Question about my tachometer

[Bullrider]

I have noticed my tach is idling around 1200rpm but the 3.0 engine is purring what sounds to me like around 600 to 800. Then I notice the needle jumps to 2100, holds for a few seconds then drops to 1200 only to oscilate back up then down as it happily hums.
I am thinking this is an oxidation issue on some connections.
Anyoneconcur? I plane to tear into this when I get back home.

 

[MH Hawker]

Re: Question about my tachometer

You often need to rotate the pulse selector switch on the back of the tach a few times to clean the internal contacts, that should clear it up, make a note of what position its on before you do.

 

[Bullrider]

Re: Question about my tachometer

Thank you sir!

 

[robert graham]

Re: Question about my tachometer

You often need to rotate the pulse selector switch on the back of the tach a few times to clean the internal contacts, that should clear it up, make a note of what position its on before you do.

Yep, that and check your in-line fuses for just a bit of corrosion on tips of fuses and the holder....clean with 3M pad, a touch of silicone/grease to help keep out moisture from humid marine environment....

 

[gm280]

Re: Question about my tachometer

I have noticed my tach is idling around 1200rpm but the 3.0 engine is purring what sounds to me like around 600 to 800. Then I notice the needle jumps to 2100, holds for a few seconds then drops to 1200 only to oscilate back up then down as it happily hums.
I am thinking this is an oxidation issue on some connections.
Anyoneconcur? I plane to tear into this when I get back home.

If everything was originally working fine and this just started happening, then YES, I concur that some corrosion is taking place. Do what the previous commenters suggested and all should work fine again. Corrosion is a slow worker and can reek havoc when least expected...

Wouldn't be a bad idea to yearly clean as many terminal connections as you can to stop other electrical problems in their tracks too... JMHO!

 

[Bullrider]

Re: Question about my tachometer

This forum is FANTASTIC! Thank you all!