Diesel tractor is stalling. Cause?

[jgradyc]

I have a 15-year-old Kubota B3030 tractor. This spring the engine started stalling. After the engine is warm, it will stall for only one second and then return to running normally. It feels like the fuel has suddenly cut off. This happens about once every 5-10 minutes after I have been mowing for a half hour or so. I have changed the fuel filter. Changing the fuel filter helped, but only a little. I get my diesel from the local gas station for the past twenty years in the same diesel five-gallon can. I put in a new air filter last fall so I don't think that's it. I'll check the air filter again today. I think it might happen more often if the tractor is going uphill or going sideways on a hill with the left side (drivers side if it were a car) higher than the right side. It never seems to last more than one second when it happens. 

Anyway, what is the most likely cause? How can I fix it myself? 

[RED333]

Have you checked for water in the fuel tank? With it happening more often sitting at an angle that would be my WAG.

[MacGyver]

Do you have a fuel/water separator? I’m not a tractor guy - but we’ve always got them on boats.  Condensation over the winter in a tank that’s not full can cause problems just like that.

If there’s a low point in the fuel system, I’d drain a little fuel into a clear container and check for separation.  Water is heavier than diesel - so it’ll be on the bottom. 
 

 

[Grayfox54]

Does it have an electric fuel solenoid?  There's the possibility of a loose / bad connection or worn wire. I'd check that first. 

Could be either water or air in the fuel lines. There should be a drain cock on the bottom of the fuel tank. Open it and drain any water out. While slim, there's also a chance of a small leak on the suction side of the fuel pump that's sucking air in. Check all connections and replace worn hoses. 

 

[Johnny Rotten]

your fuel hoses could be breaking down inside, 

sure it's not sucking air somewhere in the fuel system, since you changed the filter.

does the IP have a return line to the tank? if so install a clear fuel line and see if there are bubbles going back towards the tank.

 

[bersaguy]

It sounds like you have gotten some good options to try. There is a product on the market called Sta-Bil and it is a fuel stabilizer and it comes in 3 different grades. 1 for your cars, 1 for your boats and 1 for Diesel. I used it in the Marine Grade for my boat for years and my Jeep to this day. It removes water from the fuel and prevents anymore from forming. That would be my next move if I were you.....JMHO

[jeff43]

Do you have a funnel with a strainer / screen in it you use when fueling it up? If not  you may have some trash in the bottom of the tank , covering the hole up going to the line and fuel pump.

[FUJIMO]

4 hours ago, jgradyc said:

I have a 15-year-old Kubota B3030 tractor. This spring the engine started stalling. After the engine is warm, it will stall for only one second and then return to running normally. It feels like the fuel has suddenly cut off. This happens about once every 5-10 minutes after I have been mowing for a half hour or so. I have changed the fuel filter. Changing the fuel filter helped, but only a little. I get my diesel from the local gas station for the past twenty years in the same diesel five-gallon can. I put in a new air filter last fall so I don't think that's it. I'll check the air filter again today. I think it might happen more often if the tractor is going uphill or going sideways on a hill with the left side (drivers side if it were a car) higher than the right side. It never seems to last more than one second when it happens. 

Anyway, what is the most likely cause? How can I fix it myself? 

I know this is going to sound odd and make zero sense but how old is the battery ? I've got a smaller Kubota that starting running just as you described last season. I followed the logical options as stated in this thread but near the end of the season the battery finally gave up. I replaced the battery and haven't had a hiccup since. You may be experiencing something else but I thought it was worth mentioning.

 

[-boatman-]

1 hour ago, jeff43 said:

Do you have a funnel with a strainer / screen in it you use when fueling it up? If not  you may have some trash in the bottom of the tank , covering the hole up going to the line and fuel pump.

I've had this happen. I took the tank off and cleaned it and it took care of the problem. 

One think I haven't seen mentioned was the lift pump. When mine went out it still ran for the most part because it still got some fuel but that is because of gravity. The tank is behind the seat up high.  

[gregintenn]

It sounds as if you have compression, and you don’t need spark for a diesel, so You should inspect your fuel system from stem to stern. I bet you’ll locate the problem. Partially clogged fuel line, cracked hose, fuel pump, etc.

 

 

Edited May 18, 2023 by gregintenn

[jeff43]

6 hours ago, jeff43 said:

Do you have a funnel with a strainer / screen in it you use when fueling it up? If not  you may have some trash in the bottom of the tank , covering the hole up going to the line and fuel pump.

