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312 throttle problem

Discussion in 'Excavators' started by Jam, Dec 1, 2010.

  1. Jam

    Jam Well-Known Member

    Joined:
    Nov 11, 2009
    Messages:
    201
    Occupation:
    Building contractor
    Location:
    Cork, Ireland
    hi guys... I started my 312bl this morning and the aec control dial only started to increase the engine revs from position 5 upwards but position 10 only had the engine doing around 1500rpm. I adjusted the throttle cable to compensate for this temporally and its running away fine but now position 8 is full revs with position 9 & 10 doing nothing.The auto idle does not work now either but the idle down button on the joystick does. The manual controls work perfectly. Is there any calibration technic to try or any other suggestions appreciated.
     
  2. Boiled Owl

    Boiled Owl Well-Known Member

    Joined:
    Nov 4, 2010
    Messages:
    78
    Location:
    Western Indiana
    I'm no authority here! While working on my 320 throttle problems, the Auto Idle down (AEC) didn't work because the speed sensor on the flywheel was bad.
     
  3. -3Doc

    -3Doc Well-Known Member

    Joined:
    Jul 29, 2009
    Messages:
    119
    Occupation:
    Ticketed HD Mechanic
    Location:
    British Columbia
    There is a procedure for resetting the positions of the throttle motor, it is called the engine learning step and is done through the computer pad in the cab, I have done it a few times on the 315 but can't remember the steps. do you have access to a manual? It is quite easy to do if you follow the steps.The problem I found on the machine I work on is the cable came loose on the engine end and once the computer looses its way it goes into a limp mode until you can fix the problem.Hope this helps. If you can't find a manual I may still have the pages for the 315 (might have to do some digging) good luck.:)
     
  4. catmtl

    catmtl Member

    Joined:
    Oct 2, 2009
    Messages:
    15
    Location:
    Tacoma, WA
    I had a simular problem several years back on my 312BL, Turn out to be the governor control motor. the control cable passes through a metal shield, and if you have a ground cable problem the control cable will act as a ground and fry the gov control.
     
  5. collins_br

    collins_br Well-Known Member

    Joined:
    Dec 3, 2010
    Messages:
    55
    Location:
    Ireland
    Hi guys, sorry to just jump in here but the admin won't let me creat a new tread yet.
    I have a 2008 323D C6.4, which is very very difficult to start in cold weather. To date i have replaced air temp sensor, fuel pressure sensor on common rail, transfer pump (attached to rear of main pump) all rubber hoses and checked loads more. It will crank and waybe start for a second, but then stop again and this can go on for 25 mins. When started and up to temp, it runs fine. Main dealer only interested if they get an open cheque book!!!.All help welcome.
     
  6. CRAFT

    CRAFT Senior Member

    Joined:
    Jan 6, 2010
    Messages:
    929
    Occupation:
    30 yrs Owner/Operator
    Location:
    100 M H,BC,Canada
    I had a simular problem with my 312A model ... but the govenor failure was due to the rad not cooling out the engine enough ... it caused the engine compartment to have way to much excessive heat build-up, eventually melting the sleaves where the throttle cables slide thru and binding up and then seizing up the cables and burning out the govenor motor
    Got the new pricey govenor motor c/w cables (the only way you can buy it) and installing it ..... then the Cat product support guy came by and did as mentioned, went into the program mode and set it up ..... next time it heated up I could tell that the throttle became not very responsive (kinda sluggish) ... when I shut it down the damn cables seized again .....I was lucky tho and was able to free them up .... that's when we found out after alot of farting around that it was the rad and not : the thermostat, not the sensor, not the rad cap, not the gauge, not the water pump... ect.
    Finally replaced the pricey rad (which I must have been the only guy to ever replace a 312 rad, so told) which had to be ordered and shipped from the back east warehouse (extra cost to ship) .... but after all of this its been 4yrs now and it works flawlessly .... wouldn't trade the 'ol Cat for nutt'n cept for maybe a newer 314CL w/air .....LOL ...... JMLS .....:drinkup
     
  7. CRAFT

    CRAFT Senior Member

    Joined:
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    929
    Occupation:
    30 yrs Owner/Operator
    Location:
    100 M H,BC,Canada
    COLLINS_BR .... that series of Cat should not have those kinda issues for starting .... especially where you are and the temps you're subjected to.... have you ever had the valves re-set ??? ... when the valves are to tight the tolerances get tighter not allowing the engine compression to be up there .... my 320clu has been started in -30 C temps after the engine air pre-heat cycle light goes out, sure it was grunting away for a couple of mins until the hyd oil churned up (and we only use sae 10w) but the engine had no problems firing up .... just a thought ??? .....:beatsme
     
  8. Lee-online

    Lee-online Senior Member

    Joined:
    Jan 16, 2010
    Messages:
    1,023
    Location:
    In a van, down by the river
    How many hours are on the machine? do the fuel filters get pre filled when changed? Are you using cat fuel filters? what kind of smoke is it making, if any?
    You really need Cat ET to check out the engine. It will only take a few minutes to see what is going on.
     
