Tach reading high, way high!

[SLewis]

I need some help here. When I turn the key to the on position on my 92 EB Ex the tach goes to 3800 RPM! When you start the engine it reads 3400 RPM. At 80 MPH it reads around 3800 RPM also. Anybody got any ideas on how to correct this? (I just finished rebuilding this truck and have only been driving for a week. The tach was this way when I got it).

 

[MO_GUY]

what did you rebuild? the motor? if so, check your vacuum lines

 

[SLewis]

Sorry for the confusion. I rebuilt the Ex. I bought it with a salvage title and rebuilt it. The only thing I done to the engine was changed the oil/filter and put in a new air filter. The tach was like this when I pulled it home. I looked over the engine and everything seems to be there. I've driven it between 300-400 miles since last Tuesday.

 

[MO_GUY]

are there aftermarket gauges installed? the white faced ones perhaps? maybe the previous owner messed with the tach.....

 

[SLewis]

Nope, it's all stock. Do you or anyone else know where the tach connects in the engine compartment and any test I could do to it?