Volvo Penta aq151a tachometer problem

[gordonl]

Thank you for tha add, I am very new to boating, recently purchased a princess 286 with 2 aq151a engines, both run really well and have a good service history, the starboard engines tachometer, shows 5000 rpm at tick over and the port engine shows 1300 rpm, as I increase the revs both meters increase but the starboard engine tachometer goes off the scale, do I need a new meter or could i be something else, appreciate any help - thanks in advance -Gordon

 

[Montemar]

Thank you for tha add, I am very new to boating, recently purchased a princess 286 with 2 aq151a engines, both run really well and have a good service history, the starboard engines tachometer, shows 5000 rpm at tick over and the port engine shows 1300 rpm, as I increase the revs both meters increase but the starboard engine tachometer goes off the scale, do I need a new meter or could i be something else, appreciate any help - thanks in advance -Gordon

Swap the tachos over. The feed comes from the alternator so if the fault moves with the tacho it must be the tacho.

 

[vandy]

looks like a poor connection - remove the tach and clean all connections - also check the alternator side as well.

 

[moresparks]

One quick thing you could try...
On the rear of the Tacho there is a calibration switch. Take a note of the number then carefully rotate the switch a couple of times to see if the contacts are dirty. Then reset back to the original number.

 

[Spi D]

Being new to the Volvo's you may find this link useful:
http://boatinfo.no/lib/volvo/manuals/131_171.html#/0

I agree about the faulty reading on one tach. Sounds like signal corruption by bad connection somewhere.

Your idle should be 900 rpm (ensures that transmission works as designed to and allows for low speed manouvering). Before doing much you should check tachomenter accuracy (eg. by a handheld wireless laser tachomenter, universally reads anything spinning, approx £10 on ebay)