2017 L3901 HST stalling issue

[markbxr400]

Had the tractor serviced at 414 hours (the works - fuel filter, oil and filter, HST fluid and filters, air filter, blade, RC clutch adjustment, etc). Has 442 on it now.

Ran great for about 10 hours of mowing, then while mowing it stalled. Would crank, but would not restart. Let it sit for about 10 minutes, restarted, so as it was late, I put it away for the evening. Next day, as the fuel was low, I put about 8 gallon s of fresh diesel in it. I mowed for about another 7 hours, no issues. Refueled again with fresh diesel when I was done.

Got on it a few days later to go pick up fallen limbs with the grapple. It ran for about 5 minutes and stalled. Would crank over but wouldn't start. Let it sit. Went back about 15 minutes later, it started and I took it back to the barn.

Searched the forums, sounds like a fuel issue. possibly air in the system. I cleaned the water separator (was clean with no water in the bowl and no gunk on the screen, and filled the bowl upon reinstall). I bled the system repeatedly using the bleed screw on the fuel filter.

Loaded it up to take to another property. It stalled repeatedly after about 2 minutes of use. It would crank, but not start. I could bleed with the fuel filter bleed screw and it would immediately restart and run again for about 2 minutes and then stall again. Or I could let it sit for about 10 minutes and it would restart.

It is not missing, sputtering or underpowered when running. I get one small drop in power advanced warning, then a couple of seconds later it stalls. I have not noticed any diesel leaks from any lines, etc.

I'm guessing I am getting air into the system from somewhere as when I bleed it it will restart? I'm going to go replace the new fuel filter with another one to eliminate a bad seal, plugged filter, etc.

I was going to try to bleed at the fuel injectors, but they seem to be buried under the DPF filter,, air filter and fuel tank.

Anyone else experience and solve this or have any other ideas before I load it up and take it back to the shop?

Many thanks!

 

[BigG]

Was the tractor run over the winter? Is there algae in the fuel tank? Look for some debris in the fuel tank. If you can blow some air in the fuel line back into the tank. Pull the fuel line after the filter and check for a good flow of fuel. If needed siphon or drain the fuel so you can clean out the debris. Do not blow thru the filters. Replace the fuel filter again. Often for some reason this fixes the problem.

 

[Fordtech86]

Bleeding procedure for your tractor. I can’t help with repairing but do not try to bleed a common rail system at the injectors! The high pressure side will self bleed.


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[markbxr400]

Bleeding procedure for your tractor. I can’t help with repairing but do not try to bleed a common rail system at the injectors! The high pressure side will self bleed.


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Thanks. That's the procedure I have been following.

 

[markbxr400]

Was the tractor run over the winter? Is there algae in the fuel tank? Look for some debris in the fuel tank. If you can blow some air in the fuel line back into the tank. Pull the fuel line after the filter and check for a good flow of fuel. If needed siphon or drain the fuel so you can clean out the debris. Do not blow thru the filters. Replace the fuel filter again. Often for some reason this fixes the problem.

Yes. I'm down one the gulf coast and used the tractor at least every week or two throughout the winter to build my trails on the property. The fresh fuel thatI dispensed into the clean cans from the local gas station to fill the tractor was also dispensed into my truck. I'm 7/8 way through 35 gallons in the truck with no issues in my truck.

The timing between stalls is odd. It's happened more than a dozen times consecutively now. I was milk-running debris to a dumpster and it stalled at nearly the exact same spot every time, about 2 minutes into each round. It would not restart for about 10 minutes if I didn't bleed the system. When I did bleed it at the fuel filter, it would start right up again, and run for about 2 minutes. I tried running at different RPM's which would alter the run time before stalling slightly. It's almost like it takes a certain amount of time for an air bubble to traverse to some point in the fuel system that then created the stall. Would trash in the system behave the same way?

When I go back out to the property, I'll try to blow through the system, and then change the filter.

