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
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
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
Engine is very strong sounding and running, would really doubt it engine are those unplugged connectors in my pictures from the electronic throttle?
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
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
Thank you
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.
Sorry, when I say top I actually mean the closest one to you when you open the cover.
I’m not seeing the screen on mine
I am trying to figure out what connectors these are on the solenoid so I can make my own solenoid harness tester
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.
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
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.
@shelbyk7 , I PM'd you.
I have tried testing solenoids with 12v direct power and did not get any improvement in function this was suggested by MG2361
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
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
Agreed M
So tomorrow is going to be 70*F and I plan to test as many things as possible How does one go about testing pressures on the pump? Where are the test port locations ? I purchased a kit but cannot find info online at all about where to test
Did you check the F4 (1A), F7 (1A), F8 (5A) and F9 (5A) fuses There is a port just above the output hose of the pump that a gauge can be connected to. You will have to acquire a fitting to put in place of the plug. If you hotwired the one farthest from the engine only and it still stalled, then yes it is possible that the solenoid valve assembly could have issues. You could try swapping the whole assemblies to see if that changes anything. Unfortunately without being there to hear it (to determine if it is engine power or a hydraulic issue) and without diagnostic equipment so we can clear the codes and see what comes back, we are only shooting in the dark. Try disconnecting the battery for 10 minutes, then connect it and check codes. See if they are gone. I am not sure on those units if a battery disconnect will clear codes. Maybe you could post a short video of the machine and showing how it stalls.
Fuses checked out okay, I will take a video of it stalling and check codes again
Also, can anyone tell me how many of the banjo fuel strainers there are? And where they are located?
There should be a strainer in the outlet of the fuel thank and one in the fuel priming pump inlet. 2 questions, has your machine sat for a while prior to you buying it? Do you have bio blend fuel? The reason I ask is I have borrowed a mates tractor and it started doing exactly as you described with your machine. The tractors fuel system was full of snot which I've cleaned out and now is running normally. Diesel here is 4% biofuel and no choice.
No strainers, have a rebuild kit for lift pump coming in what do most people do about the water separator? My bowl is old and unable to see water or fuel and it’s not cleaning up. Am I better to go another direction as far as different separator or should I just get a new bowl (if they sell them)? the oem separator is only a separator and not a combination of a filter and separator , right? If so, is it beneficial to add an additional filter for fuel system? Something like the racor?
Update had some things come up and wasn’t able to work on it much , however the past couple weeks I have been List of completed- All new hyd fluid, drained cylinders as well best I could (old fluid was very nasty and had tiny bits of rubber from what I believe is the cylinder seals that are leaking) -All new filters, fuel, pilot and full flow - rebuilt lift pump - new seals in swing motor -bled the pumps started it up first time since I had gotten it and it was running very slow. Like a snail and no power , this surprised me as the last time the issues I had were completely different, normal speed hyd but it would stall under load. so I shut it off and gave it some thought and I had forgotten that at some point I switched the solenoids around on the pump, so I switched them back around and boom, back to the way it was acting, maybe a little better now with clean filters and fluid my question is this, with the drastic change in solenoid swapping, that confirms that one of them is bad, correct? move read that the seals go bad and allow fluid to the coil? Can these be re sealed or does it need a new one?
usually what happens with these from what we've come across is the DP sensor/angle sensor or pump solenoid fails. This causes excessive hydraulic oil temp which cooks the seals usually. So if the or rings are solid then it could be what happens. Theres a small control valve with 6 solenoids, make sure you replace the o rings on them as any bypass on those seals will cause a myriad of issues that just don't make sense!. But do check the fuses first to make sure they are all good. I have a manual for this is you want.
also check the throttle motor cable as sometimes the exhaust muffler leaks and the heat melts inner sleeve of the cable and could be that the cable is sticking etc or not throttling up the engine as needed. just check if it is moving freely especially if the muffler is leaking gas onto the cable.
usually what happens with these from what we've come across is the DP sensor/angle sensor or pump solenoid fails. This causes excessive hydraulic oil temp which cooks the seals usually. So if the or rings are solid then it could be what happens. Theres a small control valve with 6 solenoids, make sure you replace the o rings on them as any bypass on those seals will cause a myriad of issues that just don't make sense!. But do check the fuses first to make sure they are all good. I have a manual for this is you want.
Looking to gain a good understanding of how all these controller work to be able to do controller repair.