Tach quit working...where to start?

[VA Chris]

The Tach on my 1998 Mercury 115 4 cylinder ELPTO quit working recently. It has been a little wonky for over a year. It would max out sometimes and a little tapping would put it back down. I just want to know where to start looking for the cause of the error. If it is just the gauge, fine, I'll replace it, but I dont want to buy a new one if it is something else. Another point I should mention is my engine does not have a rev limiter on it. A few years back it went bad per the mechanic at the nearest Tracker dealer in Hagerstown Md. He told me I would be better off to not replace it and keep the RPM's in the specified range. so far so good for 4-5 years but without a tach I am going on "Feel". Any help is appreciated and if a certain brand of Tach is better than another I'd like a little advice on that as well.



Thanks in advance



Va Chris

 

[Bob Bourget2]

First I would check battery voltage...with motor off {should read 12.5V+/-}, and then at about 1500 rpm...since your tach is inop, just above idle. You should see 13.2+/-. The reason...if your stator / volt regulator is inop or not functioning properly, the tach reading could be off, inop, or inaccurate.

Check all wiring / connections, especially the purple "hot" lead.

 

[VA Chris]

Thanks Bob, you're the man. Have a nice Christmas

 

[Jeffry Skidmore]

+1 what Bob says about the wires. I recently replaced my tach after experiencing similar symtoms only to find out that the "hot" wire was almost in two. Spliced that back and evrything was hunky-dorey! BTW anyone need a tach; I've now got and extra.

 

[VA Chris]

Still having Tach issues. I have checked the voltages and all looks good. I have 4.2 AC on the signal wire (grey), 12.7 volts on the purple (off) and 13.4 purple (motor at idle). I thought it was a bad tach so I bought a new one, hooked it up, and still no tach. What now? I am at a real loss as to what to do at this point except take it to the shop but it would be two weeks before they could even look at it.I really dont want to have my boat out of commission for that long this time of year.

 

[Scott Hammer TOXIC]

This is just a guess on my part but isn't there a setting on the back of the tach? What are the chances you got a bad one out of the box? Sounds like it has to be at the motor if I were to guess.



TOXIC

 

[VA Chris]

I guess it could be bad out of the box but what are the odds. I did check to make sure the setting was correct on both tachs (6p)for my 1998 115hp elpto. I dunno, maybe Bob will chime in. God love him, he puts up with a lot of questions from us

 

[Bob Bourget2]

Try running a separate {external} gray {signal....doesn't have to be gray for the test...} wire from the regulator to the tach....

 

[VA Chris]

Thanks Bob, I'll give it a shot over the weekend and let you know.

 

[VA Chris]

Ran the jumper. Still got nothing. Beats the heck out me

 

[Bob Bourget2]

When I get to work tomorrow, we'll get you the test for the regulator...next in line to test...

 

[VA Chris]

Ok Bob, Just let me know how to do it. Ready when you are. Thanks again

 

[Bob Bourget2]

You have e-mail.......

 

[VA Chris]

Hey Bob, I pulled the cowling and to test the rectifier per the diagram and instructions you sent (thanks)but I am either blind, a nitwit or both because I cant find anything that looks like the diagram you sent me via email. I posted a link to my photobucket account that has some pictures i took. Maybe if you have chance you can take a look and tell me what/where i am supposed to be looking for.



Also there is an extra purple wire and a brown one too (connected to nothing) down low in one of the pics. I believe it has always been unhooked and I assume it is just disconnected because my boat did not need it to run anywhere, but I am not sure. Thanks Chris



http://s925.photobucket.com/albums/ad98/seetrice/



To recap- I have 12.4 volts motor off and 14.4 motor on at the tach and 4.2 volts ac at grey signal wire and a jumper from the engine to the tach did not help.

 

[VA Chris]

apparently I do not know how to post a link but you can copy and paste in your browser. CT

 

[VA Chris]

Geez,I'm an idiot
http:// http://s925.photobucket.com/albums/ad98/seetrice/

 

[VA Chris]

ok, the link wont work for some reason but the cut and paste does. go figure

 

[Bob Bourget2]

Can't access it...maybe e-mail me the pic?

 

[VA Chris]

I know the link will not work from NTOW site for some reason. I emailed the link to you, it should work (did for me) otherwise just copy and paste the link into your browser. Thanks Bob appreciate it.l