John Deere 4.5L Turbodiesel shut down issue

[Yo Hoot]

Here's something weird I recently discovered with my 28 Model A powered by a John Deere 4.5L Turbodiesel.
I started experiencing a strange phenomenon when shutting it down. Randomly when I turn the key off, it would continue running for a while. I have a red light push button start button on the console. The light would stay lit and then slowly dim. Once the light was fully out, the motor would shut off. It doesn't do it all the time.
We moved here from SE PA so it gets a little hotter and for longer down here (first clue). This motor has a Stanadyne rotary injection pump.
I believe I found the cause. Who thinks they might know what it is?

 

[Ozymandias]

For sure it's a darn cool ride you have!

 

[MarkEagleUSA]

Fuel shutoff solenoid?

 

[mwilson]

Alternator..?

 

[Yo Hoot]

When the electric fan is running, you turn the ignition off... the engine keeps running for a few seconds. The push-to-start red button, which is always lit when the key is turned on, stays on and then fades out when I turn the key off. Once the red light is all the way out, the engine shuts down. Had to figure out how it was still getting power after the key was off and why it fades out. So I looked over the circuit. The fan should be wired to an always on 12v fused source. It should also be wired through a relay. Previous owner did neither. The reason the engine keeps running when the cooling fan is on is the fan motor is wired to run key-on only and when you turn the key off, it acts like a generator as it spools down and backfeeds the start circuit.... keeping the fuel solenoid open until the fan finally stops. Imagine if you wanted that to happen LOL... it's getting rewired.

 

[mwilson]

Neat.....sometimes it seems like licensing should be required for 12V after some of the hacks I've seen over the years...

I suggested alternator because JD used them for tach feeds and hour meter triggers as well as for charging back in the day...didn't know but someone had jack knifed and black taped their way into one of those circuits....

 

[Alan Reagan]

Fuel shutoff solenoid?

I agree, could be sticking or could be about to die. I had one die and the engine wouldn’t shut down at all. I had to manually work the rod and hold it for about 15 seconds before the engine would shut down

 

[Yo Hoot]

Bottom line.. I took the cover off and juggled everything around. Put the cover back on and not an issue since. Something was sticking.

 

[SRay]

Is that Dodge Brothers car? I love how they look in your photo and the 1928 Dodge Brothers that Steve Darnell has

 

[Yo Hoot]

Is that Dodge Brothers car? I love how they look in your photo and the 1928 Dodge Brothers that Steve Darnell has

It's a 28 Model A. I missed something here in the issues. Went to drive it and it cranked but would not start. I jumped the fuel solenoid to 12v. I heard it click but still no start. That's when I took the top cover off of the IP and jiggled all of the parts around. Did seem a bit sticky but loosened up. Started right up. So there were 2 issues. The first where it stayed on for a short time because of the fan back feeding power and than the no start. It's great now.