Tach acts funny

[skyguy59]

Alas, Russ is probably chasing ghosts again. 1972 100 HP Johnson,Teleflex Tach. Everything works perfect except, when at idle I put it in forward gear the tach needle jumps up 150-200 RPM. The engine speed does not change.I have verified the RPM with a hand held tach. Back to neutral or reverse and the RPMs go back down and agree with the handheld. It will do it in or out of water and is pretty consistant. It does it with or without the throttle cable connected so I'm sure its electrical and not a rigging problem. No other changes in any other instrumentation. Any ideas??<br /><br />Russ In Texas

 

[Barnacle_Bill]

Re: Tach acts funny

Check all your connections, especially grounds. Be sure the are clean and tight.

 

[ob]

Re: Tach acts funny

Also insure that the tach is set exactly to position 6 .Not sure on Teleflex but my OMC tach position adjuster doesn't detent into position ,but has smoothe travel.Mine was taking periodic dives in readings above 5000 rpms, and a closer inspection of it revealed that it was set between 5 and 6 position.Adjusted it and it solved my problem.With a little luck ,it may be yours.

 

[skyguy59]

Re: Tach acts funny

I've already redone all of the grounds and then double checked them when the other pack failed. I'll double check the setting before I run it the next time. Thanks guys<br /><br />Russ In Texas