Help!! Kubota excavator won’t start

[Beech123]

I have a kx040-4 it was running fine then shutoff like you killed the switch. Emergency stop button has not been hit. Have fuel coming through the filters and up to the injectors. Any thoughts?

 

[GreensvilleJay]

more info neded..
does it try to start ( starter cranks but no go ) ???
are there any safety switches (seat, seltbelt, ??? ) ???
have you the WSM or at least the electrical wiring diagram ??
does it have a manual shutoff ? Friend's kx41(?) has mechanical lever to stop

 

[Beech123]

more info neded..
does it try to start ( starter cranks but no go ) ???
are there any safety switches (seat, seltbelt, ??? ) ???
have you the WSM or at least the electrical wiring diagram ??
does it have a manual shutoff ? Friend's kx41(?) has mechanical lever to stop

Hi thanks for the response. Yes engine cranks but does not start. It does have a manual fuel shutoff on filter but that’s it. Fuel is controlled by a SCV (suction control valve). No seatbelt safety shutoff. I’ve checked all relays and fuses. No I do not have a WSM. I’ve checked and it’s getting fuel to the injectors, I just do not know at what pressure. It’s a common rail system.

 

[Vigo]

Well, if you've got fuel to the injectors you might have narrowed it down to 'only the hard stuff left'.. great!

I don't know anything about a kx040 specifically, but 'common rail' diesels have to have electrically controlled injectors, so the most likely thing is that the 'computer' simply stopped opening the injectors because it lost a signal or set a fault code or something like that.

So i think you should be focused on the electrical side of the house, whether that's reading fault codes, or interpreting a warning lamp, or in the worst case chasing actual circuit problems with a meter and test light..

So i guess someone who knows about a kx040 should now come in and tell me whether it even has a computer system that can set fault codes! And if so, what do you need to read them?

 

[fried1765]

Well, if you've got fuel to the injectors you might have narrowed it down to 'only the hard stuff left'.. great!

I don't know anything about a kx040 specifically, but 'common rail' diesels have to have electrically controlled injectors, so the most likely thing is that the 'computer' simply stopped opening the injectors because it lost a signal or set a fault code or something like that.

So i think you should be focused on the electrical side of the house, whether that's reading fault codes, or interpreting a warning lamp, or in the worst case chasing actual circuit problems with a meter and test light..

So i guess someone who knows about a kx040 should now come in and tell me whether it even has a computer system that can set fault codes! And if so, what do you need to read them?

Me thinks the OP needs to invest in a WSM!
Everyone who maintains (or attempts to maintain) their machine NEEDS a WSM!

 

[Henro]

I think the suggestion to get a workshop manual is a good one!

I’m surprised though for some reason that the OP‘s excavator being a small one has a common rail system, since for some reason I identify that with the larger engines that require emission controls. Know that I could be totally wrong on that assumption.

Regardless, the complexity of the Common rail system kind of turns me off so I’m glad I don’t have one. At least I don’t think I have one… Since I have a KX020–2 V mini excavator.

 

[Vigo]

Well dang, i looked at a kx040 brochure and now i want things i can't afford.. AGAIN

arrrg

https://www.kubotausa.com/docs/default-source/brochure-sheets/kx040.pdf?sfvrsn=db4b902d_4

Can't disagree with the WSM recommendation!

I'm pretty sure any newer machine with over 25hp has a good chance of being computer controlled common rail because while you could install a DPF without a computer, you can't do a regen cycle without computer controlled injection, so it'd be pretty hard to keep it alive.. So i'd guess there's a near-total overlap with having a dpf, and having computer controlled injectors.

 

[Beech123]

Thanks for the comments. I will order a WSM. I have access to one for an 80 and it seems to be the same setup. The machine is def a common rail. It does have a computer system. I figured out how to get into the system and do a scan. It shows no error codes.
I know the system will show codes due to the fact if I unplug a sensor with key on it throws a fault. I’ve been told that if one injector is bad that the engine will not “fire” due to it being a common rail system. My main thought is possibly a check valve stuck and returning fuel to tank and not allowing pressure to build in system. Not sure if that is possible. Thoughts

 

[Beech123]

Well, if you've got fuel to the injectors you might have narrowed it down to 'only the hard stuff left'.. great!

I don't know anything about a kx040 specifically, but 'common rail' diesels have to have electrically controlled injectors, so the most likely thing is that the 'computer' simply stopped opening the injectors because it lost a signal or set a fault code or something like that.

So i think you should be focused on the electrical side of the house, whether that's reading fault codes, or interpreting a warning lamp, or in the worst case chasing actual circuit problems with a meter and test light..

So i guess someone who knows about a kx040 should now come in and tell me whether it even has a computer system that can set fault codes! And if so, what do you need to read them?

Thanks for the advise. I have tested the voltage to the injectors, when I crank the engine the injectors show voltage. Which makes me think it’s more to do with fuel rail pressure. I’m no mechanic for sure just a lot of late night research and brain storming!!

 

[Vigo]

So I'm not really a 'diesel mechanic' or an 'equipment mechanic' but im an ASE master tech and i do hold a certification in light diesel engines, and know a ton about engine management in general, so take it for what it is.. i don't actually work on a lot of modern diesels (because the ones in 3/4 and 1ton trucks are giant PITA!!).

