Tach Problems

[Chieflet]

I have a 1993 V4 90 hp Johnson outboard. Recently the tach seems to be playing games. It will show the proper rpm's then drop to ) then back. Someone told me it might be my voltage regulator. Is this true? Any other comments?

 

[iwombat]

Re: Tach Problems

It _could_ be your rectifier, but highly unlikely. The rectifier is just a series of diodes. They're either fried or they're good. Theoretically, one could be going out intermittently, but I'd wager large sums of money on it not being the cause. Look for a bad ground on your tach, bad power lead, or bad sending wire first.

 

[Chieflet]

Re: Tach Problems

I did those things and have not found any problems with the wiring or ground.

 

[iwombat]

Re: Tach Problems

Here's the rectifier tests from the FAQ, just to rule that out. One for each type of rectifier.

http://forums.iboats.com/showthread.php?t=190638

http://forums.iboats.com/showthread.php?t=190636

 

[reeldutch]

Re: Tach Problems

check for battery voltage around 3000/4000 rpm it should be 14v or a little more.

if not your rectifier voltage regulator is on its way out.
you want to replace this puppy they do get hot and might start a small fire.