JD X749 Dying after 30-45 minutes

[Mike VS]

If there IS fuel in the bowl on shutdown and the solenoid test light remains lit, that leads me back to airflow. How thoroughly have you checked for partially obstructed, collapsed or restricted air intake hoses?

With a gasoline engine, blocked exhaust lines can cause problem with back pressure. Can that be an issue with diesels?

Completely checked out and looks like brand new parts. Nothing is collapsing on intake and I even disconnected the air flow sensor to alert to you dirty filters.

 

[Mike VS]

Air flow wouldn't make it shut off like a switch. I would think you would see lots of black smoke as the fuel mixture gets richer with diesel cough and then stall. It sounds like something is getting sucked dry and it's taking time to fill back up. The longer you wait the more it fills back up. Or something is heating up and shutting off and as it cools back down the cooler it gets (more time) the longer it takes to heat back up and shut off.

Exactly on the money. When there are any of these other problems, the engine gives you clues. This is EXACTLY like turning the key off.

 

[Mike VS]

Two year old thread on GTT discusses what appears to be the same issue, shutting down after a period of time. Mentions a temperature cutoff switch, but there is no resolution to the thread.

We are going in full circles here... That is where I started the discussion thinking it was just that, a defective temp shut off. I was talked out of it quickly.

 

[Mike VS]

Have not read the entire 13 page thread but has the OP had the JD dealer diagnose his JD tractor?

Not yet, but I know what will happen... They will charge $100 an hour waiting for it to die, then do all that I have done. Is there a computer diagnostic that shows past problems like on cars?

 

[Mike VS]

Unless they changed the design of the shutoff solenoid mount in the pump you should be able to remove the shut off solenoid and run the tractor. You won稚 have any safety shut off function nor will the key shut it off. To kill the engine you would have to use a small screw driver to push in the mechanical plunger inside the injection pump. (I suggest familiarizing yourself with this before starting the tractor)
That would completely rule out any electrical issue with shutdown. All safety and engine protection included. If it still shuts down it誕 a mechanical problem. Problem in injection pump, or a restriction in the fuel lines. Likely not air restrictions because it would smoke profusely before it died.
The mention of keeping it from shutting down by lowering the throttle or cutting off the pto indicates a fueling issue. Doing both those reduces the engine load and fueling requirements.

That's an interesting idea. I would have to make a plate or plug to stop oil from coming out, but not too big a deal.

 

[ruffdog]

That's an interesting idea. I would have to make a plate or plug to stop oil from coming out, but not too big a deal.

If it were my tractor, I would try this to totally dismiss the solenoid and ANYTHING that controls said solenoid.

 

[Mike VS]

Three strikes and I'm out!

I'm not dismissing the gravity feed, I just haven't had the time between having to cut the grass as well as everything else.
As for "run mode mechanically", I have no idea what that means at all.

 

[crazyal]

I don't know how the Yanmar fuel solenoid works but on my Perkins it has a rubber tip and is spring loaded. If you kill the power the spring forces it closed. If you remove it diesel will pour onto the ground. I thought that it has been replaced. If it can be removed without causing a diesel leak then that would be worth pursuing. In the end the idea is to try and eliminate everything but the injection pump $$$$. If you can see fuel in the sight glass then the problem must be closer to the engine.

Looking at a picture of the solenoid it looks like a simple pin that pushes in to shut off the fuel (or pushes in to turn on the flow). This tells me that what ever the solenoid pushes is inside the injection pump could also be broken. I tried doing a search for the solenoid but I found two that look like it but one had 2 wires while most had 3. If it does just have two then if it has power when it shuts off then it's not a safety interlock. I remember Mike saying he tested it but I don't remember how. I would try to rig up a light to the connector. If the light stays on when it shuts off then it's not an interlock.

With a 3 wire system you need to find out what the 3rd wire does. I would assume if this is the case that two wires would just be the power when the key is on and and ground. The 3rd wire come from the computer. If the key is turned off the relay would cut positive to one of the two wires. If the computer thinks it needs to shut the engine down it would do something with the 3rd wire (put power on it or turn power off). A simple multimeter would be very helpful to identify the wires and what they are doing. My simple test with a light would still work but you would need two, one for each wire.

With a 3 wire system you could buy a cheap aftermarket solenoid (hopefully not expensive) and remove the wire that goes to the computer from the connector. Try starting the engine. With a multimeter you could measure the voltage coming from the computer. If it's 12v then you could simply connect the 3rd wire on the solenoid to the battery and run it to see if it shuts off. If it's 0 volts then the engine should start with the wire disconnected and again you could run it to see if it dies.

 

[Mike VS]

As suggested in post #125.

Well that is a recent post and I agreed to try it on my post number #133.
I am very open to all of these suggestions but do not have unlimited time. Be patient I'm trying to listen to everybody.

 

[ruffdog]

Well that is a recent post and I agreed to try it on my post number #133.
I am very open to all of these suggestions but do not have unlimited time. Be patient I'm trying to listen to everybody.

Mike, get to it when you can and let us know what you find....will ya? I hope you figure it out. :drink: