I just installed a sun pro II tach on my 2000 Explorer 400 and something has to be wrong, it says it is ideling at 2500 RPM and it buries the tach at 1/4 throttle. I hooked it up using directions from a scrambler 400, I'm lookin for some advice, please help!!

 

im not sure bout that tach but some have a switch for how many cylinders it sounds like that is what could be wrong

 

when I put it on the 4 cyl. setting it reads a 4000+ idle RPM, when on the 8 cyl. setting it reads 1500 RPM, I dont quite understand what I did wrong. It revs way past the 8000 Rpm max on the tach way to fast as well, this has to be wrong as well, I hooked up the tach to the yellow/red wire by the oil tank, this is what I read on earlier post's was right.