Erratic tach

[bwana50]

The tachometer on my '96 SN is doing weird stuff. At idle, it'll show anywhere from 700 to 3000 rpm. Usually the swings are fairly small, around 500 rpm, although the actual RPM has obviously not changed. I haven't noticed the problem as much at speed (busy "watching the road", so to speak), but I have seen it move around there also. It'll show what seems to be correct RPM for awhile, then wander off for a few seconds and come back. It never drops to 0, so I don't think it's bad ground or other connection, but it could be, I guess. Any ideas on where to start diagnosing this?

[Mikeski]

RE: Erratic tach

the 4/6/8 selector switch is dirty, it's a common issue. Pop the dash move the switch back and forth a few times and put it back together. I had to do it once a year with my 1995.

[nch20skier]

RE: Erratic tach

What do you mean by the 4/6/8 selector switch?
I have also read that this could be due to a bad voltage regulator which is often the case if the boat has been jump started.

[Rick]

RE: Erratic tach

The Tach has a selector on the back for 4 6 or 8 cylinders. If your alternator is chargng the battery its probably not the regulator.

[JUST-IN-TIME]

RE: Erratic tach

try rotating the switch and cleaning connections
your not the first one this happened to