[JD Driver]

Agree with ttazzman. If you are mowing with the tractor and you come off the seat because the tractor is rolling over, you want that safety circuit to shut down the engine.

As another example, if someone driving the tractor passes out and falls out of the seat, you want the engine to shut down to keep the operator from getting run over (or mowed over).

I was using my JD 455 diesel mower one day, and was backing up and not paying attention to the low tree limb behind me which struck the back of the seat pushing me forward and pinning me into the steering wheel. I remember feeling that I couldn't get my foot off the reverse pedal. Thank goodness the safety system shut down the engine as soon as the seat switch was broken or I might have been seriously injured. It is hard to stop a 1,000 lb mower.

 

[JD Driver]

soooo no one knows of an improvement for this shut off device? its miserable having to remove it every 5-6 hours of usage!!!!!!!!

The real question is why you are having to do this at all. Unless I have missed something, I don't recall others having to remove their fuel shutoff solenoid every 5-6 hrs.

My 2004 4610 uses the same M810324 fuel solenoid valve, and I have never had to remove it in almost 1200 hrs of operation.

Perhaps the solenoid "pull-in" circuitry in your tractor is not providing adequate current, and thus your activity of periodically cleaning the solenoid somehow makes up for this and allows it to barely pull-in and start.

One possibility is that the thermistor used in the pull-in circuitry has gone bad and your solenoid is receiving the sustaining current for the primary solenoid coil, but not the extra pull-in current to activate the separate pull-in coil for a few seconds prior to starting.

I would also remove the K3 fuel shutoff relay and K4 engine run relay, use a scotch brite pad to clean the socket contacts on the relays, spray contact cleaner into the relay sockets, and replace. If the contact resistance for one of these relays has gotten high, there may be some voltage drop across the contact that is making operation of the fuel shutoff solenoid unreliable. You could also buy a new relay of this type and try it in each of the K3 and K4 positions to see if that makes a difference.

Replacing the M810324 fuel solenoid is something else to try if you have not already.

 

[JD Driver]

Too bad he didn't turn the key to ON while watching the solenoid when he had it removed before doing anything else. I would like to see if the solenoid pulls in or not before he removes the oil.

@dvice - when you are having a starting problem, and turn your key to ON, do you hear the loud clunk indicating that the solenoid is retracting? The next time you have a starting problem, please remove the solenoid and watch it while turning the key to ON to note whether or not the solenoid pin retracts before doing any cleaning. You could even measure the pin retracted length (protruding from the solenoid body) both before and after cleaning to see if that cleaning action actually does anything to make it retract further.

This solenoid lives in an oily environment and even has an o-ring seal to keep the oil in the pump, so it seems odd that this is really the problem.

Again, if the solenoid pull-in coil is not being properly energized by the pull-in circuit with the thermistor, your solenoid will often not have sufficient power to retract and allow the engine to start.

BTW, using a 1/4" drive socket, ratchet, and extension makes it easy to remove this solenoid. The bolt in the back is easy to get to with the proper tools.

 

[JD Driver]

@dvice, thanks for taking this data and pictures. From your findings, it is clear that the oil laden fuel shutoff solenoid is harder to retract that one which has been emptied of oil.

Not sure that we can yet declare that this is not an electrical problem. Even though there is clear evidence that your tractor is not able to retract the oil laden fuel shutoff solenoid, it is entirely possible that this is normal and a tractor with a healthy pull-in coil and pull-in coil drive circuit has no trouble providing the additional force needed to retract an oil laden solenoid.

The fuel shutoff solenoid has two coils, the hold-in coil (used only for starting) and the pull-in coil (for both starting and running). The service manual says that the resistance of the pull-in coil coil measured across the A to B terminals should be 0.4 ohms, but it has been my experience that a fuel shutoff solenoid pull-in coil can work fine with up to 1.4 ohms, and the hold-in coil resistance is often up to 24 ohms. The important thing is that the pull-in coil is not burned out (leaving only the weak hold-in coil to overcome your fuel laden solenoid). If you measure an open circuit between terminals A and B, the pull-in coil is burned out.

It is my understanding that the 4X00 series of tractors which use the thermistor based pull-in circuit are hard on the pull-in coil, and may overheat them and burn them out earlier than later tractors like my 4610 which utilize a far better timer based design without a thermistor. The 4X10 tractors only apply current through the pull-in coil for 3 seconds after the key is turned on, and are thus much kinder to the pull-in coil.

If the fuel shutoff coils look fine after measuring the resistance of the two coils, I would next focus my attention on the pull-in coil drive circuit. If your thermistor driven pull-in coil is not being energized, it could explain why the oil laden solenoid cannot retract against the added pressure created by the oil.

As shown in the above schematic diagram, the pull-in coil is energized when current flows from terminal 30 on the K3 fuel shutoff relay through terminal 87A, then through the thermistor to ground. If either the K3 relay or the thermistor are bad, the fuel shutoff solenoid would be trying to perform its function with only the use of the weak hold-in coil, which wouldn't allow the tractor to start most of the time.

 

[JD Driver]

This is a simple tester I built to verify whether or not the pull-in coil drive circuit (relay or thermistor) has failed. Any button you have access to will probably work. You can get male crimp on 1/4" tab terminals at most auto-parts or farm stores. These terminals are the same size as the spade terminals on the bottom of the K3 relay.

Perform these steps to use the test button.
1. Remove the K3 fuel shutoff relay
2. Plug one of the two leads on the test button into the relay terminal position labeled 30.
3. Plug the second lead on the test button into the relay terminal position labeled 85 (ground).
4. Turn the tractor switch from OFF to ON (don't engage starter yet).
5. Press the test button and you should hear the fuel shutoff solenoid retract.
6. While holding in on the test button, start the tractor, then release the test button to de-energize the pull-in coil. The hold-in coil should remain energized to keep the tractor running until you turn the key off.

