Tach wire on 95 GT40

[FULL-THROTTLE]

Anyone know what wire is the tachometer lead from the engine on a 1995 Ford GT40 EFI??

My tack is acting up, reading 2k at idle, theres no way it's at 2k its more like 800rpm's

Thanks

[vvfdfirefighter]

I haven't worked much with the GT40 but normally it's the purple wire coming off of the coil. Should be on the negative terminal

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[villain]

Purple will be ignition hot. Grey will be your tach lead. It is the wire on the negative side of coil.

[FULL-THROTTLE]

Thanks for the responses, My coil is mounted on the left side of the air inlet of the fuel injection system, it has an electrical connector so it is not marked as neg or pos.

Fran

[foxriverat]

My tach was acting up last year. There is a calibration screw on back of tach. Mark where the screw is set at. Then turn the screw back and forth as many times as you need to. Corrosion gets in there and this will loosen it up. Worked for my tach.