Port engine tach will not go over 1000

[Cap3100]

All, can any help me, my port side 5.0 Mercruiser engine tach only goes to 1000 now. the engine seams to be fine. The starboard engine work fine. Does any one have a idea where to start trouble shooting.

2004 3100 MaxumSE

[mmwjr]

Try swapping the gauges to see if it’s the gauge or an issue of the signal getting to the gauge. You can also use a handheld digital tach to verify rpms.

[Gugi47]

Check all the wires are tight.

[jrsick]

try cleaning the connections in the back. The gauge has 3 threaded poles in the back and the wiring harness is push on. Wire brush the poles then apply some dielectric grease.