2003 70hp issue

[99yam40]

part of the link and sync is checking timing also to make sure it does stay in spec at idle ad WOT
a timing light will show you what the motor is doing with timing and it should show that you have good spark on all cylinders if you move the induction pick up to each plug wire

as was said different motors can have different number of magnets under the flywheel so pole or pulse settings can be according to the motor you have, but most old school 2 stroke outboards should use the same type of tach, just need to adjust the settings.
newer 4 strokes can get signals from the ECU and give lots more info to the tach

[panasonic]

Installed a new pump and housing, no more buzzer.. However, it still doesn't seem to be at full RPM. Is there A special tach for a 3 cylinder so I can be more accurate?

Pick your choice off Amazon...small digital tach. I have two and they work well.

https://www.amazon.ca/Inductive-Hour...lbWF0aWM&psc=1

[99yam40]

I have read some of the inductive tachs can have trouble with the other plug wires inducing stray signals into the pick up wire if routed too close to them.

[panasonic]

I have read some of the inductive tachs can have trouble with the other plug wires inducing stray signals into the pick up wire if routed too close to them.

Yes that is true...just tywrap the wire away from the other plug wires and they work good.