Merc Tach.

[POINTER94]

88' Mercury I/O w/350 cid, 260hp and an alpha. Started the engine this year and it ran great which it has since I got it. But this years little surprize is the tach isn't working. Seloc is useless, and I can't find a 350 specific drawing.

Any ideas why this happened, what it might be, and how to fix? It was working great when I put her to bed last fall. Engine runs outstanding but I have heard your can take out your ignition if the tach is not working right. ????

 

[Flukinicehole]

Re: Merc Tach.

Check the ground on the coil first, in most cases this is the problem. Take the ground off and clean real good see if this helps.

 

[Don S]

Re: Merc Tach.

A defective tach will not "Take Out" and ignition system. I will short the ignition to ground and cause you to loose spark, but it will not damage the ignition system.
Tachs sometimes go bad after setting unused for a while.