Assistance with hitachi EX120-3

[shelbyk7]

I picked up a 1998 hitachi EX120-3 this weekend with it having the stalling issues

I’ve read a bunch about it but lots of them say to do different things first


This is my first excavator

what’s the best way to systematically figure out the issues? First step, 2nd etc..

i have picture of sensors unplugged in the engine bay, can anyone identify?

i have the service manual pdf that I’m printing tomorrow

does anyone have the other manuals? Operators manual specifically, not sure if there are any others

thank you for the help, I am working on it tomorrow so looking to try to get a game plan

 

[uffex]

Good day
That is a common issue with the machine - pump regulation controlled by electronics been disconnected, the power requirement will exceed what the engine can make. Some have fitted a conversion to manual it would seem that has mixed results.You could try trouble shooting the electronics if they are in good order its down to the engine.
Kind regards
Uffex

 

[timbercutter]

Is it stalling at idle or under load? I had a stalling problem before as well, it turned out to be fuel related.

Couple simple things you may want to try before you chase electronics They look like they have been unplugged for a while.

1) clean the banjo bolt at the inlet side of the water seperator they can plug up easily. Fuel filter as well could be an issue. Second, if that doesnt fix it try pulling the fitting that the bolt is connected to on the fuel line if there is little or no flow with the bolt out, I had a stalling problem before and it was debris that had been sucked out of the tank and got stuck at the fitting behind the bolt. The fuel should really pour out of the line if the tank is full. If that doesnt work I would do what the gentleman above me suggested and trouble shoot electronics. Plug in to computer and look for the trouble shooting codes

 

[shelbyk7]

Engine is very strong sounding and running, would really doubt it engine

are those unplugged connectors in my pictures from the electronic throttle?

Good day
That is a common issue with the machine - pump regulation controlled by electronics been disconnected, the power requirement will exceed what the engine can make. Some have fitted a conversion to manual it would seem that has mixed results.You could try trouble shooting the electronics if they are in good order its down to the engine.
Kind regards
Uffex

 

[shelbyk7]

But this has got to be electrical, it recovers instantly after letting off the sticks, doesn’t take several seconds to find its feet, it’s instantaneous

 

[uffex]

Good day Shelby
The valves that are disconnected are to the best of my knowledge P.W.M. control, the valves adjust according to impulse signals in much the same way as a flouresant light tube. The duration and intensity of the signals will result in the valve opening and closing, the signal is generated from a electrical control unit E.C.U. The control unit takes it's reference signal from the throttle control and selects the engine speed, should you load the hydraulics causing the engine speed to decrease below a set level the E.C.U. will compensate by the P.W.M. signal preventing the engine from stalling out. The majority of operators prefer to by-pass the system (Going manual with a kit mentioned previously) as most do not like electronics. We did some preliminary work to resolve this issue but you need to be able to measure the P.W.M. signal (oscilloscope) not many operators were keen to get involved so the investigation was put on the back burner. The common point with the issue is that of engine power, whilst I can see you are convinced otherwise my suggestion would be checkout the compression - fuel system- turbo before you condemn the electronics. Sorry if the explanation is a long one but I hope it helps in some way.
Kind regards
Uffex

 

[shelbyk7]

Thank you

 

[shelbyk7]

Also, which banjo bolt is the one that needs cleaned? These are a few I saw but didn’t seem to have a screen

 

[Garter]

Also, which banjo bolt is the one that needs cleaned? These are a few I saw but didn’t seem to have a screen

I have the same machine, it's the one on the top that feeds the fuel from the tank.

 

[Garter]

Sorry, when I say top I actually mean the closest one to you when you open the cover.

 

[shelbyk7]

I’m not seeing the screen on mine

 

[shelbyk7]

I am trying to figure out what connectors these are on the solenoid so I can make my own solenoid harness tester

 

[Tones]

Before you rush headlong into the electrics and electronics ensure the engine is performing to spec. The 2 most common causes are 1 lack of air or 2 lack of fuel. The banjo bolt with the screen is most likely to be in the inlet side of the lift/prime pump. If that checks out then as mentioned check the fuel flow from the tank, there's also a screen in there. Another thing that should be checked is the fuel line from the tank particularly all the rubber hose, it can look good externally but internally it can perish and collapse when suction is applied.
Good luck they are a great digger when performing properly.

 

[shelbyk7]

Thank, you

the previous owner installed a 12v inline pump once the original went out. For the flow test, the fuel pump need turned on, correct?

i will check out the lines

Before you rush headlong into the electrics and electronics ensure the engine is performing to spec. The 2 most common causes are 1 lack of air or 2 lack of fuel. The banjo bolt with the screen is most likely to be in the inlet side of the lift/prime pump. If that checks out then as mentioned check the fuel flow from the tank, there's also a screen in there. Another thing that should be checked is the fuel line from the tank particularly all the rubber hose, it can look good externally but internally it can perish and collapse when suction is applied.
Good luck they are a great digger when performing properly.

 

[Tones]

The original pumps are very simple and cheap to fix, about 6 buck plus postage and the systematic comes with it. They are pretty much the same pump across the range. Denso and Bosh parts are the same. One of the things with electric pumps is they can be making the correct noise and not be working, it's court me out a couple of times.
The answer to the question is yes.

 

[mg2361]

@shelbyk7, I PM'd you.

 

[shelbyk7]

I have tried testing solenoids with 12v direct power and did not get any improvement in function

this was suggested by MG2361

 

[shelbyk7]

I have read the codes from PVC and here is what I’m showing


04 - Failure of Engine Controller (EC)
10 - Open Circuit of Engine Control Sensor (EC Sensor, mounted to the throttle control motor bracket) or Wiring Harness
17 - Failure of Pump and Valve Controller
26 - Disconnected Differential Pressure Sensor (DP sensor) or wiring harness
30 - Disconnected Angle Sensor (A Sensor) and/or Wiring Harness
31 - Disconnected Temperature Sensor (T Sensor) and/or wiring harness
32 - Short Circuit of Temperature Sensor (T Sensor) and/or wiring harness

 

[uffex]

According to Hitachi data the outputs are of 5 volts, it looks as we concluded you may as well try to implement a workaround the complete electronic system go over to manual.
Kind regards
Uffex

 

[shelbyk7]

Agreed

M

According to Hitachi data the outputs are of 5 volts, it looks as we concluded you may as well try to implement a workaround the complete electronic system go over to manual.
Kind regards
Uffex