Hi, I brought two excavators at a auction, one of them being a Hitachi that i am getting ready now. Both machines wont rev up, the other one a sumitomo said on the electric display that there was an electrical problem. The machines were from different vendors so i am guessing its not a coincidence and that someone at the auction tampered with something. I cant find anything wrong with them, i had an auto electrician out and he couldnt see anything wrong. In the sumitomo nothing electrical worked(lights wipers ect) but on the Hitachi everything else works fine, its just the revs. Any Ideas? Cheers
on the hitachi did you change the fuel filter had that problem before all so i believe there a small screen inside the banjo bolt that connects the fuel line to the filter housing check that too
First thing I would do is try to get the RPM's up manually. Disconnect the electric motor and try to move governor lever. Once you find it is not in the fuel pump are you getting current to the throttle dial and the throttle motor. If that has what my techs refered to as a bag motor it commonly gets full of water and will rust up.
Check the Batteries Had this problem once before, One battery was down on charge and didnt have enough power to throttle up! Common enough if a machine has been sitting for while! Failing that check the power from the alternator have seen strange eletric problems from bad alternators!
Hi, Yes i can rev it up manually, and also the batteries are good. I have charged them since getting it. Cheers, Nick
Also should note that i have taken the throttle motor off and it works, so it is something between the switch and motor(mechanically its perfect)
Hi, Common problem with Zaxis machines is the EC sensor failure on step motor and throttle dial potentiometer on dash. Do you have access to DRZX? If so this will tell you straight away. Something as silly as a seized throttle cable on step motor as per previous message regards disconnecting stepmotor and pull cable. If cable is ok the engine will rev.
Had two 160's with that problem. You could grab the knob and wiggle it and they would rev up. You have to buy the harness with all the switches. Has anyone found just a replacement switch? It's a Cosmos Tokyo - RVQ24YN02HT
You can now purchase just the switch on its own p/n: 4609249 Something else worth checking - is the engine learning switch in the middle position. If someone has knocked it into learning position or service position you loose your throttle.
That's good to know- thank you!
Attached is the engine learning switch and procedure.
Hi, Is there any way to test the EC Sensor without a DRZX? The auto electrician confirmed that the throttle dial is fine and working. The cable is fine because if i take off the step motor and pull the cable it revs up and is fine. Where do i find the learn switch? the attached photo is a bit blury and i cant reconise where it is. Cheers, Nick
Hey Nick, Drop me an e-mail [email protected] and I will send you all the info you need to troubleshoot. Cheers
Awsome dieselmax. This is what makes this site so great.:thumbsup
Hi, A big thank you to dieselmax, we have been sending emails back and forth and he was a great help. turns out there was only 3.7v going to the step motor from the computer. Put second hand step motor in and it didn’t change, put second hand MC Computer and volts went back up to 4.9 and everything is ok, although the old step motor still doesn’t work so it may have been damaged from low voltage. Thanks for all the replies, Nick
I'm a new member here and I haven't been authenticated so I cannot start a new thread and hope that my post is relevant to this one.(Hitachi Zaxis ZX130 Wont Rev Up). I have a 1994 EX100-3 that has the EC (Electronic Control) with no fuel to the injectors. This issue is not the common problem to Hitachi Excavators of the clogged fuel filter, but is likely caused by an electrical/circuit board/potentiometer/connection. The stepping motor, when ignition key is in the run position makes a ca-chunk sound and the motor seems to be fighting for a position that it can work with but cannot find it. The throttle position light goes to Power and will not set to idle, unless I disconnect one of the two leads to the stepping motor. It seems that there is a fuel shut off linkage that connects through what may be a bag motor as referred to above. I have had most of the circuit boards opened for inspection, I did not clean all of the connections though. Issue started when I loaned out the machine to the neighbor and he had an operator who surely ran it harder than I do. Is there a computer connection to troubleshoot error codes, or what is the factory guidelines for troubleshooting? Any help is much appreciated! I have checked fuel filters, air in system, fuel fed plunger up, feed pump strainer, and this issue is definitely involving the stepping motor. B
Hi Brain you have EX100-3 right?What is the serial number .What engine is in your excavtoer model and serial number.I will try to look it up in my service manual files on my laptop.
