Have you tried tapping on the starter while someone holds the key?  My
starter sticks when it gets hot, and I get the fuel pump buzz but no sound
from the starter.  The solenoid gets stuck and won't move the gear or connect
the motor.  Next time it happens, get out and whack the starter with a wrench
or a board and see if it works.  I keep a small board behind my seat, and I
run around to the right wheelwell and reach in to hit the starter.  There
have been many threads in the archives addressing this if that is the problem.

Bill Marshall
85 GL with stubborn tendencies
Phoenix AZ