 

[BigG]

I would bet on something in the tank that is restricting the fuel and then it gets moved out of the way. Or it is restricted to the point that a little fuel is getting to the engine and runs fine before the fuel is to slow to keep a steady flow so it stalls out. You sit for ten minutes and the line refills and you can go again.

I had this happen and replaced the fuel filter and it ran fine for a short time and then started to cut out again. I put in another filter and never had a problem again with the fuel.

 

[markbxr400]

I would bet on something in the tank that is restricting the fuel and then it gets moved out of the way. Or it is restricted to the point that a little fuel is getting to the engine and runs fine before the fuel is to slow to keep a steady flow so it stalls out. You sit for ten minutes and the line refills and you can go again.

I had this happen and replaced the fuel filter and it ran fine for a short time and then started to cut out again. I put in another filter and never had a problem again with the fuel.

Don't hav e the tractor in front of me. Assuming that the fuel circuit goes from the tank, to the water separator then the fuel filter then the fuel rail? So best place to blow air back to the tank is to pull the incoming line to the water separator, pull the cap on the tank, then blow its backwards? Assuming if I pull the lines between the separator and filter I can blow through those as well?

Thanks again .

 

[Fordtech86]

Don't hav e the tractor in front of me. Assuming that the fuel circuit goes from the tank, to the water separator then the fuel filter then the fuel rail? So best place to blow air back to the tank is to pull the incoming line to the water separator, pull the cap on the tank, then blow its backwards? Assuming if I pull the lines between the separator and filter I can blow through those as well?

Thanks again .

http://kubotabooks.com/AutoIndex/in...file=L3301, L3901, L4701 Workshop manual..pdf

Link to the WSM for your tractor.

 

[BigG]

I am guessing that something got into your tank and it will lay across the opening and block the fuel line. So I would get a couple of clean fuel containers and remove the fuel line from the filter housing and let all the fuel drain out and look inside the containers and the tank.

I am not saying you have done anything wrong but then fuel coming out of the pumps is not as pristine as you would think it should be. So remove as much fuel as you can and blow the line back to the tank and then look for some thing floating in the little bit of fuel that will not drain out.

 

[freewheel3]

It sure sounds like you have something blocking fuel flow from the tank, it could be something as simple as a tree leaf or a bit of plastic candy wrapper. Drain it into a clean container and see if the fuel flows steady all the way until the tank is empty.
Then try to shine a light inside and see if you can spot anything foreign in there.
The other possibility is you have air getting in the fuel delivery system. Check all connections and clamps for tightness. I'm not sure how the fuel leaves the tank, whether it just drains out of the bottom or whether there is a dip tube that the fuel is sucked up through. If it has a dip tube, maybe it has a crack in it, allowing air to get in the fuel system?

 

[fendley]

I went through something very similar with my L3901. Turns out that my square o-ring at the top of the bowl of the fuel separator had a cut in it.

I replaced it with a round o-ring, and have not had any issues.

Take a look at your o-ring to see what condition it is in. Mine looked okay, until I bent it slightly while examining the circumference, and then I found it.

At first I didn't think that was enough to cause my problems, but mine has not died a single time since swapping the o-ring.

 

[sheepfarmer]

Don't hav e the tractor in front of me. Assuming that the fuel circuit goes from the tank, to the water separator then the fuel filter then the fuel rail? So best place to blow air back to the tank is to pull the incoming line to the water separator, pull the cap on the tank, then blow its backwards? Assuming if I pull the lines between the separator and filter I can blow through those as well?

Thanks again .

No that is not correct. Get the wsm Fordtech gave you the link to. Don't randomly start blowing lines out until you understand the circuit. There are check valves and fuels pumps in there too.

 

[markbxr400]

It sure sounds like you have something blocking fuel flow from the tank, it could be something as simple as a tree leaf or a bit of plastic candy wrapper. Drain it into a clean container and see if the fuel flows steady all the way until the tank is empty.
Then try to shine a light inside and see if you can spot anything foreign in there.
The other possibility is you have air getting in the fuel delivery system. Check all connections and clamps for tightness. I'm not sure how the fuel leaves the tank, whether it just drains out of the bottom or whether there is a dip tube that the fuel is sucked up through. If it has a dip tube, maybe it has a crack in it, allowing air to get in the fuel system?

