Tach reading goofy??

[SRD art]

Hey all, not sure if this is electrical or interior forum section, but I need help regardless. The tach in "Grandpa", my new to me 84 Cutlass is reading what seems to be 800-1000 rpms too high. The car is all original, very much virgin and untouched, so I'm at a loss for what would cause that. Is this a common problem? Thanks for insight.

 

[GuysMonteSS]

There is someone else having tach issues as well.
Here is a link to that post and you can read my reply's as they will quite likely apply to you too;

Tachometer stutter

84 El Camino. Out for a cruise around the block the other day. While driving, noticed the tachometer dropped to zero, came back up to ~1500, dropped down to zero then back up to normal again. On today's drive, didn't see any issues. Presuming it's the electrical connection where the gauge...

gbodyforum.com

Guy

 

[ck80]

I doubt it will help you, except gm is gm...

Back when I owned fieros, there was 'something' about them that cause them to read at about 500 to 1000 rpm even when the engine was off. I remember being told on forums how common it was as a problem, but, that was 20 years ago so I can't remember why they did it.

Might be a similar issue though, just a suggestion of somewhere to dig if you have no other leads at a moment in time.

 

[L92 OLDS]

This issue with the cutlass rally pack is well documented. There is a switch on the side of the rally pack that lets you choose between a six or 8 cylinder. If the contacts get corroded it will cause erratic tachometer readings. You can clean the contacts and hope for the best or solder in a jumper wire to fix it.

 

[SRD art]

Thanks for the reply fellas. My son also has the rally pack in his Cutlass wagon and it used to jump around, so we figured it was the filter. The car was in an accident and we haven't got around to rebuilding it yet so we never did check the filter. The 4 door doesn't seem to be erratic at all, it's just reading too fast. Anubis- Thanks for that insight!! I will definitely look into that. Maybe that's the issue with both cars?