Starting Trouble

[garjess]

I've got a KX040-4 excavator that will only start with a shot of starting fluid. The machine runs great, doesn't smoke, and has great power but it wont start. This problem is EVERY time I start it! HOT or COLD, even if I've been running it and shut it off for a second, it wont restart without starting fluid. When I try to start it, it turns over fine, but there isn't any smoke or even a smell of fuel or exhaust from the exhaust pipe.
It's like the fuel is shut off until it is running. Is there a sensor or shutoff that would behave like this?
Thanks for any help.

 

[Russell King]

That is an odd situation that I have not heard of before.

But first, stop using the starting fluid since you will destroy the engine (if you haven’t already damaged it).

Since you have used starting fluid on it, you need to start off with checking the compression of all cylinders. I assume you will find them low but at least you will know if there is a compression problem or not.

Next you can get a test kit and see if there is combustion gas in the radiator fluid which indicates if there is a head problem with gasket or cracked.

Since you say there is NO fuel smell out of the exhaust when trying to start it, have you investigated the flow of fuel and how it is moved to the injection pump? I assume there is some fuel shut down and the engine stops running when the key is turned off. That is usually a solenoid that either holds fuel on when running or shuts fuel off until the engine dies and then returns to “on”.

How long have you had the excavator and how long has this been going on? Is it a sudden change or gradual change? Did it ever start correctly without the starter fluid?

 

[garjess]

Odd to say the least. I've been around diesels my whole life and I've never seen one that wouldn't crank after it was warmed up.
The machine is new to me. I was told the glow plugs didn't work and it needs a shot to get started. No big deal, easy fix. I didn't try restarting it after it had run some. Why would I? Its a diesel, of course it will restart, right. I fixed the glow plugs and then discovered this.
I'm not too worried about compression. It runs perfect, and it doesn't smoke at all. It doesn't smoke at all, including when trying to start it. I've seen diesels that were completely worn out and they puffed smoke when trying to start.
Something has the fuel shut off until its running. That sentence doesn't make any sense to me but I can't describe it any differently.
I haven't dug into the fuel system yet, I was hoping for a comment from someone who has had this problem. Russel, I would also assume there is a fuel shut off that closes and shuts the machine down, but what on earth would cause it not to open until the motor is spinning on ether.

 

[#40Fan]

How many hours on the machine?

Since it is a common rail injected engine, it won't have a fuel shut off solenoid like older engines.

I'm sure there is a test for fuel return rates that would tell you a lot about the injectors health, but I'd start with getting it scanned at a dealer and look at the commanded versus actual fuel rail pressure.

 

[Russell King]

Kubota has some interesting ways of controlling the flow of fuel. Sometimes there is a control system (computer), sometimes it is a simpler control box and sometimes it is simply an energized wire to the solenoid. I guess it could also be something going on with some fuel pump being out or weak but the injection pump being strong enough when running??

Is there a way to get to the injection pump easily and see if there is fuel flow when the key is off (gravity flow?) or if there is a lift pump? Do you have a work shop manual or wiring diagram? I would try to rig up some gravity fuel flow directly to the injector pump and see if you can manually open the shutdown solenoid. There may be some mechanical shutdown lever that may help.

I was assuming this is an older model but looked and see that it is the current model. Is there no warranty left? How old is it and is it common rail high pressure injection? I think you will have to get a dealer service shop to hook up a diagnostic system to figure it out!

 

[garjess]

How many hours on the machine?

Since it is a common rail injected engine, it won't have a fuel shut off solenoid like older engines.

I'm sure there is a test for fuel return rates that would tell you a lot about the injectors health, but I'd start with getting it scanned at a dealer and look at the commanded versus actual fuel rail pressure.

It's got 1400 hrs. I was hoping for a easy fix but a dealer visit is probably the next step.

 

[North Idaho Wolfman]

It's got 1400 hrs. I was hoping for a easy fix but a dealer visit is probably the next step.

I bet you do a compression test on the engine, it's going to point out the problem instantly.