1994 Mariner 60 Hp and Faria Tach Failing after 3/4 throttle

[kytooner]

Installed a new Faria 7000 rpm tach suppose to be suitable for motor.

Tach is steady and constant until I hit 3/4 throttle and then it just goes to zero. Back of throttle and it's back to steady. Mfg Faria suggested the setting may not be exactly on setting. I checked the pole position and it appears to be in the correct position.

 

[Texasmark]

What is the indicated RPM at 3/4 throttle....>7k? Your actual RPM is around 3800-4k. A 2:1 difference in the setting could make it peg..if wrong in the wrong direction. I am currently running a new
Farina I bought a year ago and it has no problem with my engine...but it doesn't run 7k.

 

[Faztbullet]

Check the signal input as rectifier could be dropping out. Should have a steady AC voltage that climbs with RPM

 

[kytooner]

What is the indicated RPM at 3/4 throttle....>7k? Your actual RPM is around 3800-4k. A 2:1 difference in the setting could make it peg..if wrong in the wrong direction. I am currently running a new
Farina I bought a year ago and it has no problem with my engine...but it doesn't run 7k.

Tach is 7K possible. At 3/4 it's throttle (maybe a bit more) it's hitting around 3500 K It's just when I push the throttle that extra inch to wide open is when the tach drops.

 

[kytooner]

Tach is 7K possible. At 3/4 it's throttle (maybe a bit more) it's hitting around 3500 K It's just when I push the throttle that extra inch to wide open is when the tach drops.

So tried again today it's solid until 3500 to 3700 rpm all day long. 3800-4000 rpm which is getting close to full throttle it goes to zero. If I keep running at full throttle it will eventually come back up but it's not solid and bounces alot.

 

[Faztbullet]

See post 3

 

[kytooner]

See post 3

Thx I"m a little slow both in testing, understanding, and posting (winter came along). Looks like your assumption is right. I've come to realize that my voltage at a constant 18 volts isn't right.