The reason I say this is from experience. My fuel tank I pump my diesel out of , on the end of the hose I keep a plastic plug on it to keep bugs and dirt dabbers  out. My son was pumping fuel in it one day and didn’t take the plug off . He started running the tractor and it would smother out and kind of miss. The little plastic plug which is about 1/2” diameter would get sucked over the hole in the bottom of the tank and shut the  off.

[jgradyc]

A big thanks to everyone. I'll look at those issues over the weekend. It has a brand new battery. The problem started on my first mowing this spring and it has continued through two tank fill-ups. I changed the fuel filter, but it didn't solve the problem. I'll go through these options this weekend and give a report when I find the problem. Again, thanks! 

[DWARREN123]

Also check any safety switches it may have.

[Cattle Baron]

My 2010 Kubota started intermittently stalling a few months ago. It would start and run fine then suddenly stall. It would fire right back up and run fine again for awhile then stall. We narrowed it down to the safety switch under the seat. I was an easy, inexpensive fix. 

[jgradyc]

8 hours ago, Cattle Baron said:

My 2010 Kubota started intermittently stalling a few months ago. It would start and run fine then suddenly stall. It would fire right back up and run fine again for awhile then stall. We narrowed it down to the safety switch under the seat. I was an easy, inexpensive fix. 

I don't know if my tractor has a safety switch under the seat. I'll check for it. Thanks.

[jgradyc]

On 5/21/2023 at 9:39 AM, Cattle Baron said:

My 2010 Kubota started intermittently stalling a few months ago. It would start and run fine then suddenly stall. It would fire right back up and run fine again for awhile then stall. We narrowed it down to the safety switch under the seat. I was an easy, inexpensive fix. 

UPDATE: This sounded like it might be the problem since I'm a short, lightweight guy and the problem typically occurs when I'm leaning forward on the seat. However, now I have a new problem. I started the tractor. It was running fine. I tested the seat safety by lifting the seat and it shut off. However, when I put the seat back down, it would not start... not even a click from the solenoid when I turn the key from on to the start position. Since the new problem started when I raised the seat and put it down, I guessed that the problem was related to the seat. 

I replaced both seat safeties and the solenoid won't even click when I switch from the ON to the START position. I checked the new safeties for continuity and they are both working properly. 

I next checked the 30A fuse going to the solenoid. It's good.

What could be the cause? 

Anyone know a tractor mechanic that will come to my house to fix this? I live on Old Hickory Blvd in Nashville on the west side of Nashville near Scottsboro and Beaman Park. 

[jpx2rk]

Any other fuses on the tractor, may have popped a fuse to the seat safety.  

[Miltech]

If it is a hydostatic transmission it has safety switches on the fwd/rwd pedal. If this is slightly out of adjustment it can cause the same problem when trying to start. 

[Cattle Baron]

PM sent 

[jgradyc]

UPDATE: A neighbor heard about my problem when I posted on Next Door. He came over and found the problem in about 20 minutes. It was a blown 5a fuse in the fuse box. The fuse had been jury-rigged to power a radio that I never used. I removed the radio and all the wiring to it. 

I mowed for an hour and the problem never happened again. I guess a wire from the radio was intermittently shorting out and eventually blew that fuse. I think the fuse was to the OPC, whatever that is... maybe some sort of power controller? 

Anyway, my wife is happy that the field is mowed. I'm happy that I don't have to pay to get the tractor hauled to Colemans for repair. I left some tall grass for the deer to bed down at night. It was easy to tell where they had been sleeping. 

Thanks to everyone for your suggestions! This is a great place to get advice. 

[tacops]

Just to add to the discussion in case it helps you or others...I have a Kubota 2013 BX series.  It did the same thing you described in your initial post.  I found that it actually has two in line fuel filters.  One easily accessible but the other is deep within the frame structure and requires a contortionist to change.  Once changed all was good.  I also ran into a similar problem on the wiring / seat.  Mine would start but not turn off.  I had to manually activate the fuel shut off solenoid under the hood.  Long story short, I found that the seat had pinched one of the wires coming from the seat safety switch which shorted and blew the 5a fuse to the fuel shutoff solenoid.  Repaired the wire, changed the fuse and all was good.

[gregintenn]

While it doesn’t amount to much, that type crap sure can give a guy a headache trying to diagnose!

[Frog4aday]

I appreciate hearing what the final issue & fix turned out to be. Thanks for coming back @jgradycand closing the loop on this. I have a Toro ZTR mower doing the same as your tractor so I've been following this thread.