JD 4105 no start after warm until it cools

[Wagtail]

any update? having the same issue.

G'day Mate and welcome to TBN from Downunder.

I'd be interested too. However, it's been almost 2 years since the OP last posted with no solution provided.

As I mentioned before, my 'fault' (oh so many years ago) was a biological growth (what is incorrectly called 'diesel algae') in my fuel tank... the 4105 would start & run fine for about an hour. Then it would start shutting down = starved for fuel. Start up, run for a while, shut down.

An inspection camera put down into the fuel tank revealed the 'fairy-floss (cotton-candy) mixed with phlegm' looking growth at the bottom of the tank caused by water. A full clean out of the tank + a diesel biocide solved that problem.

Enjoy the site.

 

[CADplans]

It is the thermistor,,
This "circuit" that holds the fuel solenoid "in the run position" is a careful balance of two electromagnets,
a powerful magnet, and a weaker one.

To simplify,, the thermistor MUST cool off and become more conductive for the two magnets to have enough power to pull the fuel injection pump lever into the "run" position.

Some replacement thermistors come with wires connected,, and what do they do,,??
They put MULTIPLE heavy layers of heat shrink on the soldered assembly,, and the thermistor.
Guess what!?? the heat shrink keeps the thermistor from cooling.

So, what you need, (it is what I needed) ,, is a new thermistor, and "wire tie" the thermistor in the harness in such a way that the thermistor is hanging out in free air.

I changed from the heat shrink covered thermistor to a properly installed free hanging thermistor.
My delay to restart went from 35/45 seconds,, down to 7 seconds.

I think that for my tractor, that is the best that it can get.
The thermistor will always need to cool,, some time WILL ALWAYS be required.

One guy on YouTube substituted a boat horn button for the thermistor.
You then simply push the button while turning the start key switch.

That would work. A side benefit is that this ends up being a kind of hidden antitheft device.

Who would guess that a tractor requires you to push a button while turning the key to start the machine?

BUT, for now, I wait 7 seconds for the restart.

 

[CADplans]

Oh, yea, I forgot to mention where the thermistor is,
it is behind the fuse panel.
I remove the dash, and steering wheel per the manual, to get to it.

If you have 2X-small hands,, you might be able to get to it by only removing the fuse panel mounting bolts.

I have 2X-Large hands,, so, for me,, that will NEVER happen.