problem with tach

[SVT3183]

in the fall before i put my car away for the winter my tach started acting up. when i was at idle sometimes it would read at 0 rpms, the needle was literally resting on the stop pin. when i gave it some throttle it would jump up and read where it was supposed to when i was driving. i haven't really noticed it as a problem since i've been driving it again this spring, but now the problem seems to be worse. the rpms are now reading low, even when i'm driving. they seem to be about 1000 rpms too low. it's not a constant thing though, sometimes it does show the correct rpms. has anyone had this problem before? can the tach itself go bad or would it seem like something else? i have no clue

 

[The Green GT]

Pull the cluster and check the tan wire with an orange stripe.
Thats the tach wire.

 

[1TallMF]

I would have to say its probably something wrong with the tach itself, since that wire only carries a ground pulse from the coil, I can't see it not sending the proper signal intermittently, unless of course its chaffing on something causing it to temporarily ground itself out. You can pull the cluster and check that wire, but I'd put my money on the tach being at fault. Ford gauge clusters aren't anything to brag about.

 

[SVT3183]

can just the tach be changed or would i need a whole new cluster?

 

[SVT3183]

i called msd today and they said i could need a tach adapter because of the 6a. i also run a blaster coil. did anyone else have a tach problem after installing a 6a?