JD X749 Diesel keeps dying out while cutting.

[Mike VS]

Hi guys, Kinda new here so bare with me...
I have a JD X749 - 4 wheel steer/ 4 wheel drive diesel powered mower that is the best thing since sliced bread! I have had it for over a year and put near 50 hours on it with zero problems.
Now I do... While mowing today it suddenly died from full RPM. It did the same thing last month at which time I freaked out and parked it while I pondered the problem. At that time I tried restarting it after a 1/2 hour and it immediately fired up and continued running until today. This time when it died I gave some quick testing to discount possible problems. When it died I immediately tried restarting... Yup, fired right up and continued cutting for 2 minutes until it started dying again. This time I disengaged the PTO (cutting deck) to see if there was any load problem. Nope, just finished dying out without any effect. Again it restarted right back up and soon died again in a few minutes. I tried to throttle back while disengaging the PTO again. Zero effect as it just petered out from full RPM. This time I stopped, opened the hood and checked the obvious; Oil good, coolant good, temp very good running with gauge at 50% mark, air cleaner good, all hood breather screens clear. Fuel level above 75%, Nothing found at all, but there was a bigger gap this time before restarting it (just like last month). Again it fired right up with no hesitation and continued cutting until I finished 15 minutes later.
I know gas engines pretty good but I'm new to diesels. It acted like it lost spark but that obviously is not the case. There seems to be a correlation to the amount of off time before restarting. I did the maintenance about 20 hours ago changing the oil, fuel and air filters. Also the seat cut out switch has been disabled so I don't think it's that.
I'm wide open to suggestions if anybody has any guesses. Thanks

 

[Richard001]

Mike,

I just checked with Tractor Data and I got this: 2008 - 2012 Select X700 Series

So I am wondering, are you the first owner, if so, how is it that the last X794 was made in 2012 and you are saying that you have had this tractor for about a year.

Richard

 

[Mike VS]

Correct Richard, I bought it used a year ago.

 

[Richard001]

I did the maintenance about 20 hours ago changing the oil, fuel and air filters. Also the seat cut out switch has been disabled so I don't think it's that.

So lets see if I understand this correctly. The tractor worked fine last year and now, after you did some service on the tractor, it's acting up.

Is it possible that something you did during the service is causing this problem?

Think back about what you did and what you removed and/or replaced. Perhaps something didn't get put together properly.

Richard

 

[Mike VS]

No problems after service. I did that 20 hours ago... that is about 6 months and 10 cuts ago.

 

[zzvyb6]

Safety (seat, pto, parking brake) systems, fuel supply, temperature.

 

[Deere Dude]

I have a X740 so fix might not be the same as yours. My mower would continue to shut off and found the screen before the radiator was plugged a little bit but the oil cooler before the radiator was plugged and the radiator behind the oil cooler was plugged also. The temp was warm but not in the red zone.

 

[Mike VS]

Ok, when you say plugged do you mean the fins were filled with debris? My temp has been on the low side all along, and today was even lower due to the cool temps. I will check it anyway tomorrow. Did it die suddenly or slowly cough to a halt?

 

[Mike VS]

"Safety (seat, pto, parking brake) systems, fuel supply, temperature."

Of all those, it seems mostly like temp by the way it will restart every time. But it looks and feels cool as a cucumber. I'll be checking that more closely.

 

[ruffdog]

I've got a x744 and my dad has a x749. Have you ever pulled the side panels and the radiator screen (LH side) and cleared out the debris? Take a air wand and blow from the engine side of the radiator to clear the dirt from the fins. stick a light on the rear side and use a mirror on the front side to SEE if the radiator is really clear. You should be able to SEE through.

 

[beenthere]

There is a screen ahead (actually behind on the steering wheel side) in the air stream through the radiator, and it pre-screens the air to catch the larger grass and debris.

Be sure (IMO) to only blow it out with air, as water will make mud and that mud will cake up in the radiator fins, and be near impossible to clean out.

But the issue sounds fuel related.. and I'd look for blockage in the fuel line leading to the fuel filter. Possibly algae in the fuel tank from previous problems. Outside chance there is water in the fuel, but assume changing out the fuel filter took care of that issue. Be sure the fuel filter is in the correct way.

 

[Mike VS]

Well the screens are clean as I always blow it off with my backpack blower after every cut. Today I will do this very thing and give it a good look. Being that I am not too familiar with diesels, I was wondering if they generally act like this when they overheat? Gas engines just start to run bad when they overheat.

 

[boomer1025]

When it shuts down check and see if you have power to the shutdown solenoid with the key on.

 

[ruffdog]

Here is what a stop solenoid looks like. It should be attached to your injector pump.
New John Deere Lawn /Garden Tractor X74 X744 X748 X749 X595 X495 Stop Solenoid, Thermostats - Amazon Canada

 

[Mike VS]

There is a screen ahead (actually behind on the steering wheel side) in the air stream through the radiator, and it pre-screens the air to catch the larger grass and debris.

Be sure (IMO) to only blow it out with air, as water will make mud and that mud will cake up in the radiator fins, and be near impossible to clean out.

But the issue sounds fuel related.. and I'd look for blockage in the fuel line leading to the fuel filter. Possibly algae in the fuel tank from previous problems. Outside chance there is water in the fuel, but assume changing out the fuel filter took care of that issue. Be sure the fuel filter is in the correct way.

WOW!
Isn't it funny how you know about certain things and it takes the thinking of another to realign your brain? The interior screen WAS 70% blocked with grass despite the radiator and outer screens being super clean. I knew about this interior screen as I had done a thorough cleaning last year when I bought it, but obviously forgot about it. As I was inspecting the engine compartment and looking at the radiator from the engine side I'm thinking "This isn't the problem..." Then I get to the inside and I almost fell over! Time will tell if this corrects it, but I have no doubt. This apparently has a high temp shut off linked to the solenoid that Ruffdog and Boomer suggested.
A big THANKS to everybody who gave their opinion!!! Hopefully I wont be back here with this problem any more.

 

[bruceatlam]

Well, let's hope that you've found your problem. But, just in case you haven't found it and the same thing happens to you again, check the vent hole in your fuel cap. The symptoms that you report are the classic symptoms of a plugged fuel cap vent. A plugged vent will allow a vacuum to build in the fuel tank that will, over time, choke off your fuel flow and kill the engine.

 

[Mike VS]

Thanks Bruce, something else I would not have thought about.

 

[ruffdog]

Thanks Bruce, something else I would not have thought about.

Easy to check....when it dies, loosen the cap and listen for the sucking sound. Then, does it start right away?

 

[kthompson]

Had a wasp that died in my fuel tank and it would get sucked onto the fuel outlet doing the small thing. Hard to see a black wasp in a fuel tank without a flashlight, was fortunate it was not hard to get it out. I will also say had same thing to happen with a Kawasaki gas engine and it was the throttle body. Took it to two local shops before it was found and with less than 125 hours total cost was over $1500 out of my pocket. Burnt me.

 

[Deere Dude]

Ok, when you say plugged do you mean the fins were filled with debris? My temp has been on the low side all along, and today was even lower due to the cool temps. I will check it anyway tomorrow. Did it die suddenly or slowly cough to a halt?

The oil cooler was plugged on mine and after the oil cooler the radiator was getting plugged. I had to unclip the trans cooler and pull it out of the way to clean it.

If I recall the temp was high but still workable but the tractor mower deck would have to be reengaged after every reverse direction. Yours is newer so they probably put more features on it.