both tachometer not working

Ransnan

I have a 2003 342 with horizon 350 mag MPI, couple months ago the starboard tachometer started reading about 2000 RPM higher than what it should be at cruising speed, and 200 rpm higher at idol, Now the port tachometer is reading about 1400 lower than what it's supposed to do be at cruising speed, any ideas or suggestions on what it could be ?

Stodge

Bad ground, corrosion at the terminals on the tach, or the coil where it's read from.  Could also be the round black thing that feeds the sync meter as it has tach connections to it as well.  Might want to pull the dash open and check for corrosion/ bad connections/etc.

Ransnan

 the sync gauge does work, that would be a good place to start, didn't think of that !!  

Stodge

So then I'd look at the connections on the tach.  I've heard (from some on here) that some tachs have a switch on the back to specify 4, 6 or 8 cylinder.  That switch may have gotten vibrated out of place or have some gunk. If you find those, might want to slide them back and forth a few times and park them firmly into the right spot.

Black_Diamond

Called tap-tap gauges for a reason. Those Faria tachs are junk. You can send them back to get fixed/repaired to Faria. 

rmrstlmo

I'm having a similar issue with my 2000 340 FV.  The tachs are not consistent but the sync gage seems like it might be working.  Does the sync gage work independent of the tachs?  In other words, can the tachs be messed up and the sync is truly giving me good info?

Black_Diamond

Yes. 

Handymans342

do you know where the sync gets its signal?

frenchship

Here it is.
Paul

Handymans342

Thanks Paul but where is the lighting pigtail located on the motor?

frenchship

The lighting pig tail is right behind the dash it come from the light switch for the dash lights at night .

frenchship

,I had my Faria tach repair twice by Faria still did not work properly(repair are not free even that they carry a life time warranty)
So I went with Floscan that has a built in sync gauge, and I replace the Faria sync gauge with a dual hour meter, the floscan tach when in sync both engines are running within 50 RPM. That was check with the Rinda scan tool.

Stodge

That's a nice drawing Frenchship, wish mine looked like that.  Mine has the posts with spade connectors and wires instead of the nice plugs like that.

Handymans342

frenchship said:

The lighting pig tail is right behind the dash it come from the light switch for the dash lights at night .

Huh???? where do the sync gauge signals hook on the engines?

Stodge

The ignition wires that measure tach go to the "base"  which figures out the difference and sends that to the sync gauge.

Handymans342

I don't have ignition wires lol

Stodge

Oh so do you listen to a playing card on the flywheel and count the clicks to get RPM?

frenchship

Handy,
your first question was regarding the lighting pigtail........?

schematic for tachs connections on 5.0 MPI.

Handymans342

I will have to do some more research

HishamKinani

Can someone please explain to me what is the function of the sync gage and how its related to the tachometers .. Tks

TonyWalker

Easy enough re the sync gage.  When it is centered, both engines are at exactly the same RPM's or "in sync."  Once you get familiar with the boat you will be able the "hear" that they are sync.  If not there will be a noticeable vibration or rumble coming from the props not running at the same speed.

HishamKinani

Thank U very much Mr.TonyWalker .. allow me to grab the chance and ask another three questions : 
- if only one Engine is running , will the sync gage be functioning , and in this case what would be the position of its needle ? 
- if the sync gage is not functioning (working) at all , what would be the reason and would it affect the proper functioning of the tachometers ? 
- To my understanding , i can assume then that if both the sync gage and the tachometers are functioning properly , then either if in idling stat or full speed stat the gage should always be in the middle !! am I right ? Thank U in advance for your cooperation . 
Hisham Kinani

TonyWalker

A centered gage means that both engines are turning at the same RPM whether slow or fast.  If the sync gage itself fails, I imagine the tachs will not be affected by the failure and will operate normally.

 

Since any two Faria tachs will read a bit different from each other at the same true RPM, I find it best to bring both engines up to speed with the tachs, set the RPMs using the tach you trust most.    They should be reasonably close in true RPMs at this point as indicated by the tachs and by the sound.  Then use the sync gage to make fine adjustments to one engine or the other

 

A fuel flow meter makes these adjustments even easier but that is another subject.  I recommend you install one at some point and if you see value in this..

 

With just one engine running, the sync gage will point hard to the dead engine side.  With both engines running, but one turning slightly slower than the other, the gage will point toward the slow engine.

 

You can touch up the speed on the slow one or you can reduce speed on the fast one.  But it is quite sensitive and you will need to get the feel of it, which is quite easy to do.  You will learn to grasp the tops of both throttles with your right hand and will get the hang of doing a rocking action between them to make adjustments as needed.

 

I hope those explanations are clear.  Ask further if there are still issues.

 

Tony

Salt Shaker 342

HishamKinani

Thank U very much Mr.Walker, you've been a gr8 help and I reckon that I'll always be needing your valuable experience and advice re my new 342 Fiesta Vee/37' footer/2005 (Lady Nadine), as for the past 12 years I owned a Bayliner 3250 Conquest (Flybridge) model 1982 powered by two volvo penta AQAD40B/DP, obviously its a totally different tech. Compared to my new 342 which didn't touch the water in Egypt yet (The Engines has only 160 hrs on it NY license) .
I am much interested in your suggestion re the fuel flow meter , but I need to know what is it and how it works , where should it be mounted , will I be needing two meters or only one and finaly from where can I buy it.
Again thank you very much for your cooperation and apologize for any inconvenience . Hisham kinani from Cairo , Egypt .

TonyWalker

Just one gage for both of your engines.  I will be able to provide some more info in the next couple of days.  In the meantime someone else with a fuel flow meter may want to jump in while I am out of touch.

TonyWalker

And how nice to have a member who boats on the Mediterranean and the Nile.

HishamKinani

Also fishing on the Red Sea as I have another 22' footer bowrider Bayliner, I customed it specially for fishing .

Handymans342

Watch out for those ISIS pirates!

TonyWalker

Here is the flowscan website.  These things are really really useful.
http://www.floscan.com/html/blue/recreationalmarine.php

This is the one I have.
http://www.floscan.com/html/blue/seriesdetail.php?sid=14

TonyWalker

There is another advantage in having the Flowscan system.  You know how much gas you have used within one gallon or maybe 3 or 4 liters.  This allows you to take trips that are much longer between fuel stops than you would otherwise feel comfortable doing with just the gas gages.

Ransnan

Well after much troubleshooting,  I come to the conclusion that BOTH tachs just quit working a month apart, at least it's at the end of the year, sending them back for warranty repair, hopefully they'll work better next year !