US Marine Tachometer Troubleshooters?

[Bigprairie1]

Anyone had any luck troubleshooting a U.S marine tach? I recently bought a used (inexpensive) tach off of Craigslist and as things are turning it out...it doesn't seem to be working.
It has the 12 pole/20 pole option on it which would allow it to work with my 90hp however....it ain't working.
I bought it primarily because I like the 'factory' look and was hoping to find an inexpensive matching tach to go with my sparse, but attractive existing gauges. (see the enclosed pic). Well, I nailed the inexpensive part and although the guy said it was working it seems to uninterested in what I'm putting to it.:redface:
I've got the ignition/ground and signal to it...nothing. I even did a direct wire off the engine block for signal...nothing. Set the back pole 'pot' correctly...nothing.
Anyone know if these have an internal fuse or setting or?
This is no great financial loss but if anyone has any insight before switch over to a 'new' tach I'd appreciate any advice.
Thanks
BP

 

[pnwboat]

Re: US Marine Tachometer Troubleshooters?

What year is your motor? The later model outboards that have the Mercury ignition systems use a 12 pole stator I believe. Not 100% sure how many poles but it's not the older 20 pole design of the prestolite ignition systems.

 

[sdxp787]

Re: US Marine Tachometer Troubleshooters?

I am also having a tach problem. I recently removed teh 1987 50HP Force twin cylinder and put on a 1990 90HP Force triple. The tach worked with the twin but not with the triple. Any suggestions? It has the US Marin control system but the boat is a Riviera Cruiser Pontoon. I looked at the back of the tach for some type of switch but there was none. Just the three wires running to it. One for signal, one for ground, and one for the light.

 

[Jiggz]

Re: US Marine Tachometer Troubleshooters?

Not sure if this is the same but take a look at it how he solved his tach problem.

http://forums.iboats.com/showthread.php?t=480376&highlight=tachometer