1997 v4 looper tachometer

[limacina]

Admittedly I haven't even started to dig into this problem; but I'm one to collect info before jumping in.
I noticed in my last few end of season runs that the tach on my starboard engine was going flaky. I got real readings some times and other times when both engines were running at the same RPM around 3k, the STB would show 1k to 1500 or be bouncing from zero to 1k.

So, am I looking at a failed tach, a loose wire, or an engine sensor failure? As I write this I realize I should have swapped the port and stb tach while the boat was still in the water.

Any suggestions or past experiences would be appreciated. I'm putting together my to do list for the winter.

 

[Barnacle_Bill]

Re: 1997 v4 looper tachometer

Tachs get their signal from the stator. The connection is made at the rectifier since the same leads feed it. So to answer your question, it could be the tach, wiring, rectifier or stator. The most common reason for tach problems is your rectifier.

 

[Chris1956]

Re: 1997 v4 looper tachometer

That motor has a water cooled voltage regulator. Replacement cost is high. I recommend you check the connections (purple for +12V, grey for signal and black for ground), before replacing the VR

 

[limacina]

Re: 1997 v4 looper tachometer

I was a little worried it'd be a rectifier problem. before I got the boat, they had rigged up dual batteriesfor dual motors with a switch for each motor to access either battery. Its a good system if you know how to use it; but you can never run the switches on "both" and the previous owner ran all the time this way. I read that both engines charging a battery will usually burn out the weaker of the two rectifiers. Again, I haven't had to much of an issue yet until the tach acted up and I have a habit of making sure I alternate which motor is charging which battery so I know both engines will start on either battery in an emergency so if at rectifier failed, i wouldn't notice right away.

Any of this make sense? am I misinformed about the dual motors and charging?

 

[Chris1956]

Re: 1997 v4 looper tachometer

I do nopt think that the weaker VR would burn out, when running in the "both" position,however it is mute at this point. You need to figure out if the motor charges, and if it doesn't charge, repair it.

 

[HighTrim]

Re: 1997 v4 looper tachometer

I would definately start by testing your rectifier as per Joe Reeves instructions in the FAQ. If it is faulty, replace it immediately or disconnect it until you can replace it.

The next step will be to determine why it blew. Ensure battery connections are clean and tight to start.

I am kinda confused (easily done ), about your battery and switch setup. Are you running 4 batteries, 2 per outboard, on a perko switch? Are the 2 batteries for each motor independant of the other 2?

If the R/R is fine, you can easily test the tach by swappin it with the known good one.

 

[gyoung]

Re: 1997 v4 looper tachometer

If you are going to switch batteries while running your engines you must use switches that make contact with the new battery before breaking contact with the old battery or your rectifiers could be damaged. Could this be your problem?

GY