  9. collins_br

    collins_br Well-Known Member

    Joined:
    Dec 3, 2010
    Messages:
    55
    Location:
    Ireland
    Thanks for the replies, 3800hrs , never checked valves, is this something that would normally be done as this is my 4th 320 and never had to before and is it done the same as older engines ie feeler gauge & spanner ? I always use cat filters and the system bleeds out fine, all 3 filters have been changed several times in trying to fix this. Its not even than cold -2C to 5C etc. I'm realy stuck here so any suggestions welcome. :Banghead
     
  10. collins_br

    collins_br Well-Known Member

    Joined:
    Dec 3, 2010
    Messages:
    55
    Location:
    Ireland
    PS. I have Cat ET, Its not telling me a whole lot. It gives me a low common rail fuel alarm sometimes, but it seems only be out by a very small amount, that said i'm not very experienced in using it.:beatsme
     
  11. ke6gwf

    ke6gwf Well-Known Member

    Joined:
    Jul 1, 2010
    Messages:
    81
    Location:
    Napa Valley CA
    :eek::Banghead:eek::Banghead:eek:

    Pre-filling bad!
    I have heard it both ways over the years, but the bad side has a very compelling argument. (and is supported by the people that build the machines and claim to know something about them)

    When you pre-fill a filter, all that fuel you are putting in is unfiltered, and chances are it is coming from a nozzle or a can (or scary thought, but it was the way I was first shown many moons ago, emptied out of the old filter :eek: ), or some source that is likely to have way too much crud/dust in it.

    When you think of the tolerances in an injector pump or a nozzle and think what that dust will do as it passes through the system, you understand why the manufacturers say not to pre-fill.
    I know, it makes bleeding a little harder, but it also makes engine life a little longer!

    Just say NO!

    Ben~
     
  12. ke6gwf

    ke6gwf Well-Known Member

    Joined:
    Jul 1, 2010
    Messages:
    81
    Location:
    Napa Valley CA
    323D cold start problem

    How is the pressure set on the Rail? Electronic control or mechanical regulator?
    If you replaced the sensor and the new one is saying the pressure is dropping, I would be looking at something mechanical in the pressure system.
    I have run into engines that had a regulate-out setup were the reg was sticking and it would allow the pressure to drop long enough to cause problems.
    When the engine is cold, it wouldn't take much of a drop to reduce atomization enough to lose your fire. I don't know if you can stick a gauge on there, or if there are too many spikes to get a usable reading, but I would take a good look at pressure drops and possible causes. I would look at the reg first because that's a lot cheaper than a pump!


    Ben~
     
  13. DirtHauler

    DirtHauler Senior Member

    Joined:
    Nov 26, 2007
    Messages:
    507
    Occupation:
    Heavy Highway Dirt Hauler
    Location:
    Seattle WA
    did you check to make sure no one put it in finish grading mode? I don't know about that particular machine but a kobelco i ran once had a setting for fine manuvering that would limit engine rpms and make for smoother movements. I think the idle down was disabled in this mode as well.
     
  14. collins_br

    collins_br Well-Known Member

    Joined:
    Dec 3, 2010
    Messages:
    55
    Location:
    Ireland
    I took another look with the ET and found that the fuel rail pressure is all over the place. At trottle position 1 the desired is 35000kpa but it varies from 25000 to 45000 also fuel rate and boost pressure are bringing up alarms. Could this be the pump? if so how big a job is it to change, timing etc.Thanks in advance Brendan
     
  15. Lee-online

    Lee-online Senior Member

    Joined:
    Jan 16, 2010
    Messages:
    1,023
    Location:
    In a van, down by the river
    The first and easiest thing to change if the fuel pressure is wrong or erratic is the high pressure relief valve in the fuel manifold. These have been updated so get the newer one if you replace it.
    The desired and actual pressures on a good engine are almost exactly the same.
    Replacing the pump is a little difficult on a 6.4/4.4 because the way it is set up. The pump needs timed to the drive gear at TDC. This is done through small access covers on the front cover. Then its a matter of removing it. Remember, any high pressure fuel line that is removed must be replace with a new one.
    I have done pumps on all the common rail engines and the 6.4/4.4 in the excavators are the hardest.
     
  16. collins_br

    collins_br Well-Known Member

    Joined:
    Dec 3, 2010
    Messages:
    55
    Location:
    Ireland
    Thanks Lee. I remove that valve this morning and it looks fine. I added 2 extra washers to add more compression to the spring but it made no difference so i removed them again. Any more suggestions. More detail in replacing the pump would be seriously appreciated. Thanks Brendan.
     
  17. Boiled Owl

    Boiled Owl Well-Known Member

    Joined:
    Nov 4, 2010
    Messages:
    78
    Location:
    Western Indiana
    Wonder if JAM ever solved HIS problem???
     
  18. Jam

    Jam Well-Known Member

    Joined:
    Nov 11, 2009
    Messages:
    201
    Occupation:
    Building contractor
    Location:
    Cork, Ireland
    Hey there... I havent got around to looking any further yet because we are busy enough with her at the moment. With the cable adjusted it is throttling away up perfect but iv no auto idle so just using the righthand joystick button to idle her down. Iv no repair manual unfortunitly so when i get her back to base il be asking more question if ye dont mind :)
     
  19. Jam

    Jam Well-Known Member

    Joined:
    Nov 11, 2009
    Messages:
    201
    Occupation:
    Building contractor
    Location:
    Cork, Ireland
    Had the digger back to the workshop for an oil change today so took out the speed sensor for a look. It was covered in small starter fillings so cleaned it down. I checked the resistance which was 130ohms. Screwed it back in and thank god auto idle is back working again. My only question is there a calibration that can be done to set things up properly again because she is idling down to about 1000rpm in the auto instead of 1300rpm? any input appreciated