Deere 4200 Fuel selinoid fills with oil

[JimmyDeere]

When my John Deere 4200 had about 100 hours it wouldn't start because (I eventually discovered) the fuel solenoid had filled with engine oil and that pressure stopped the piston from retracting. I replaced it with a new one (I was no longer under warranty because the first year I used it very little). About a month later the same thing happened, but this time I took it out and kept working the piston by hand to get as much oil out as possible,and it temporarily fixed it. Still, I have the same problem after a months use or when its parked on a slope. Can someone point me to a (hopefully easy) fix to this problem?

[dfkrug]

First, welcome to TBN, JIMMY.

The engine oil inside the FI pump is used to lubricate it, as I am sure you
know. There must be a failed internal seal that keeps oil from filling up the
solenoid.

This is one of the few parts of my 4300 I have NOT taken apart.

Good luck, and report back on your fix.

[atschirner]

I'' bet the dreaded thermistor strikes again. The fuel solinoid has two winding, pull in and hold. The thermistor located behind the fuse panel controls the pull in windings. Turn the ignition key on. If you don't hear the "clack" of the solinoid pulling in, touch a ground to the white wire at the solinoid with the key "on". This bypasses the thermistor. Don't leave the white wire grounded too long or you can overheat the pull in winding. Once the solinoid is pulled in you can start your tractor.

If this test leads you to the thermistor it's an easy fix with a soldering iron and a short piece of shrink tubing and a new LVU10323 thermistor from JD. Remove the lower pedistal cover, the part with the fuse panel door. Unbolt the fuse panel and rotate it to expose the back side. The thermistor is connected to a black and white wire that should be long enough to allow you access to replace.

There are two kinds of 4X00 owners, those who have replaced a thermistor and those who will. I replaced mine last month on our 4400 with 980 Hrs.

[dfkrug]

Originally Posted by atschirner

I'' bet the dreaded thermistor strikes again.

My 4300 is the earlier design, with no thermister. My service manual shows
both old and new wiring diagrams, but describes only the later design
that uses the dual coil. It says nothing about how the earlier coil setup
(with no thermister) works.

My tractor's coil looks like it has been replaced and the thermister has
been added. Apparently that themister failing has caused lots of
headaches, including replacing the coil when it was not the problem.