Tachometer jumping around.

[akintosyali]

New faria tach. The needle is jumping around. ideas?

[MikeP]

Check the tach connection to the coil and ground; this is often the problem. BUT I have seen faulty tachs do the same thing. One would like to think that a new tach couldn't be bad but...

I'm assuming that the tach jumping is not accompanied by engine misfiring or surging. If that's the case, then it's probably not the tach at all.

[Karl]

New tach, old wires! Check the wiring before you do anything else. Unless you've replaced the wiring already, test it out by running a good wire from the tach to the sender by the shortest route and see how they function. I bet it's the wiring.

[akintosyali]

i plugged the ground from the good tach to the tach that jumped around an ther was no change. I will clean up the wirs on the old tach tomorrow.

[Nonchalant1]

Maybe it's the connection from the spinning tach cable to the sensor. Mine has a 4 inch square end cable that got rounded off over time and started slipping, making the tach jump around. I replaced the cable ($13 from Detroit Diesel) and it has been fine ever since.

Doug Shuman

[Genesis]

Diesel or gas?

If diesel, and especially if you have a sync, this is a problem with worn cables and/or the take-off from the hydrico pump.

The fix is to replace the worn components.

[david_lavigne2540]

On my Gas 426 Engine on the front was the cable that was a spinning type, not a sender unit. But a picture is worth a thousand words.

[King Size]

akin: until you get those motors running smooth, and the valves adjusted properly, you cant expect the electronic tach to give you
good #s. And the name is KING SIZE not kingfish. King Size by the way
was my dads Boeing B-29...need I tell you what the nose art was, she was
Blond and King Size. Jeff.

[Avenger]

King Size by the way was my dads Boeing B-29

Pictures????

I mean of the plane, by the way. Nose art I'll leave to your judgement.

[yachtsmanbill]

C'MON!!! I collect nose art ! That stuff was AOK before it became "genderically incorrect". Give it a name like "rhinestone cowboy" and youll be safe tho... ws