tach problems

[jim phillips]

I am trying to get my tach to work. If I run a wire from the batt. to the batt. side of the unit and a ground from the batt. to the unit then touch the sig. terminal to the gray wire at the moter it will work.I ran a new wire from the moter to the dash and hot and ground from the fuse block and the damm thing wont work. What am I missing here it must be simple but I cant get it.

 

[SlowlySinking]

Re: tach problems

lucky jim, 1. use a voltmeter and verify 12 volts at the hot and ground tach wires in the dash with the ignition ON, if that's good then there's only one thing left, the signal wire from the engine. 2. Try this, ground the engine end of the tach signal wire, then check for 12 volts at the tach end using the signal wire from the engine as the ground and the 12 volt hot wire from part 1. If you don't get 12 volts the tach signal wire is some how bad, if you get 12 volts then I'm stumped too. Good luck. Ken

 

[jim phillips]

Re: tach problems

I ran a new wire from the moter and even tried a hot and ground lead from the batt. to the tach nothing works. I used 18ga. wire form the moter to the tach could that be the problem?

 

[SlowlySinking]

Re: tach problems

Hi lucky jim. Is this a new tach installation, if not what size was the original tach signal wire, possibly it was a shielded wire. I just don't see how the wire size would matter, it only carries a signal and there's no voltage drop problem, but I've learned to never say never, any thing is possible. If it works when connected directly to the engine but not at the dash and if you have power to it I can only assume the wire is the problem. I can't think of any thing else. Before you replace the wire again try this, with the engine running and your meter set to AC volts check the signal wire to ground voltage at both ends and see what it shows. If you don't have an AC voltmeter let me know, Ken

 

[jim phillips]

Re: tach problems

I dont have one that I can put my hands on

 

[Ralph 123]

Re: tach problems

From the ABYC Standards:<br /><br />

Conductors shall be at least 16 AWG (except 18 AWG may be used as internal wiring in panelboards). Conductors shall have a minimum rating of 600 volts (E8.14.1.1). All conductors and flexible cords shall meet the requirements of the applicable standards of Underwriters Laboratories, Inc. (E8.14.1.6). Flexible cords shall have a minimum of 300 volts (E8.14.1.2).<br />

 

[jim phillips]

Re: tach problems

OK Ralph in plan english does that mean that the wire is to small?

 

[Ralph 123]

Re: tach problems

seems so. Also, note that there is a difference between SAE wire gauge size and AWG. AWG is bigger for the same gauge number.<br /><br />Try some marine 16 awg or 14 awg

 

[SlowlySinking]

Re: tach problems

lucky jim, contact me directly at wn2sqc@juno.com <br />thanks, Ken

 

[jim phillips]

Re: tach problems

I will try it in the morning<br /><br />Any other thoughts would be welcome

 

[Ralph 123]

Re: tach problems

Jim,<br /><br />Also take a look at this for reference:<br /><br /> http://www.tflx.com/gastachsel.html

 

[jim phillips]

Re: tach problems

Ralph I have it wired just like the pic except the hot wire comes from the hot side of the fuse block

 

[SpinnerBait_Nut]

Re: tach problems

lucky jim, there are 2 things that could cause this problem.<br /><br />1. You have been standing downwind with bubbakat. <br /><br />2. It's them dang aliens again. <br /><br />Sorry, I could not resist.

 

[jim phillips]

Re: tach problems

 

[jim phillips]

Re: tach problems

Will a auto type tach work or does it have to be a marine tach ?

 

[gaugeguy]

Re: tach problems

Generally speaking an automotive tach may or may not work, depending on what type of engine the tach was made for. Most tachs that are made for marine applications will work on the automotive side also because of the rotary switch on the back (you can change for 6cyl, 8cyl etc), but most tachs made for the automotive side are made for a specific engine and don't make the crossover as easy. As far as the wire size goes, although 18 is not recommended, it isn't gonna give you the symptoms you are seeing. A tach just doesn't draw that much current (200 ma. max). You really need to look at your voltages with a multimeter to see what you aren't getting. The good thing it is only one of three things...voltage, ground or signal.

 

[jim phillips]

Re: tach problems

I borrowed a meter and checked some things<br />12 volt at the tach<br />new wire from motor to dash is good<br />Now when I tried to get a reading from the gray wire connection at the motor I set the meter on 25 volt DC ground the black lead to the motor and touch the gray wire terminal with the red lead I get nothing ...I'm I doing this right?

 

[gaugeguy]

Re: tach problems

So far so good. With your engine running at about 2000 rpm or so, you should read about 5 volts AC for an outboard and about 5 volts DC for an inboard or I/O. One other thing you can check...do a continuity check on your ground. Set the multimeter on ohms and put one lead on the back of the tach and the other on the engine and verify a near zero ohm reading.

 

[jim phillips]

Re: tach problems

All right <br />I have a working tach Now what do I set the dial on the back to. It has numbers 1 through 6<br />It was on 6 and when I throtted up It maxed out I then set it on 3 because that is the number of cylinders i have and it seemed to work but is slow to respound I had to get the rpms way up to make it move

 

[gaugeguy]

Re: tach problems

What type of engine do you have?