Onan generator won't run

Discussion in 'Tech/Mech General' started by Bryan, May 11, 2011.

  1. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342
    Hi,

    I've got a problem with my onan generator on my RV (it's a 4ky)

    A few months ago (when I last wanted to use it) it wouldn't start. It wasn't too important at the time so I left it, suspecting low oil.

    I checked the oil a few weeks ago and it was indeed low.

    I've just bought some oil and went to add it but the dipstick shows adequate oil now [​IMG]

    But whilst the generator will crank over AND START and run whilst I hold the generator start switch, as soon as I let go it stops. I've tried holdiong the start switch for longer but after 16 seconds it stops running and flashes the code for over crank.

    I need to get it going in time for Stratford [​IMG]

    Any ideas?

    (I had a new carb and control board installed last year at cummins, btw)

    Bryan
     
  2. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,069
    Likes Received:
    13,677
    Location:
    Heavan
    Sounds odd regarding the oil Bryan,
    May I suggest a complete drainage of oil and filters, and then refill to correct levels to ensure that area is correct.
     
  3. Jim

    Jim Ringleader

    Joined:
    Jul 19, 2007
    Messages:
    25,845
    Likes Received:
    76,162
    Location:
    Sutton on Sea
    How much fuel do you have in your main fuel tank? Many gennies won't run when the gauge falls to below a third or so.
     
    • Like Like x 1
  4. dazzer

    dazzer Read Only Funster

    Joined:
    Jul 30, 2007
    Messages:
    1,698
    Likes Received:
    99
    Location:
    In my house
    Could be your change over box thats gone tits up. Happened to mine when i first shipped it from USA. The change over box is the clever bit of electronic wizardry that prevents you hooking up to shore power and running the genny at the same time.
     
  5. Dodgey

    Dodgey Funster

    Joined:
    Oct 15, 2007
    Messages:
    1,603
    Likes Received:
    227
    Location:
    Gone RVing
    Risking a useless post here, someone else had this issue recently but I can't think for the life of me who, when or what the thread was about and perhaps more importantly what the problem was. :Blush:

    Try a search maybe and see if you can unearth?
     
  6. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342

    Over half a tank :thumb:


    Don't think I have one. If both hookup and genny on then I trip mcb's all over the place :Rofl1::Wink::thumb:




    Thanks for the ideas guy's ...keep 'em coming
     
  7. slobadoberbob

    slobadoberbob Read Only Funster

    Joined:
    Jun 1, 2009
    Messages:
    6,159
    Likes Received:
    1,970
    Location:
    Kent, garden of England
    this genny does not have an oil filter

    The 4 kw Onion microlite does not have an oil filter.

    Have put a few suggestions Brian on the RVOC site .. your fuel was very rich on the genny when you were parked up beside me at Lincoln.. last time I suspect you used it.

    points? plugs and as jim said..enough fuel in the main tank?

    Bob:thumb:
     
  8. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342
    Definately enough fuel in the tank.

    I have just checked the generator output whilst cranking/runnning at it is only 30-40v AC not 110/120v...
     
  9. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,069
    Likes Received:
    13,677
    Location:
    Heavan
    Quite right, it is splash lubricated, however perhaps you ought add correct oil to your bottom line? or is my input not worthy?

    does yours have fuel and Air filter Bryan? could they also be creating a problem? especially if the lawyers assessment of running too rich is an issue,
     
  10. artona

    artona

    Joined:
    Jul 31, 2007
    Messages:
    1,480
    Likes Received:
    690
    Location:
    Europe
    there is a cut out switch hiding away somewhere that when the oil got low tripped, maybe
     
  11. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342
    I don't think it's an oil issue, wouldn't it fail to run/start at all? I have added oil to make sure it is full just in case.

    Not sure if it's running too rich or not, but again, why would that cause it to not run? Surely it would run, just run too rich (as it may have done at Lincoln)?

    I think the voltage output is too low and that may be stopping the generator from running as IIRC it needs the 110v to keep running.




