JD X749 Dying after 30-45 minutes

[Kyle_in_Tex]

Here's another JD overheat thread...
https://www.tractorbynet.com/forums/john-deere-lawn-garden/355570-deere-site-reviews-indicate-x754-2.html

 

[Diggin It]

Fuel Sender in tank
New P/N
FUEL LEVEL SENDER, WITH ANGLED CAP

A fuel sender doesn't have anything to do with sending fuel to the engine. It's a float switch that sends a signal to the fuel gauge on the dash.

Now that everybody is mentioning it, the one problem I had with my JD5300 was when it suddenly died, and was caused by the most repulsive looking crap in the fuel pick up line.

Algae. Are you using any kind of biocide in your fuel?

 

[Kyle_in_Tex]

A fuel sender doesn't have anything to do with sending fuel to the engine. It's a float switch that sends a signal to the fuel gauge on the dash.



Algae. Are you using any kind of biocide in your fuel?

It could be clogged.

 

[Mike VS]

Here's another JD overheat thread...
https://www.tractorbynet.com/forums/john-deere-lawn-garden/355570-deere-site-reviews-indicate-x754-2.html

I didn't read anything there that seems like my problem.

 

[Mike VS]

A fuel sender doesn't have anything to do with sending fuel to the engine. It's a float switch that sends a signal to the fuel gauge on the dash.



Algae. Are you using any kind of biocide in your fuel?

No, to be honest I never have. I guess I will from now on.

 

[Kyle_in_Tex]

Here's another JD overheat thread...
https://www.tractorbynet.com/forums/john-deere-lawn-garden/355570-deere-site-reviews-indicate-x754-2.html

I didn't read anything there that seems like my problem.

On that thread, their mower deck PTO's are cutting off from over heat. Just wondering if your's has a system that cuts off the whole thing?

 

[Mike VS]

On that thread, their mower deck PTO's are cutting off from over heat. Just wondering if your's has a system that cuts off the whole thing?

Not that I'm aware of. If I hit the brake or back up, it will disengage the PTO, but I haven't seen it ever turn off.

 

[radios1]

On that thread, their mower deck PTO's are cutting off from over heat. Just wondering if your's has a system that cuts off the whole thing?

the only thing that will shut down a diesel engine is the fuel cutoff solenoid which is not the problem because it gets constant power, so it's not that, so it can be a blockage somewhere, or the fuel lift pump is cutting out..

 

[Mike VS]

the only thing that will shut down a diesel engine is the fuel cutoff solenoid which is not the problem because it gets constant power, so it's not that, so it can be a blockage somewhere, or the fuel lift pump is cutting out..

Yes, at this point I'm sure you are right. Now I have to find time and start checking all the lines. But you have to admit... it is really strange that a blockage is stopping it like clockwork after 45 minutes or so.

 

[Mike VS]

Some of these units are set up so that if they begin to overheat, the PTO will be purposely shut off to lighten the load.
No, that doesn't apply here, but that is what Kyle was getting at.

That was one of my early tests when it would die. I would immediately disengage the PTO and see if the engine would come back to life, it had no effect. I might be able to get on those fuel lines today and end this once and for all.

 

[Diggin It]

There is an issue with some gasoline engines where a spark coil will work fine until it gets too hot, then will fail, killing the cylinder to make the engine run rough or shut down. I'm not familiar with diesels, but is there anything like that possible?

 

[Mike VS]

There is an issue with some gasoline engines where a spark coil will work fine until it gets too hot, then will fail, killing the cylinder to make the engine run rough or shut down. I'm not familiar with diesels, but is there anything like that possible?

No... Diesels don't use a spark for ignition, nor do they have coils.

 

[Diggin It]

Understood, but is there some electrical component that could overheat and cause shutdown ... a solenoid somewhere?

 

[radios1]

Understood, but is there some electrical component that could overheat and cause shutdown ... a solenoid somewhere?

that's called the fuel cutoff solenoid, which shuts the engine down when you turn the key off, it has been changed, and the voltage to it monitored, it's not the problem..

 

[Mike VS]

Just a little update... I have been swamped with work and have not been able to look at the fuel system, but I did cut the grass today and yes it died 35 minutes later. So with the few minutes I had I opened the hood to look it over. First off I see that the fuel pump is mechanical, so that rules out it having anything to do with the problem. I then looked over the fuel filter area again and saw the fuel shutoff valve is part of that body. When I can, I'm going to start there and work my self backwards to the fuel tank. Reason being is I feel that building heat is a factor and there isn't any of that in the tank or fuel pickup.
Maybe with built up heat the dirty fuel is gelling or expanding. I just don't get why it would un-plug seconds after shutting down. Also I did another little test today while cutting; As soon as it started to die, I immediately pulled back the throttle and cut the PTO. It sputtered but stayed running and within 10 seconds was back to normal. Of course it lasted about 2 more minutes before dying again.
Hopefully I can get out to it soon.

 

[Mike VS]

I had a chance to take the fuel filter housing and fuel shut off valve apart... It was so clean it looked new. Inside the fuel filter housing there was zero sediment or scum on either side of the filter. All fuel passages and the valve internals are shiny new.
So, on to the fuel lines and fuel pickup in the tank... Not easy access, maybe this week.

 

[mini14]

Just because the fuel pump is mechanical doesn't mean it's working correctly

 

[Mike VS]

Just because the fuel pump is mechanical doesn't mean it's working correctly

True, but an intermittent problem like this one would make it pretty unlikely that it is the problem.

 

[Mike VS]

View attachment 660495



Your system has a fuel line from the tank to the transfer (supply) pump on the lower part of the injection pump. From the transfer pump, fuel goes through the filter and back into the upper part of the injection pump. Before you tear into the tank, I would look at the lines to the filter and back up to the top of the injection pump. I would also look at opening up the transfer pump. These checks are fast and easier than digging into the tank.

Ok, I was calling it a fuel pump and you say it's a transfer pump. On a 4 stroke these are only a mechanical diaphragm working off a cam. What does this do differently and you think the inside of this pump is clogged?

 

[Mike VS]

They have a diaphragm, but they also have check valves.

Got it, I'll check them.