Lazy Tach Reading

[wncrjb]

I think I know the answer to this but I need verification....

On my 1988 3.0 mercruiser, my tach seems to read slower than the RPM of the motor.
I hooked up my multi meter to it today to double check and I was right, When the dash tach was reading 1500 RPM, the multi meter was reading about 1950 RPM.
I cleaned all the connections on the coil and on the tach guage itself and it made no difference.

On idle, they both read close to one another, but as the RPM increase, the difference in guage reading become farther apart from each other.

I think my tach is heading south but I would like to see what you all think first.

I also noticed the multi meter will fluctuate around too at times.... if the RPM is at 1800, the meter will jump between 1600 and 2000 RPM. Is this normal for a multi meter or could I have ignition problems too?

I gave this thing a complete ignition tune up very recently and it runs great.

Thanks for everything,

wncrjb

 

[Barnacle_Bill]

Re: Lazy Tach Reading

I've been using multi meters many years but never seen one that measured RPMs. What kind to you have?

 

[wncrjb]

Re: Lazy Tach Reading

I've been using multi meters many years but never seen one that measured RPMs. What kind to you have?

You would have to ask the name of it when it's in the shop right now.....LOL
I believe the name on it is ACTON but not sure.

I'll get it for you tomorrow and let you know.

I mainly got it for my boat because it also has a dwell meter in it also.
I remember getting off e-bay last year for like $30.00 new.
It comes with a book that tells you all kinds of stuff it will test.

wncrjb

 

[Barnacle_Bill]

Re: Lazy Tach Reading

OK, I think I know what you are talking about now. I have an old one thats called an engine analyzer. It measures dwell and rpm and some other things but its made for automotive work.