Tach suddenly reading high....

[cadrien]

I think. 1995 4.3L, Alpha 1 Gen II. Runs perfectly, noticed yesterday the RPM were reading much higher for a given throttle position or speed than usual. What gets me is the engine sound did not match the higher reading at all. at idle, reading was 1500 yet I can almost guarantee the engine was turning no faster than a normal idle. WOT is typically around 4700-4800, yesterday i was seeing readings close to 6k. Oil pressure never moved and engine temp never strayed from 140. The boat is fresh water only. Anyone have thoughts? Any way to test the pickup or gauge? And to that point, where is the pickup?

Thank you all.

 

[Mischief Managed]

Re: Tach suddenly reading high....

Smack it with your knuckles. Both of the Faria tachs I have owned did the same thing and both were easy to "fix" with a good rap.

 

[wca_tim]

Re: Tach suddenly reading high....

There's a selecter switch on the back, move it back and forth between the settings a few times and then make sure it is on 6 cylinter... There isn't a pickup, the tach counts signals from the ignition system. Were you doing anything down under the dash that you could have accidentally hit the back of the tach? even if not, it's worth a try to move the switch.

 

[bigskiohio]

Re: Tach suddenly reading high....

check the sswitch on back they just have to move a little to screw it up.

 

[cadrien]

Re: Tach suddenly reading high....

Thanks for the replies. I will try the switch on the back of the faria. Is there anything I could have broken in the engine/drive that would cause an increase in RPM? I really do not think this is the case as oil pressure and engine temp did not move, along with the engine not sounding over rev'd. Just want to make sure I look at everything.

 

[WizeOne]

Re: Tach suddenly reading high....

Thanks for the replies. I will try the switch on the back of the faria. Is there anything I could have broken in the engine/drive that would cause an increase in RPM? I really do not think this is the case as oil pressure and engine temp did not move, along with the engine not sounding over rev'd. Just want to make sure I look at everything.

Nothing likely that you could have done. Tachs are just goofy. Apparently all modern tachs are digital. Back in the 70's they were analog. Never had any trouble with those until they quit and now no one services them, even the original manufacturer, if they are still in bidna!

 

[cadrien]

Re: Tach suddenly reading high....

Thank you, Mischief Managed. Had a chance to get the boat back on the water today, immediately noticed the tach was still high. A couple knuckle taps later and it dropped. Funny stuff, thanks again. Love this place, so much knowledge!