i have a 95 chevy blazer that we put a rebuild in and the motor has horrible gas milealage. It gets prolly 10-12 mpg. the motor is the stock 4.3 and i cant figure why its wulfin down gas. any ideas?

 

I would suspect either a really tightly built motor which may loosen up as it breaks in or it is possible that you have an internal fuel leak...

 

where could the fuel be leakin from inside?

 

Internal fuel lines or fuel pressure regulator. The CPI motors are known for this type of problem. And It is possible that during the reassembly after the rebuild that the internal lines were tweaked. If they were removed and not replaced, that right there is enough to cause a leak.

 

did you hook up the 02 sensor?

 

yeah