Help fixing bouncing tach

[gazkid]

Have a Volvo 3.0 GS Tach is steady up to about 3800 and then starts bouncing above that. What should I check first. I'm guessing it's not the tach unit itself seeing as its solid uo to 3800. Thanks!

[biggziff]

Have a Volvo 3.0 GS Tach is steady up to about 3800 and then starts bouncing above that. What should I check first. I'm guessing it's not the tach unit itself seeing as its solid uo to 3800. Thanks!

Mine was doing that until I made sure all the plug wires were not touching along their length. I bought some plug wire keepers at Napa for $3 which solved my problem.

[gazkid]

Thanks. I'll try that. Makes sense because the more I thought about it the more I'm convinced the tach was over reading the actual rpm and that the tach itself is ok.

[biggziff]

Also...if your tach is reading too high just give it a few smacks...I read that trick here and it worked great for mine.