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3556 Views 11 Replies 4 Participants Last post by  jimmyj900
OK fellas'
Back to tachometer problems again.
My tach only starts to work when I get to 50mph. At that time, it goes right up to 4500rpm and increases to 5000rpm at 60mph. When I get below 45mph, it drops to 0. Has anyone run into this problem before, or have a suggestion????? (Wife's getting upset with me coming into the garage at 50)

Secondly. Spark plug gap????????????
Book said 8MM to 9MM. Not having gauges in MM, I converted that to .020/ .022. Does that seem about right???

As usual, any suggestions is appreciated...

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The easy one first...

1.0 mm = 0.039 inch, so just multiply milimeters by 0.04 for a good approximation.

8 to 9 mm then is .032" to .036"

The tacho...

Well, we've been over a bunch of really odd possibilities on this sort of problem before.

The first thing I'd suggest is swapping the #1 and #3 ignition coils.

If the problem goes away, you've got a bad ignition coil or bad connections.

If the problem stays, remove the tach and clean the contacts and wire ends that screw into the back.

Give the above a try and let us know how it works.

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I'm hoping that a shop here in Atlanta may be able to check the tach out or maybe rebuild if it is in fact the tach, not the igniter.
Don't hold out a lot of hope for a repair since it's an electronic tach and considered a 'throw-away.'

If the shop can't fix it, e-mail me.

It might be possible to add an input filter to the tach and stabilize the behavior, but I'd need a bad tach to experiment on.

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