Foton 704 tach stops working after warm up

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    • March 9, 2018 at 3:30 pm #47703
      GNXGuy
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        Ok

        Now that I can start my tractor again I’m on the troubleshooting one more problem

        First the tachometer works for about 15 minutes give or take as does the hour meter. After the fifteen minutes or so the tach needle drops to zero and the hour meter stops advancing, but I can still see the hour meter digits. I swapped out the tach with a brand new one that I had and it performs the same way works for 15 or so minutes till tractor warms ups

        I pulled the dash to make sure I had all good connections.

        Does anybody know where the tach pick up is on these tractors

        Thanks again for the help

        Joe

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      • March 9, 2018 at 6:53 pm #47707
        DavidPrivett
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          I think yours is like most there is a pick up that is triggered by magnets on the flywheel look there . I think the pick up it screwed in till it touches then backed out 3/4 of a turn. There is a plug in connection there also that might be giving you trouble.

        • March 10, 2018 at 2:01 pm #47712
          GNXGuy
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            It’s actually 5 minutes that it stops working. I’ll give that a look next time I’m out at my farm in a few weeks or so.

            Thanks

            Joe

          • March 10, 2018 at 2:11 pm #47713
            Bob Rooks
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              David got it right except the magnets are located in the reluctor. It actually “counts” the flywheel teeth and the digital pulses are converted to an analog signal for the tach needle. Over time the reluctor will gather oil/dirt and just require cleaning and resetting.

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            • March 10, 2018 at 3:01 pm #47715
              GNXGuy
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                Thank you Bob

                Where exactly would I be looking.

                The only access to he flywheel that I can think of would be where the starter mounts and where one would do the clutch adjustment. Is there a removable inspection panel? I just peaked under there and did not see anything that jumped out at me.

                So I took a peak behind the dash had did notice an electrical connection on top of the bell housing. Would this be the sensor? See photo

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              • March 10, 2018 at 3:21 pm #47717
                Bob Rooks
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                  Yep, that’s it. Disconnect the pigtail electrical connection and remove it. When you reinstall it do as David said, screw it in until it just touches the flywheel and then back it out 3/4 turn and lock it. Be sure it doesn’t turn when you lock it.

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                • December 8, 2018 at 6:51 pm #48384
                  GNXGuy
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                    OK only 9 months later, I finally got this thing back to my shop to work on it.

                    After washing the engine, the tach worked for a while. Concluded the water completed a connection in a broken wire.

                    Anyway, it was a BEEEEEECH to remove this thing there is just no room (I have a enclosed cab model). Got it out and found a broken wire at the sensor. Ordered new sensor and installed and all seems to work during my test starts.

                    Thanks for the assistance.

                    Joe

                  • December 9, 2018 at 1:50 pm #48387
                    Bob Rooks
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                      Certainly glad you’re up and running again.

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