Autozone's online Repair Guide has a surprisingly extensive collection of wiring diagrams.
Otherwise one of the popular hard-copy manuals like Chiltons & Haynes, but not all them are strong in wiring. Can probably sneak-a-peek at one on the shelf at the auto parts store.
There are other for-fee/pay sources, but I've not used them.
The library - an old-fashioned idea I know, but... Might find the more comprehensive service manuals there.
The window washer pump should be located in the bottom of the washer reservoir for the 1998 Sable. The reservoir may have to be removed to replace it.
Open the rear liftgate on a Mercury Sable wagon and you will see the rear window washer fluid reservoir fill plug near the bottom of the passenger side tail light
On a 1990 Mercury Sable : The ELECTRIC fuel pump is INSIDE the fuel tank ( it is installed through an access hole in the top of the fuel tank )
I believe the "Related Question" below specifically addresses replacing the door glass on a Taurus / Sable.
Mercury Sable was created in 1986.
mercury sable
For a 2005 Mercury Sable : The electric fuel pump is INSIDE the fuel tank It is installed through an access hole on the top of the tank
Press the button on the rear hatch that has the key hole in it. This will release the window catch and it should open when you try and lift the window.
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Inside the fuel tank with the electric fuel pump