Injectors generally have constant power either any time the key is on, or anytime the engine is spinning. The computer usually pulses the ground side to actually operate the injector. So if you do something like clip a test light to power and then poke the ground side terminal of the injector connector, you should get a flashing light while cranking if the engine is attempting to operate the injector. If the engine IS attempting to operate the injector, you're probably right that the pressure in the rail is insufficient.

If that's the case, again i don't know exactly how the pressure is made on that machine but on some common rail diesels i'm familiar with in trucks such as a 7.3 and 6.0 powerstroke, the engine's oil pressure is used as a 'base' pressure which a separate high pressure oil pump then 'amplifies' up to the rail pressure. So lack of rail pressure could be related to the high pressure oil pump, OR the low pressure oil pump. Because of that, those engines can be hard to start if the oil is thinned out or at a low level. Which is a blessing, because in my opinion the 7.3's reputation for reliability is partially based on the fact that it's real hard to screw up the bottom end because if your oil quality or oil pressure is low, it won't run enough to make it any worse!

So IF your engine operates in a similar way.. check the oil!! It may have sprung a leak and pissed out enough that it can't make rail pressure for the injectors. Or it might operate totally differently. All i can do is try to relate what i know from being an automotive tech that rarely works on modern diesels.

 

[Beech123]

So I'm not really a 'diesel mechanic' or an 'equipment mechanic' but im an ASE master tech and i do hold a certification in light diesel engines, and know a ton about engine management in general, so take it for what it is.. i don't actually work on a lot of modern diesels (because the ones in 3/4 and 1ton trucks are giant PITA!!).

Injectors generally have constant power either any time the key is on, or anytime the engine is spinning. The computer usually pulses the ground side to actually operate the injector. So if you do something like clip a test light to power and then poke the ground side terminal of the injector connector, you should get a flashing light while cranking if the engine is attempting to operate the injector. If the engine IS attempting to operate the injector, you're probably right that the pressure in the rail is insufficient.

If that's the case, again i don't know exactly how the pressure is made on that machine but on some common rail diesels i'm familiar with in trucks such as a 7.3 and 6.0 powerstroke, the engine's oil pressure is used as a 'base' pressure which a separate high pressure oil pump then 'amplifies' up to the rail pressure. So lack of rail pressure could be related to the high pressure oil pump, OR the low pressure oil pump. Because of that, those engines can be hard to start if the oil is thinned out or at a low level. Which is a blessing, because in my opinion the 7.3's reputation for reliability is partially based on the fact that it's real hard to screw up the bottom end because if your oil quality or oil pressure is low, it won't run enough to make it any worse!

So IF your engine operates in a similar way.. check the oil!! It may have sprung a leak and pissed out enough that it can't make rail pressure for the injectors. Or it might operate totally differently. All i can do is try to relate what i know from being an automotive tech that rarely works on modern diesels.

Wow thanks for the advice I didn’t realize that. I have checked oil level and it is good. But I will check injectors for pulse. Thanks a million for the response

 

[Jchonline]

I have a kx040-4 it was running fine then shutoff like you killed the switch. Emergency stop button has not been hit. Have fuel coming through the filters and up to the injectors. Any thoughts?

No errors showing on the digital display at all?

 

[Beech123]

No errors showing on the digital display at all?

No errors showing. I accessed the dealer service portion of computer and did a scan it comes back clear

 

[Jchonline]

1. is the emergency kill switch up or down? It should be down. You pull it UP to kill the engine.

 

[Beech123]

1. is the emergency kill switch up or down? It should be down. You pull it UP to kill the engine.

The switch is in operating position. If you engage the switch the engine won’t even crank.

 

[Jchonline]

The switch is in operating position. If you engage the switch the engine won’t even crank.

So you are saying the button is down correct? Asking because I saw videos of a few KX series machines that had the button up and it would still crank (but not run). I am not close to mine today or I would try it.

 

[Beech123]

So you are saying the button is down correct? Asking because I saw videos of a few KX series machines that had the button up and it would still crank (but not run). I am not close to mine today or I would try it.

I’m not close to mine either but that’s the first thing I checked. I let my dad borrow it. He unloaded it off the trailer, greased it, trammed 30’ and it just shut off. My machine will not crank if the switch is not in the run position.

 

[Jchonline]

I’m not close to mine either but that’s the first thing I checked. I let my dad borrow it. He unloaded it off the trailer, greased it, trammed 30’ and it just shut off. My machine will not crank if the switch is not in the run position.

I wonder if you have a faulty or open switch then. Based on what I saw (below but a 018) it should crank...but again I cant try mine right now.

 

[Beech123]

I wonder if you have a faulty or open switch then. Based on what I saw (below but a 018) it should crank...but again I cant try mine right now.

Thanks for the help. I have used that switch several times. In the past to keep my young son from starting the machine. It has never cranked when switch was pulled

 

[Beech123]

Thanks for the help. I have used that switch several times. In the past to keep my young son from starting the machine. It has never cranked when switch was pulled

I have had this machine for 6 years and have been an operator for over 20. I’m very familiar with the operation and safety features, I’m just not a mechanic I do appreciate all your help, but I’m 100% certain it is not the switch. When I get into the diagnostic screen of the machine, it will actually show all the switches either in closed or open position. If you move a switch to a different position it will show change either to open or closed on the screen. I have checked the switch verses that as well