Serial Number of Hitachi with stepping motor issue rt, the Hitachi EX100-3 is serial number 35845, a 1994 with about 3200 hours, Isuzu 4BD1 Engine, orange in color I spoke with the dealer and he assured me that I wouldn't want to just start buying parts for it, otherwise, he thought the stepping motor was bad and he suggested that I note the throttle position with the key in the run position and in the off position. He said the diagnostic tools could run some money.
a DREX will save you plenty of time and probably money. After many issues with cat, komatsu and hitachi i have come to the conclusion it is much cheaper and faster to just get them out to fix it. Previsouly i have got generic mechanics out or googled the question. Nick
I had the "Engine Stop Motor" go bad on my EX400LC-3 a while back and it would not let the engine start. Shut the machine off fine one night and the next morning the machine would start and run for a second or two and then quit. If you held the key in the start position the engine would start and then shut off and then crank and start again and then shut off just like it was starving for fuel. The fuel lever was open just enough to allow a little bit of fuel in to run when you first turned the key and started the machine but not enough to keep it running. I chased the fuel lines and replaced the filters thinking it had a clog somewhere and I think I even ordered a fuel pump. (Which I still have in the box and of course now I will never have to worry about the fuel pump ever going bad since I have purchased one and have it on the self, LOL) The Engine Stop Motor on the EX400 is located on top of the bell housing or pump transmission, it is wrapped in a blueish colored bag and has a cable running to the injection pump, not sure if the EX100 has the same set up or not. The easiest way to check to see if the motor is working it is have someone cycle the key and see if the cable moves the arm on the pump. The other cable on the injection pump is for the throttle and goes to the EC motor. If your cable for your fuel shut off is not moving disconnect it, move the lever and try starting the machine. It was not hard for me to tell the engine stop motor was bad it had a burnt smell and the bag was actually burned in one spot where it got really hot. There is a fuse that powers the motor that you will also want to check. If the fuse blows as soon as you replace it I would suspect your motor is bad.
Brain try disconnecting stepping motor lever were the cable hooks up .Have some crank it while you manually trottle it .Cable could be broken going tothe injection pump. Also make lever on injection pump is free and not stuck. ED
EX100-3 Brian If you don't have fuel to the injectors your stop motor could be a problem also. Just disconnect it from the fuel pump. The stop motor only goes to fuel "on" when cranking. On a good running stepping motor on -2 or -3 ex machines you can disconnect the motor with no operational problems. The stepping motor will go to very low fuel when you key off and the engine will shut down. What you are loosing when you disconnect it is the emergency shut down. It sounds like your stepping motor is also giving you problems. If you disconnect the stop motor then unplug the stepping motor and manually put the throttle T linkage to a position that you can screw the long 13mm head bolt into the T linkage you should be at idle. Try starting it. If it starts then you have should have no fuel issues. One thing to remember is that in this condition you will not be able to shut the engine off with the key. You will have to pull the fuel stop lever on the governor or pull the bolt out and move it to low fuel position. If it starts then you have to go to step 2. Problems electrically ec angle sensor even a kinked or stiff throttle cable will give you problems.
The Stepping motor cable was seizeid inside the sheath so that the motor could not move the throttle. What worked was to remove the sheathing cable from the inner cable so that only either end was attached to brackets which worked Fine. It worked fine for a half of a year and now the machine is symptomatic of no fuel, where I have good glow plugs, air, compression and fuel supply. when cracking the injectors. The machine will cough when supplying propane to the intake. I will investigate the 'Bag Motor' further, although I have tied back the cutoff cable 'away' from the injector pump, which did not This is now an old thread, but if anyone hits this page and has ideas, please let me know! Brian
Fuse The other 'not starting issue' was due to a blown fuse for the circuit that goes to the 'bag motor' or stop motor. The machine starts right up. Thanks Ken, Ed, Nick, all
you can test a stepping motor by using a ohm meter. There are two coils in it. The rsistance in both of them should match each other. I think 5.7 ohms apeace but i"m not sure on that. Does this engine run if you run the govenor arm by hand?
ayuda por favor ... Necesito ayuda con un hitachi zx 120 ... no da rpm y no tengo el diagrama esquemático de la máquina ... por favor, si me lo pueden dar, estaría muy agradecido ... gracias