Negetive Voltage Kaw FH680V DS13

Discussion in 'Mechanic and Repair' started by RickyDL77, Sep 21, 2010.

  1. RickyDL77

    RickyDL77 LawnSite Senior Member
    Messages: 431

    Let me start by stating this is the first time ever posting anything here, but have found answers many times here in the past from other posts..this site is very much appreciated and thanks.
    Ok so I have a 5 year old Wright Stander 52" with Kawasaki FH680V DS-13 with arround 3100hrs, was rebuilt about 8 months ago replacing rings, seals, Valves, everything seemed to be within spec, and the engine was doing fine before the overhaul with the exception of a few leaks. Once I put everything back together and tested for leaks I sent back out on a crew...came back next day with a dead battery. I checked battery was good, Charged and started and checked the charging system and emediatly noticed the voltage was dropping on the gauge when rpms were raised.

    1. replaced voltage regulator did not solve problem
    2. checked Charging coil resistance and tested within specs
    3. tested AC voltage from coil tested within specs but was a negetive voltage?.. didnt even know AC voltage could be i bought a new voltage didnt change
    4. thought might be a bad wire somewhere on the mower so i took engine off machine and "jumped" started so that no battery was involved, same problem

    By this time i had no other thoughts of what it could be so i put it in storage until i found any info on it..

    5. called wright manufacturing and told Chris what was happening after i had 2 more machines do the same thing, 1 after a rebuild and other just out the 3 machines down, He called me back the next day after talking to his mechanics and said they have never ran into this problem before (negetive Voltage) only thing they could come up with was "bad Ground" and "perhaps a worn upper crankshaft bushing".
    6. August... decided to buy all parts for charging system and replace everything.. fixed the probelm, then i isulated it to the coil being bad and put it back in service
    7 Now a month later it is back in the shop with the same problem:confused:

    First Question would be how does it put out a negetive AC voltage? What are the chances of a Flywheel causing the coils to go maybe the magnets got depolerized or something like what happenes with generators when sitting for long periods

    Any thoughts, theories, jokes would be welcome thanks
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,334

    To have 3 with the same problem, It just about has to be something you or 1 of your employees has done to these mowers.
    I dont know if its possible to install a stater upside down, or what the effect would be.
    Is the battery hooked up correctly ? reversed polarity ?
    Are the wires to the regulater hooked up properly ?
    Does the regulater have a good ground ? A poor ground will give you problems.
    Does 1 of your employees have a Wright Stander voodoo doll in his truck ?
    Who knows....If all else fails , check your shop with a geiger counter , there might be an old tesla experiment buried around there..
  3. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,334

    Make sure you have 12 volts to the power wire going to the regulator. The regulator will not turn on until it senses voltage. It might be using the voltage in your meter if you dont have power and a ground to the regulator. This can give you some wierd voltage readings, and possibly damage your meter.
  4. scottr 2006

    scottr 2006 LawnSite Member
    from alabama
    Messages: 70

    Many years ago I was troubleshooting something that had been dunked in salt water. There was a voltage across dissimilar metals bolted together. Maybe a employ has spilled a drink on something or peed on something causing this same problem.
  5. RickyDL77

    RickyDL77 LawnSite Senior Member
    Messages: 431

    it doesnt seem to be anything with the wiring, i have taken the engine off the machine and placed on a homemade engine stand and started by "jumping" the starter with a jumpbox, completely eliminating any 12v system... then tested AC voltage from the stator and its between -10 through -14 with rpm low to high.. im only the "shop mechanic" so in my case im the low man on the who's who here, trying to get any info from the crew's is virtually impossible.. i do know that they have been known to jump other machines from another machine alot.

    Geiger counter? what might this be? to be honest i have never been to school for small engines other than courses to be certified in specific equipment (redmax, Wright Stander, ect.) but been doing this pretty much none stop since 06 and this is the only thing that has gotten me stumped.. BTW i have stated that someone might be putting a hex or sabataching these machines but they just laugh. the Company i work for has 25 crews roughly with 3 to 4 Wrights on each and they do dog the mess out of them. These 3 machines with the same charging problem all have one thing in common, they sat without being ran for more than 1 month when the initial problem presented itself.. 2 of the 3 didnt have charging problems before the overhauls

    Think im going to replace the stator agin for this one that failed a second time, in addition i will replace the entire wire harness, engine wires, ignition switch, and PTO switch and send it out to be destroyed once again lol
  6. RickyDL77

    RickyDL77 LawnSite Senior Member
    Messages: 431

    lol i'm going to copy this post and send to superiors, the seasonal guys here on maint crews have been known to do some akward things like the possibility of "peeing" on the machine...brake fluid for hydrolic oil, 10w30 for 2 stroke mix...not the brightest bunch of workers, but they do the job well.
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,334

    Try this...

    Install a jumper wire from the neg terminal on the battery to the screw that attaches the regulator to the engine.
    Install another jumper wire from the pos terminal to the hot wire going to the regulator.
    Run engine and check battery voltages.
    If it doesnt improve . the problem is either the stator or the regulator
  8. RickyDL77

    RickyDL77 LawnSite Senior Member
    Messages: 431

    I have tried that already. I know its the Stator at this point and it was the stator that i replaced originally, but what can cause the stator to keep failing?

    Unregulated Stator Output
    • Disconnect the connector [A].
    • Connect AC voltmeter to the stator pins .
    • Start the engine. Run the engine at the 3 000 rpm speed.
    • Voltage reading should be minimum 26 VAC/3 000 rpm.
    If the AC voltage reading is less than the specification, replace the
    Unregulated Stator Output (MIN)
    26 VAC/3 000 rpm

    Pins(B) being the output wires for the stator, conected a multimeter to the 2 pins and started engine. Meter set to AC voltage iit read -26.7 to -30.2
    I then did the same test on another machine that was charging corectly and got arround the same voltage readings but without being a negative voltage.

    originaly thought maybe im trying to look to far into the negative voltage and replaced the stator, voltage regulator, and flywheel and it worked fine for a month or so..but now it's doing the same thing. i still have the original Stator which "failed" and tested it's resistance and checked for any ground leaks and compared to that of a brand new one...both were identical.

    I have talked to another machanic that does side work for us and he told me to short out the 3 terminals on the voltage regulator and that sometimes revives a dead charge? wasnt to sure about that but after nothing else worked i tried, nothing but a very strong arc, like that of a welder. and a blown fuse...replaced the fuse and still a negative AC voltage from Stator.

    Machine has no history of blowing any fuses before or after this charging problem started, but it has had a fuse holder replaced about a year ago because of not making a good connection
  9. scottr 2006

    scottr 2006 LawnSite Member
    from alabama
    Messages: 70

    I have three questions for you. First , what are you using for a reference when you measure the voltage ? Second , were impak wrenches used with the regulator installed ? Third , what method is used to jump start these units or are these units used to jump start other equipment ? You can use a dc voltmeter with the negative lead on the battery negative terminal to test other metal parts on the unit for galvanic action(battery voltage caused by corrosion) just probe the suspected area with the positive test lead.
  10. RickyDL77

    RickyDL77 LawnSite Senior Member
    Messages: 431

    Kawasaki Service manual for FH451V - FH721V
    Impact wrenches are used all the time but only for replacing blades and wheels by the crews. I used one for changing other parts like spindles ect, but not on the engine. I used a small 7.2v snap-on drill when disassembling the engines, but a torque wrench to set the bolts.
    When they jump the machines they use a pair of jumper cables from machine to machine. I figured it couldnt hurt them so long as they dont hook them up backwards seeing as they dont have any sensitive components like today's automobiles.

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