Thanks all, and thanks Fordtech for the WSM. Looking at the diagram, it appears that the fuel is sucked up through a supply tube in the tank, then travels directly to the water separator. It also appears there is a drain petcock somewhere on the bottom of the tank.

I'm going to pull the water separator, check the o-ring while it's off and check to see if I get any flow (assuming it will siphon). Then I'll find the drain petcock and drain the tank into clean containers, and see whether I can see any debris in the tank or in the drained fuel. I'll blow backwards through the line between the water separator and tank suction and again see whether anything was blown back into the tank. Then clean the separator and change the fuel filter. Refuel, bleed and see whether the problem is resolved.

BTW, just to rule it out, I had already removed the fuel cap repeatedly during the issues Sunday to rule out a plugged cap vent being plugged.

Will report back what I find.

Thanks again.

 

[Smokeless]

Just fwiw, was checking my 3901 (187hrs) over recently and found what I thought was a mud smear on the outside of the water filter. Ran the tractor and came back to clean in off and tried to wipe the spot off the plastic housing, could not do it, the mark was inside, and it was about 3/8" long.

So I pulled off the plastic housing and their was inside what appeared a piece of cork gasket. Could not believe it!!!!! Cleaned all out and everything appears fine, but as the fuel lowers, I plan to take a flashlite and peaked inside the tank. Wish I would have taken a pic.

 

[markbxr400]

Problem solved.

Cliff's Notes summary - line between the tank and petcock on the fuel/water separator was plugged.

Now for the whole story. I studied the system from tank through to the fuel rail, using the diagram. Unlike the diagram would seem to indicate, the draw from the tank comes off the bottom. You can find the tank sump and line by looking under the dash of the tractor. The line immediately goes to the fuel/water separator. There is s return line that goes to the top of the tank. In fact, when you bleed the system using the bleed screw on the fuel filter housing, it goes into a tee that goes to that return line.

I closed the petcock, pulled the water separator (which was full of fuel, and clean) and the grabbed some empty clear cans and a couple of funnels and put a funnel under the fuel/water separator housing and opened the petcock. Zero diesel flowed out. My goal was to drain the tank to swab the bottom. My tank had about 10 gallons of fuel. So I had to go ahead and clear the plug in order to drain the tank.

If you loosen the mounting bolt for the water separator housing enough, you can rotate it to see the bottom. There are 2 ports. DO NOT blow into the center port - this goes to the low pressure pump. The second hole near the edge is the port that goes through the petcock to the bottom of the tank. I opened the petcock and blew air backwards toward the tank using a paper towel to create a seal. Didn't tank long and the plug cleared and diesel started flowing freely.

I drained the tank catching all of the diesel. It was very fresh and clear. I caught a couple of small pieces of dirt in my collection bottles.

After draining, I made a giant Q-tip, first with a piece of plastic conduit, then some Romex that I could bend and form to get to different areas of the tank. I taped some tee-shirt material on the end with Gorilla tape, and swabbed the bottom of the tank the best I could. I did not pick up any dirt, gunk, etc on the q-tip. It was very clean.

After draining and swabbing, I cleaned the water filter, replaced the fuel filter and filled the tractor with fresh diesel. I bled the system about 3 times using the procedure in the WSM.

Tractor started right up. I mowed for about an hour just to make sure the problem was solved.

Thanks for everyone's help. I will post some pics below of what I did on my 17 L3901 in case anyone else runs into this issue.

Thanks again!

 

[Fordtech86]

Glad you got it fixed!

 

[markbxr400]

I've tried a half dozen times to post pics. Either my internet, file size or something is prohibiting m e from posting the pics. I will try again later or early morning.