    Any more thoughts/idea anyone?:BigGrin:
     
  12. Dodgey

    Dodgey Funster

    Joined:
    Oct 15, 2007
    Messages:
    1,603
    Likes Received:
    227
    Location:
    Gone RVing
    To rich and it wont run, there is a little tolerance but the fuel air mixture needs to be right. Now, you say it runs while you hold the button but is it really running, ie is it just trying to run but due to fuel air mixture being to rich it isn't actually, it's just by vertue of the cranking it sounds like it?

    Was it cold the last time it ran? If it was there could be something to the rich suggestion as cold starting the mixture is richened to get it to start (choke in old language) and weakens to an optimum mixture as it warms so the cold could have allowed it to run, all be it rich.

    One option try a start the remove the plug. If it's wet (pertol) it could be a clue, though not an absolute. If you've got the manual you may be able to weaken the mixture a little to try but go carefully or better still see if you can identify the choke system and remove and see if it'll start, that would at least identify if you're in the right area for the fault.

    Bear in mind, a weak mixture can damage the engine so disconnecting the chole shouldn't have any adverse effect but if you start with the mixture you do need to take advice re proper set up (Duncan?).
     
  13. Dodgey

    Dodgey Funster

    Joined:
    Oct 15, 2007
    Messages:
    1,603
    Likes Received:
    227
    Location:
    Gone RVing
    Choke options, remove air cleaner and there could be a butterfly valve right on the front of the carb, there will be one at the back to, but the front is the choke. Closed for rich/cold start, open for normal running. The other option is some for of petrol enrichment, look around the jet/petrol in part of the carb for a moving section, the butterfly is the more common but on the Onan's I don't know frankly.
     
  14. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    From the Onan trouble shooting guide:

    Q. Why does my generator start and then shut down as soon as the start switch is released?

    A. Most models require both oil pressure and AC voltage from the generator to keep running. A lack of AC voltage can be caused by a variety of problems involving the control board, regulator, generator and wiring.

    A stuck oil pressure switch can also cause this symptom. The interaction between the various components of the system can be confusing during troubleshooting.

    Use the Troubleshooting Guide to isolate the problem.

    http://www.flightsystems.com/pdf/onanrvtshootgd608.pdf

    check the easy things first:

    * Oil level
    * Blown Fuse or tripped MCB
    * Dirty or broken cable connections
    * Damp in control unit
    * Damp in multi plugs
     
    • Like Like x 1
  15. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342
    Thanks SJL

    As I only have 43 volts output from the genny I suspect it is this low voltage that is causing the problem.

    As this can be caused by many things (including the control board which was replaced last July by Onan) I think I'd best take it back there for a look.

    Thanks all for your suggestions :thumb:
     
    • Like Like x 1
  16. Sundowners

    Sundowners Funster Life Member

    Joined:
    Oct 30, 2007
    Messages:
    2,346
    Likes Received:
    1,404
    Location:
    Suffolk
    Hi Bryan
    The symptons you have are the same as ours---------we had it checked out by a company that only does generators--------their verdict----it IS part of the safety system-------in our case, it is the board that controls the Htz (he assured us) he couldn't fit the board as it was Friday afternoon-------he was going fishing------so we brought the board back with us, and have to remove genny to fit it---not yet had the time/weather/inspiration all at the same time !!!!!!!! so don't yet know if we can get it going !!!!!
    Good luck with yours
    Nigel & Pamala
    BTW-------hope you are still in the South--------well away from the earthquake !!!!!!!!!!!!!
     
  17. Bryan

    Bryan Read Only Funster

    Joined:
    Jul 19, 2007
    Messages:
    2,096
    Likes Received:
    342

    Well away, thankfully - just sat in the bar having breakfast and Suzy is reading the local paper; 8 dead it says :Sad:


    I've read that the symptoms we are suffering can be caused by a number of things - pcb being one of them. I had a/the pcb swapped last July so I've decided to let a specialist take a look when I get back.

    Bryan
     
  18. ehuplad

    ehuplad Read Only Funster

    Joined:
    Feb 9, 2009
    Messages:
    509
    Likes Received:
    93
    Location:
    North Yorkshire
    I think that is the correct decision Bryan, Have you spoken to him, Give him a ring he may be able to give you some pointers to get it going until you return.
     
Loading...

Share This Page