Tachometer problem...

[Guvner..]

Rewiring an older bass boat with a 115 HP Evinrude outboard motor. Motor runs fine but went to change the tachometer as it went underwater and it only seems to have two lead terminals on it. Several positive and presumably one sending wire go to the one terminal and the other terminal has a negative wire. I tried to imitate this as much as possible on a new tach I got but got nowhere. No movement at all. It is a Medallion tachometer. Any thoughts as to what tach would work best to replace it?<br /><br />Thanks... Gary

 

[OBJ]

Re: Tachometer problem...

Gary...<br /><br />Tachs usually have a three wire system. "S" for signal or the gray wire on OMC/Bomby engines, "I" for ignition or 12V source and "G" for ground.<br /><br />Check out iboats store for a tach. Believe they are Tele-Flex gauges. Be sure to get one with in your engines operating range.

 

[Guvner..]

Re: Tachometer problem...

Jim... Thanks... That was fast. I have some suspicions about the new tachs and my older Evinrude. I have heard I need to add some kind of resistor or something to use them. Do you or anyone else know where this goes? I have an 88 Johnson on my Pontoon with a new Teleflex on it and it works fine if I touch the terminals on it but nothing if I leave them alone. I'm sure it has something to do with this resistor thing. I just can't find any documentation on this thing.<br /><br />Thanks... Gary

 

[OBJ]

Re: Tachometer problem...

Honestly Gary that's a new one for me. Course I generally install OMC/Bomby products. I would think that if a resistor is needed, it would be in the instructions that come with the instrument. I've seen a few older tachs with resistors on them but can't remember on what. Are you sure the posts on your tach are not lose?

 

[Guvner..]

Re: Tachometer problem...

Jim... You've got me. I'm an HVAC guy so I'm pretty picky about my wiring and I just noticed it because I had the dash board bolts out while running and pulled it up and started checking the connections to see what was up with it. As I touched any of the terminals it started to work. As soon as I pulled my hand away it died. It might be an open ground. That would make sense. I didn't pursue it at the time. Just kind of bewildered me at the time and I remembered the resistor stuff I had heard... <br /><br />Thanks... Gary

 

[Guvner..]

Re: Tachometer problem...

Just found the part I saw on Teleflex's site... Here's a paste..<br /><br />** 88-115 HP “Special” models may require addition of an OMC Voltage Regulator <br />to the engine, or a 2,000-ohm (or larger) resistor to the rear of the tach.<br /><br />A resistor to the rear of the tach doesn't sound like a detailed wiring diagram... <br /><br />Thanks... Gary

 

[OBJ]

Re: Tachometer problem...

Maybe ya' just otta go see a Johnny/Rude dealer and get a Bomby tach. No fuss no muss....hook it up and go.

 

[DJ]

Re: Tachometer problem...

Perhaps your tach is "case" grounded. Meant to go in a metal dash?

 

[Guvner..]

Re: Tachometer problem...

What is a Johnny/Rude dealer. I just tried an internet search for that and a Bomby tachometer and came up with zilch.<br /><br />Thanks... Gary

 

[Lark40]

Re: Tachometer problem...

JohnnyRude=Johnson/Evinrude.<br /><br />Bomby=Bombardier, current manufacturer of Johnson/Evinrude products.