You should find it in the passenger side kick panel.
on a 91 blazer s10 4wd
No.
any first gen s10 0r blazer or bervada grills will fit
the computer module sets the ratio depending on operating modes,temperate sensor output. more information is in the chilton manual-fuel system.
No.
8-10 psi
No !
4 .5 quarts
If they are both 4x2 and 4.3 engines then yes it will fit, but it will not wire up the same give that the '91 is most likely a 700R4 and the '99 is most likely a 4L60E. One is vacuum controlled the other is computer controlled.
Yes. The original 4.3 is the 5.7 with the front two cylinders removed - it will bolt right up to the transmission, and accept the wiring harness. You will have to swap the Blazer's computer with one from a truck that had the 5.7 though.
I get 12 to 18 mpg with my 91 s10 4.3 4x4 5speed
It doesn't have a reset switch.