My newly acquired 82 300 CDT has a quirk.

I just searched tachometers under tech help and diesel discussion, but could not find any real help with my PSYCHO TACH!!!! :p
Most of the time... Just lays there... then BLAST OFF!! Its all over the place... 0- 9well not really zero, the un-named line below the five) to 60 then 20 then 30 then 50 then fourty (well you get the point)
Then sometimes very rarely functions just fine... then drops back to the bottom.
should I try cleaning the tach relay pins? Or maybe some die-electric gel?
Or maybe try Prozac in the fuel?

classic signs of bad tach relay if you ask me. It's under the hood driver side, black cylinder about 3 inchs tall. unscrew it and use contact cleaner- if that works, smile. If not price a new one or find one in the yards. You can post a WTB in parts or PM me- I've got one now tested and working in my tool box.

Many thanks to Tangofox 007 sent me a message, now tach is fixed!

Message was...
I just saw your post about the tach. I will bet your problem can be fixed easily. Do a search for "cigarette butt" and "tachometer". Mine did not work for 10 years and the cigarette butt fixed it. Let me know if you can't find it.

found "how I fixed my tach with no tools" By Mr. Goofahrt.

Thanks, guys!