Does a backfire on my 1994 GMC Sierra 1500 means that I need a new fuel pump.? and how do I get the fuel pump out? where would be located?

....hold on a minute there, turbo---you've got a fuel filter and fuel pressure regulator, does the motor stop turning evey once in a while? yes it is in the tank, with any luck an access hatch above this pump....messy business.~

Backfire sounds like a premature spark...aka timing---think yours has a distributor, in which case I'd look at the vacuum advance mechanism jumpin' the gun or missing the boat...out of adjustment or the vacuum line is leaking or missing off that one...back off the spark (as long as you've a distributor) to where there isn't a backfire~

your vacuum lines are sucking air, recommend replace the butyl rubber ones with the more expensive silicone that will never decay and leak~

Is your motor a vortec? If so and it backfired thru the intake inspect intake. Vortec has a plastic intake and will crack or other wise have some sort of damage after a backfire.