm back on the road shortly.

 

[Coolerman]

Good deal! Thanks for following through and letting us know the rest of the story.

 

[aging fleet]

Good deal! Thanks for following through and letting us know the rest of the story.

It’s the least I could do. Replaced the resistor today with an Echlin ICR37 from NAPA and she was back on the road.

Thanks again for the help everyone.