If the tractor does not start without using the test button, but does start with the test button, then replace the K3 relay first, and if that doesn't fix the starting problem, replace the thermistor.

 

[JD Driver]

You are welcome. I look forward to hearing how the coil resistance compares between the old and new fuel shutoff solenoid valves, and whether or not just replacing this fuel shutoff solenoid valve will fix your starting problems.

 

[JD Driver]

hello JD Driver... the old solenoid measures 0.6 on A to B. and 11.5 on A to C. on my meter set at 200 ohms. The new Solenoid measures 0.7 on A to B, and measures 31.5 on A to C!!!!! whats that tell me???? i got a chinese solenoid?? when i get a non rainy day Ill start to pull the cowl off and might check the relays and thermistor

The solenoid on my 17 yr old 4610 (which still works well) measures 0.5 ohm from A to B (pull-in coil) and 23 ohm from A to C (hold-in coil).

The service manual for the 4610 provides the 0.4 ohm and 12.0 ohm specification values and says "If resistance does not meet specifications, replace fuel shutoff solenoid". That statement is pretty crazy given they don't provide any tolerance (e.g. 0.4 ohm +/- 0.2 ohm). I would bet that any solenoid pulled out of stock at the dealer will not measure exactly 0.4 ohm and 12.0 ohm.

That is good news that you say your new solenoid has a "snappier" pull in. Let's hope it works great.

 

[JD Driver]

hello JD, Driver, I got the new switch in and started the tractor up...but when i turned the key off, the tractors idle went down, but it didnt shut off. I had to throttle the idle lever to the minimum, to stall the tractor!..I have a video, but its MP4 and apparently thats not allowed here....dont know how to change it...

Hello @dvice,

What "new switch" are you referring to?

 

[JD Driver]

Is this a John Deere supplied M810324 fuel shutoff solenoid valve?

Like you, I would wonder if the plunger length of the newly installed solenoid valve is shorter in the off (extended) position than it should be. This might not totally shut off fuel to the fuel pump, and let the engine continue to run after turning the switch off.

 

[JD Driver]

The safety system on this tractor relies on being able to shutdown the engine at any throttle speed by removing power from the fuel shutoff solenoid, so it wouldn't be very safe to operate it without this feature.

When power is removed from the fuel shutoff solenoid, the actuator rod is forced out of the solenoid and into the pump by a spring. It sounds like the spring inside your solenoid valve may not be strong enough to overcome the force needed to completely shutoff fuel flow at the pump. I measured 4.8 lbs of spring force on an operational solenoid with a digital scale.

 

[JD Driver]

I'm having the same problem I think. So I just picked up a 99 4500 and its not starting, it just cranks and cranks, so I pulled an injector line off to see if I was getting fuel an I was not. so that's when I found out about the fuel solenoid, so I replaced it with one from Deere, and its still not starting, is the solenoid supposed to pull in on its own or not? if i apply a tiny amount of pressure to it in works when I turn the key "wile out of tractor" put it back in and nothing. is it possible that the spring inside the injector pump is getting too week for it to work and I need a new injector? can someone sell me what I should be getting for volts or oms from the pull feed when I turn the key?

The fuel shutoff solenoid has a pull-in coil and a hold-in coil. The fact that applying a small amount of pressure to the plunger on the fuel shutoff solenoid with the key turned on is required for it to retract makes it possible that the pull-in coil is not being activated.

There are lots of threads discussing the fuel shutoff solenoid circuitry. You could start by replacing the K3 Fuel Shutoff relay, and if that doesn't fix it, you will probably need to replace the "thermistor".

 

[JD Driver]

It sounds to me like the solenoid has a non serviceable seal to prevent the oil from getting in it. I assume that seal is failing and causing the problem.

He said he just replaced the fuel shutoff solenoid. Are you saying you think the new fuel shutoff solenoid has a bad seal????

 

[JD Driver]

I was referring to the original OPs problem of the solenoid getting oil behind the plunger. Somewhere the discussion took a turn towards electrical. While that might cause the plunger not to get a proper signal the problem of oil preventing it from retracting is not electrical in my opinion.

It is probably more likely that area of the injection pump is sealed from the oil supply and that seal is allowing oil to get to the solenoid.

I totally agree that this could be a mechanical problem, not an electrical problem, but since @xjustchrisx just replaced the fuel shutoff solenoid, it seemed less likely in this case to be a plunger hydraulic lock issue which is why I recommended first starting with the PTC (called a thermistor) and relay. Most of us with these older tractors have a fuel solenoid shutoff relay on the shelf because we have had one fail - including me on my 4610, and that same relay is used in multiple areas.

It is unfortunate that the O.P. never came back to tell us what finally fixed his 4300!

 

[JD Driver]

before I start tearing into the tractor where would I find the thermistor?

Not sure since my 4610 does not use this part, but maybe someone who has replaced one on a 4500 or other 4X00 tractor will respond.

You can pull the relay and test it with a multi-meter first before replacing if you like. Power initially flows through relay pin 30 to pin 87A and then to the PTC (thermistor). After the PTC warms and opens, the K3 relay energizes and switches the relay wiper to pin 87 to open the pull-in coil circuit (and reset the PTC). If the un-energized K3 relay has low resistance between terminals 30 and 87A, it should be fine to activate the pull-in coil (if the PTC (thermistor) is good).

You can also energize the relay by applying 12 Vdc across relay terminals 85 and 86 (polarity not important), and make sure that there is no longer continuity between relay terminals 30 and 87A.