Tach reads wrong

[demsvmejm]

Hopefully this is the proper forum for my question. My Farria tachometer reads approx 1000-1200 RPM at cruising speed. I used one of my professional-grade meters to monitor actual RPMa nd found 3500-3800 on my Mercruiser 3.0L I-4. I've checked ground and Voltage. The only feed I haven't checke dyet was the actual tach signal. The connections on both ends appear clean, bright, and secure. Any ideas? Are these tachs serviceable? I contacted the Thomas G. Farria company and the idiot who responded was totally clueless. Thank you to all.

 

[rabidfish]

Re: Tach reads wrong

Some(most) tachs are adjustable to work with several engines. <br /><br />On the back of your tach, there should be a dial with a pointer pointing to numbers arranged arond the dial.<br /><br />You should be able to adjust this dial to make the engine rpms more in line with what your shop tach reads.<br /><br />Without knowing what engine you're running, it's hard to sat which "setting" your tach should be on. Just adjust it to match your shop tach.

 

[waterone1@aol.com]

Re: Tach reads wrong

The switch on the back that Rabidfish mentioned is also notorious for getting dirty contacts and causing a wrong reading. Just flipping the switch around a few times usually corrects this problem.

 

[demsvmejm]

Re: Tach reads wrong

LAst fall I checked for the switch, and it was set right(?). Wehn sprin gfinally gets here I'll check for the problem waterone1 mentioned. And Rabidfish, I'm running a Mercruiser 3.0L I-4. You know the GM 4 cyl.