my tachometer is not working properly. at start up the tach goes nuts jumping from 3000-7000 and then it just settles out slammed below 8000. I have an 84 4x4 pickup dlx w/22R. any ideas?

oh first post here by the way. Hello Everyone.....
if your interested this is the build thread on my 05

Thanks for the help!

Edit: and everyone likes pics!!!