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bobcat 250 no start no spark

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  • bobcat 250 no start no spark

    hey guys. picked up a bobcat 250 cheap and am trying to get it running but have no spark..this is the onan/robin/Subaru slash cummins 20.5 ohv..lc322582..have power at the op switch ...crank it and I get power thru the switch...charge coil has 6vac cranking....resistance is about 1 ohm..which I think is low but will this cause no spark?..machine also has this little box called a stop diode?..i hate anything that says stop on it when it comes to checking for spark...does t

  • #2
    wow....cut me off mid sentence...continuing....does the sd have anything to do with the problem?...also what about the regulator rectifier?...does the charge coil supply the voltage to fire the ign coils?...any help is appreciated

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    • #3
      Wow...nothin? Pic of the stop diode

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      • #4
        Your engine is a transition engine. It says Onan but it's really a Robin. It was only made I think for 1 year until Onan switch entirely to Robin OHV. That
        said, I'm not a big fan of working on them. Anyways, There is a small relay (CR1) somewhere on the engine, in the engine circuit. Those contacts have to close to send power to the mag coil. I would start there. Also there is a diode in the engine harness (D8). It sends power to the relay coil and to the fuel solenoid in the back of the carburetor.

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        • #5
          thanks and sorry I took a bit...yea I know about the transition situation. have found different different torque specs, different valve clearance specs and who knows what else will come up as I get into this thing further..eh65 manual from robin source has diff info than the exact same onan/cummins manual for this engine..ok as for the relay and inline diode...the relay powers up when the oil press switch senses pressure and that is working. when it powers up the fuel solenoid gets power. in the diagram it looks like the relay also grounds the coils thru their primary sides thru this stop diode to shut the engine down when the ign switch is turned off. I could not see a spark so finally just grabbed a plug wire and checked it...got a spark but it is weak..barely felt it and definitely cant see it while testing with a spark tester.

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          • #6
            I'm wondering about this stop diode and whether or not it would weaken the spark?..it is the only thing between the relay and the coils

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            • #7
              Make sure your battery polarity is correct.
              I replaced the battery on my Trailblazer, the one I replaced was completely dead, somehow I got the new one installed in reverse, the engine cranked fine but would not fire, reversed the battery connections and it started up. It is a wonder it didnt blow the ignition module but it didnt.
              mike sr

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              • #8
                Pull the blower housing and disconnect the stop diode leads from the two ignition coils. If the stop diode assembly is the culprit it should fire. If it still won't then the individual coils are suspect.

                Resistance between the primary (stop) terminal and coil core should be 0-5ohms and between the secondary (plug wire) and core should be 8000-16000ohms - both +/- 20%.

                Also make sure the ignition coil-to-flywheel magnet air gap is within the .012-.020" spec.

                The charge coil is for battery recharging and resistance between the two outer terminals of its plug should be .2ohms +/-20%.
                MM200 w/spot controller and Spoolmatic 1
                Syncrowave 180 SD
                Bobcat 225G Plus LPG/NG w/14-pin*
                *Homemade Suitcase Wire Feeder
                *HF-251D-1
                *WC-1S & Spoolmatic 1
                PakMaster 100XL
                Marquette "Star Jet" 21-110
                http://www.millerwelds.com/images/sm...rolleyes.png?2

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                • #9
                  Wow...no response or update from the OP since the 15th?
                  MM200 w/spot controller and Spoolmatic 1
                  Syncrowave 180 SD
                  Bobcat 225G Plus LPG/NG w/14-pin*
                  *Homemade Suitcase Wire Feeder
                  *HF-251D-1
                  *WC-1S & Spoolmatic 1
                  PakMaster 100XL
                  Marquette "Star Jet" 21-110
                  http://www.millerwelds.com/images/sm...rolleyes.png?2

                  Comment

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