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  1. #1
    Join Date
    Aug 2012
    Location
    Hermiston Oregon
    Posts
    247

    Default miller bobcat problem need help

    1st problem I keep popping my breakers both 220 & 120. 220 is more sensitive.
    Do I need to replace the breakers from my understanding they become weaker the more they pop.

    2nd problem after running longer than 1hr the machine acts up and begins to choke like its out of fuel. I shut it off a few minutes and starts right up. But problem continues after that first hour.
    .
    Miller Bobcat 225NT onan
    Millermatic 211
    Spoolmate 100
    (Retapped to fit regular mig tips)
    Work better & less parts to stock.
    Miller 130xp
    T/A Dragster 85 (portability 11 pounds)
    Oxygen/Acetylene torch set 50'
    2. 4-1/2" grinders
    1. 9" grinder
    14" Makita chop saw
    1/2" Aircat impact gun 900#

  2. #2
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,725

    Default

    You know there are various models of the Bobcat, sure would be easy to lookup with say a ......SERIAL #

  3. #3
    Join Date
    Aug 2012
    Location
    Hermiston Oregon
    Posts
    247

    Default

    Serial# kj085052
    Bobcat 225 nt
    1100 hrs
    Last edited by eecervantes83; 08-04-2014 at 11:33 AM.
    .
    Miller Bobcat 225NT onan
    Millermatic 211
    Spoolmate 100
    (Retapped to fit regular mig tips)
    Work better & less parts to stock.
    Miller 130xp
    T/A Dragster 85 (portability 11 pounds)
    Oxygen/Acetylene torch set 50'
    2. 4-1/2" grinders
    1. 9" grinder
    14" Makita chop saw
    1/2" Aircat impact gun 900#

  4. #4
    Join Date
    Jun 2011
    Location
    New Zealand
    Posts
    34

    Default Oil level

    I have the same machine. I have had the cutting out problem, it was caused by the oil level being low and certain conditions caused the low oil cut out to shut it down. If the oil is up on the dip stick it will be something else. My breakers have not caused any problems.

    I hope this helps

    Nick

  5. #5
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,725

    Default

    Well set your engine RPM it around the 62.5hz mark, (Probable set wayyyy too low at present) Then you will stop popping breakers, as volts drop amps increase, thus popping breakers.

    As for sluggish, its likely that your not using the correct oil. These small engines and especially the onan needs an oil with Zinc in it. So a couple liters of 10-40 motorcyle oil will smarten the engine up, or quakerstate "DEFY" in a 10-40

    Try this easy stuff first before we continue on.

    So get yourself a meter that reads HZ, stuff the probles into your 120 Vac terminals, loosen off the 13mm lock nut right side engine just above the valve cover and tighten the 8mm bolt untill the meter reads around the 62.5hz mark high idle no load.

  6. #6
    Join Date
    Apr 2009
    Location
    Oswego IL
    Posts
    639

    Default change oil and filter, replace inline filter, change spark plugs....then

    If the above does not fix machine, i would bet you have a bad coil which is dropping a cylinder. Easiest way to tell is to run machine when it starts to die, use a temp gun and shoot the exhaust ports see if one is colder by a lot. Replace the igntion coil then.
    Kevin
    XMT 304
    Miller Spectrum 625
    Miller 30a spool gun
    S22a
    Miller Legend 302
    Lincoln LN25
    Ford f450 Maintainer Srv Truck

  7. #7
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,725

    Default

    Unlikely as the onan only has 1 coil, so both sides would be weak, unlike the Kohler which has 2 coils. It is a possibility though that the vacumn operated fuel pump is weak, or is loosing vacumn

  8. #8
    Join Date
    Aug 2012
    Location
    Hermiston Oregon
    Posts
    247

    Default

    I'm going to follow the advice posted and keep you informed of the outcome. Thanks for the help
    .
    Miller Bobcat 225NT onan
    Millermatic 211
    Spoolmate 100
    (Retapped to fit regular mig tips)
    Work better & less parts to stock.
    Miller 130xp
    T/A Dragster 85 (portability 11 pounds)
    Oxygen/Acetylene torch set 50'
    2. 4-1/2" grinders
    1. 9" grinder
    14" Makita chop saw
    1/2" Aircat impact gun 900#

  9. #9
    Join Date
    Apr 2009
    Location
    Oswego IL
    Posts
    639

    Default well..

    Quote Originally Posted by cruizer View Post
    Unlikely as the onan only has 1 coil, so both sides would be weak, unlike the Kohler which has 2 coils. It is a possibility though that the vacumn operated fuel pump is weak, or is loosing vacumn

    i have replaced countless coils on onans. You are correct that it is one coil. However when weak they fire one cylinder with the least resistance. This engine is giving all the symtoms of a bad coil. Fuel pumps are either good or bad. I have never seen a pump work for a hour then quit.
    kevin
    XMT 304
    Miller Spectrum 625
    Miller 30a spool gun
    S22a
    Miller Legend 302
    Lincoln LN25
    Ford f450 Maintainer Srv Truck

  10. #10
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,725

    Default

    Just thinkin that the unit gets hotter ( and it will if there is zero zinc in the oil), that he is loosing compression and thus vacumn pressure to the pump. Engine goes sluggish (cause its freaking hot) but doesn't up and die.

    These engines run amazingly cooler with the recommended zinc content. So motorcycle oil is best or Quakerstate Defy are pretty much the only oils with enough Content. As well as Diesel oil. Most guys tend to run straight automotive oil, and wonder why thier engines crash at under 2500hrs. My customers are still running at hrs exceeding 10,000. Hmmm, wonder why.

    If I put automotive oil in my $10K EVO engine, it would bake itself pretty darn fast, same goes for ALL air cooled engines.
    Last edited by cruizer; 08-05-2014 at 10:02 AM.

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