Kubota L4701 Tractor fuel issue

[Ohatchee Creek Farm]

My Kubota L4701 had bad fuel in it. Just quit running all of a sudden and would not start again. The fuel water separator filter and fuel filter were full of what looked like sludge. Dealership wanted $13,000 to fix. That's half the price if the tractor! I had them put new filters on, and I brought it home. I am trying to fix it myself. I cleaned the fuel injectors. It's getting fuel into the fuel filter, as I have bled the air out of it and the fuel flows that far. But still won't start. What should I do next?

 

[JP_Austin]

How old is the fuel in the tank? Hopefully you cleaned out the old fuel first and cleaned out all the lines running to the filters? May have plugged injectors. Believe that is a common rail electronic injection system. I'd remove the common rail to verify the quality of the fuel up at the injectors. If it looks good there then the injectors themselves may have issues. You can send them out to be tested and repaired.

 

[D2Cat]

Sounds like you have algae growing. Need an algaecide in the fuel and keep replacing filters until you see clear fuel.

 

[ferguson]

i would bleed injector lines. messy job big pan under engine. i would start at the injector pump & then to the injectors. my 2 cents. And 13k is crazy. Worst case need to by a remand injector pump & injectors.

 

[Russell King]

You probably have a biological growth in the fuel tank.

I am not familiar with your tractor but if it has a common high pressure rail system then it is possible that you would need more professional help to get it running. The advice below is applicable to tractors with mechanical pumps and injectors

I suggest that you drain all the existing fuel out and put some new fuel in the tank and add some biocide to the fuel. Probably at the highest possible amount that the bottle allows.

You may need to remove all the fuel lines and clean them out.

Try to get the treated fuel to the injectors and then let it sit for a day or two to kill the biological material.

Then try to get the tractor to start. Bleeding the injectors usually takes more effort than anticipated. Read your owners manual carefully for the instructions and follow them on bleeding your tractor.

If you get it running then replace the filters again sooner rather than later. They will be removing a lot of debris and clogging up faster than you expect.

Fill the tank completely with treated fuel after you have it running and keep the tank full with treated fuel for a while to kill off any biological growth. I would recommend you always use the fuel treatment from now on.

 

[North Idaho Wolfman]

We are going to run into this more and more as there is now quite a few models out there.
It's nowhere near as simple as crank a few lines and bleed out the air and it will start right up.

First thing you need to know is what codes the tractor displays.
Get the WSM and study every detail about the fuel system, it's not as simple as it's not getting fuel.
Certain codes shut down the fuel system.

If you ran sludge through to the High pressure pump, you will need to remove it and have it rebuilt, I would do the fuel rail and fuel injectors at the same time.
Even starving the the pump of fuel will damage them.

This is really not a DYI / Shade tree repair as there is very little you can do as a complete repair, as you can not read, reset, reprogram the computer to clear the codes.
You will also need a high pressure test kit to test the system.
And any part you have rebuilt will need to be programmed into the computer in order to operate properly.

 

[North Idaho Wolfman]

i would bleed injector lines. messy job big pan under engine. i would start at the injector pump & then to the injectors. my 2 cents. And 13k is crazy. Worst case need to by a remand injector pump & injectors.

There is NO injection pump and you can't bleed the injectors.

 

[fried1765]

There is NO injection pump and you can't bleed the injectors.

Latest tractor technology.......ain't it great?
Take it to a dealer,.... and get your wallet emptied!

 

[Ohatchee Creek Farm]

Sounds like you have algae growing. Need an algaecide in the fuel and keep replacing filters until you see clear fuel.

The dealership did a fuel analysis and it came back normal. I completely emptied the fuel tank and cleaned it. But I will still put an algaecide in.

 

[Ohatchee Creek Farm]

You probably have a biological growth in the fuel tank.

I am not familiar with your tractor but if it has a common high pressure rail system then it is possible that you would need more professional help to get it running. The advice below is applicable to tractors with mechanical pumps and injectors

I suggest that you drain all the existing fuel out and put some new fuel in the tank and add some biocide to the fuel. Probably at the highest possible amount that the bottle allows.

You may need to remove all the fuel lines and clean them out.

Try to get the treated fuel to the injectors and then let it sit for a day or two to kill the biological material.

Then try to get the tractor to start. Bleeding the injectors usually takes more effort than anticipated. Read your owners manual carefully for the instructions and follow them on bleeding your tractor.

If you get it running then replace the filters again sooner rather than later. They will be removing a lot of debris and clogging up faster than you expect.

Fill the tank completely with treated fuel after you have it running and keep the tank full with treated fuel for a while to kill off any biological growth. I would recommend you always use the fuel treatment from now on.

