stock tach troubles, help please!

[91frppgt]

ok so i bought a stock 88 mustang gt. and i believe there is a short somewhere, because the tach doesn't work. when i turn the key on it drops below 0 and start it up and stays there. when i turn a signal on or hit the brakes it jumps around counter clockwise to 6500 rpms and stays there. i took the cluster off and made sure all of the connections where good, and they was. i checked the green wire w/yellow stripes on the coil and it was good. is there a ground anywhere? i didn't want to put one of those big ass tele-scopic 5inch monster tachs in the car, but i do need a tach. any help would be greatly appreciated.
thanks
randy

 

[91frppgt]

someone has to know something....

 

[Tonys96Cobra]

Could be that the factory tach is just defective. You could probably find a used one on ebay for real cheap.

 

[ras50gt]

I don't know if i will be any help but i have the same type of problem. My stock tach started doing similar things. It will sometimes go counter-clock-wise, mostly at higher rpms. At idle, for the most part it stays normal but as soon as i throw a rev, it goes counter-clock-wise. Instead of trying to fix it, i just bought a aftermarket 5" tach, which works perfectly. But, it gets annoying to see the stock tach doing that all the time. Someone on stangnet told me that if i have a msd box, then that can cause the stock tach to work incorrectly. I don't curently have a msd box in, but had one and after thinking about it, the stock tach probably stopped working a little after installing the msd box. The guy told me I would need a tach adapter to make it work right. I'm not sure why it still doesnt work now without the msd in, the msd was in for may be a year. So, if you have an msd box or had one, that could be the problem.... Let me know though, if you figure out the issue. I'm tired of my stock tach going counter-clock-wise. OR IF ANYONE KNOWS WHAT ELSE IT COULD BE. Thanks!