www.autozone.com , after putting in your car's info, and under the Free
Repair Guides, then Fuel System, has a pretty good drawing of the main
relay's location. Figure, 2, lower right-hand part.

It's near one's left knee but under the left dash cover as seated in the
driver's seat.

It's best to have the new relay in your hand and try to match up shapes, if
possible.

IIRC a flashlight was helpful when I changed it on my 1991 Civic LX years
ago.

Reports here are that one does not have to remove the entire relay; the
"guts" can be removed by itsself, and this will save you a lot of trouble.

Beg no more. See here:
http://www.tegger.com/hondafaq/mainrelay.html
Your Civic's will be in the same location as the '91 Integra in question.

It's actually called the "PGM-FI Main Relay" (AKA "EFI Main Relay". The
fuel pump is only one of the several things it controls.

for the 88-91 civic, it's in a slightly different location to that shown
in the faq's.  it's mounted against the door frame, directly above the
hood release catch.  it's a total sob to get at.  lie on your back in
the foot well, with a flash light, & you can see the mounting bolt.  the
faq's will get you close.  after that, look for the orange underside you
can see in this pic

http://www.tegger.com/hondafaq/mainrelaylocation/7-main_relay_closeup.jpg