The dealership did a fuel analysis and it came back normal. I completely emptied the fuel tank and cleaned it. But I will still put an algaecide in. Thanks

 

[Ohatchee Creek Farm]

How old is the fuel in the tank? Hopefully you cleaned out the old fuel first and cleaned out all the lines running to the filters? May have plugged injectors. Believe that is a common rail electronic injection system. I'd remove the common rail to verify the quality of the fuel up at the injectors. If it looks good there then the injectors themselves may have issues. You can send them out to be tested and repaired.

We are going to run into this more and more as there is now quite a few models out there.
It's nowhere near as simple as crank a few lines and bleed out the air and it will start right up.

First thing you need to know is what codes the tractor displays.
Get the WSM and study every detail about the fuel system, it's not as simple as it's not getting fuel.
Certain codes shut down the fuel system.

If you ran sludge through to the High pressure pump, you will need to remove it and have it rebuilt, I would do the fuel rail and fuel injectors at the same time.
Even starving the the pump of fuel will damage them.

This is really not a DYI / Shade tree repair as there is very little you can do as a complete repair, as you can not read, reset, reprogram the computer to clear the codes.
You will also need a high pressure test kit to test the system.
And any part you have rebuilt will need to be programmed into the computer in order to operate properly.

I have been concerned about those codes you taking about. Not good news.

 

[whitetiger]

How did you clean the injectors?

 

[Russell King]

Ok that puts this in a new perspective…but how is the fuel analysis normal if the fuel was “bad”? What was bad about the fuel?

I assume you read @North Idaho Wolfman post above so I think you are in a bad position to fix this yourself.

So to restate the problem: tractor was running and then stopped running. The fuel filters were clogged with sludge. The filters were changed. Injectors were cleaned. Tank was drained and cleaned. Tractor was bled to the filter but tractor won’t start.

How did you clean the tank and the injectors?

Did you try to bleed the injectors or just get fuel through the filters?

 

[Ohatchee Creek Farm]

Ok that puts this in a new perspective…but how is the fuel analysis normal if the fuel was “bad”? What was bad about the fuel?

I assume you read @North Idaho Wolfman post above so I think you are in a bad position to fix this yourself.

So to restate the problem: tractor was running and then stopped running. The fuel filters were clogged with sludge. The filters were changed. Injectors were cleaned. Tank was drained and cleaned. Tractor was bled to the filter but tractor won’t start.

How did you clean the tank and the injectors?

Did you try to bleed the injectors or just get fuel through the filters?

I'm not an expert but am mechanically inclined (I've worked on and fixed many of my own pieces of equipment/ automobiles in the past), so like many people I went to YouTube "university" along with using the manual. I used a solvent in the tank and flushed it with clean diesel fuel. I used brake parts cleaner in the injectors and blew them out with air and let them dry before reinstalling.

It's a common rail system. I understand that I'm only supposed to bleed to the fuel filter, and then let the low pressure electromagnetic pump finish pushing and purging any air left in the system through the common rail and on through to the injectors.

Oh, and I was going by what the dealership told me about it being "bad" fuel. I wondered the same thing about how could it be bad if the fuel analysis came back normal. I never did get a straight answer on that one.

 

[Russell King]

I think you are going to need to get the injectors rebuilt or possibly replaced. I believe you will have to get a dealer involved to put information into the ECU (computer) of your tractor if you replace the injectors. The dealer has an Kubota piece of equipment called Diagmaster that is used to put serial numbers in so the computer knows how the injector operates precisely. I also think you need to be sitting down when you see the injector cost!

I will try to stop commenting much since your tractor is common rail and I have no experience with that kind of equipment. @North Idaho Wolfman and @whitetiger are both experienced with current equipment so please follow their advice closely.

If you are getting codes on your tractor you should post them and they will let the techs know what your tractor is doing in more detail.

 

[North Idaho Wolfman]

I'm not an expert but am mechanically inclined (I've worked on and fixed many of my own pieces of equipment/ automobiles in the past), so like many people I went to YouTube "university" along with using the manual. I used a solvent in the tank and flushed it with clean diesel fuel. I used brake parts cleaner in the injectors and blew them out with air and let them dry before reinstalling.

It's a common rail system. I understand that I'm only supposed to bleed to the fuel filter, and then let the low pressure electromagnetic pump finish pushing and purging any air left in the system through the common rail and on through to the injectors.

Oh, and I was going by what the dealership told me about it being "bad" fuel. I wondered the same thing about how could it be bad if the fuel analysis came back normal. I never did get a straight answer on that one.

Posting the codes might help.

If your getting flow to the injectors via the lift pump, more than likely the high pressure pump is in need of a rebuild, as are the injectors as they should not let fuel through.

FYI: You can't clean electronic injectors with brake parts cleaner and a shot of air. it's kind of like peeing in the ocean.