My tach has been bouncing, as other's, '88 240/M47, and sometimes stopping altogether until hot??? So I started with the entire ground system under the hood. The two grounds on the fuel rail were badly greened, were snipped, and a new fasteners soldered on with anti-corrosion applied. That actually cleared up bad throttle response in the morning when cold and accelerating through 2nd and third gears.

The tach, however, took longer. First pulled the intrument cluster, cleaned up prongs where it plugs in, applied anti-corrsion, re-assembled, nothing! Went to the coil, burnished spade connector on terninal #1, anti-corrosion, nothing! STill bounced, sometimes, dead other times? This morning, I thought, why not. And I snipped off the wire containing two leads, separated the white with red stripe (Tach) from the 14 guage white, soldered new separate spade connectors and gave the two wires their separate positions at #1 spade connector at the coil. Jumped in, hit the starter, and presto!, steady tach needle.

I'm getting really fascinated with this little car the more I fix, and the better it runs. It's truely a wonderful little car. Thanx to all for posting about all these things and giving me a better hands on method of being a DIYer.

Update, today I looked down and the tach was dead on the bottom. I watched as I drove home, nothing. No bounce either. Later I went for bread and milk, and bingo, there it was opperating as normal right from start up and back home.

I think there is something wrong internally, electrically. Maybe a transistor or some other internal component. Not to worry, it doesn't bounce when it is working. It's like the radio, out of nowhere the right or left speaker goes dead, and then comes back on!

Nice! Your catching the bug though, watch out! I have thought that many times especially after fixing numerous things for cheap and without much hassle. "What a wonderful little car." Lot's of others don't get it, but I don't care, at least I can pay my bills and I'm at nobody's mercy! Keep it up and you'll save yourself lots of dough and have fun doing it.
Charles

Yes ChazzyD, and while the world flys by to the next traffic light stop, we gleefully coast through after it turns green, myself enjoying repeated tanks of fuel at 25.1 mpg, around town. My wife won't ride in the Volvo since I took out the AC. Go figure, more fun for me. A real life hobby filled with rewards and gremlins as one mystery after another holds us transfixed in what to others seems a daydream!

Now get your wife one! Dan