[ItsDC]

I completely overhauled the engine in my truck (1988 Ranger 4X4 w/2.9). It runs great, smooth no problems at all, except---.
Here's the catch the tachometer runs backwards (not exactly backwards but more of a reverse, with the engine off the tach rests at full deflection of the gauge "7000 RPM" when started the tach reads about "6000 RPM" as the engine is revved the needle move to the lower numbers "5000 - 4500 RPM" and will not go lower than 4500 RPM). Now, all who have worked on this type of equipment before know that the wiring harness is such that it CANNOT be wired backwards. Now here is another interesting bit of info. I thought that the needle might have flipped due to an electrical spike while reconnecting everything. So, I took the cover off the tach to manually flip the needle back to the correct position. Get this, the truck would not start after that. I put the needle back to the "WRONG" position and the truck started. I repeated the procedure with same results. What I'm thinking now is that I missed or have a bad ground. I think it's trying to find a ground through the tach. What do y'all think? Thanks.