You mention replacing one injector, so I'll assume it's
the 2.5L 4-cylinder model. First, when looking at that
injector it looks like it's flooding gas all over the
place, but that's how it's supposed to look, like a shower
head going full blast. Have you checked for trouble codes
yet? Do you know how to do that? It's really easy.

The fuel pump puts out way more fuel than the engine
can use at all times, that's why there's a second fuel
line running back to the tank from the throttle body.
This high flow of fuel is needed to cool the fuel pump. The
unused fuel goes back to the tank to be repumped over and
over again. The regulator on the throttle body is what
controls the fuel pressure at the injector, and of course
the ECM controls the fuel injected.

Have you checked for spark? It appears you have fuel, but
have you added a gallon of gas to the fuel tank just to
make sure there's enough? Another check is to look inside
the rocker cover through the oil fill hole and see if the
rockers are moving when the engine is cranking. If not then
the cam gear is stripped, a common problem on older motors
with a history of neglect.

You might also search through the archives at
http://www.fiero.nl in the forums section.

JazzMan