How do I replace my alternator on my 1984 Fiero

Hi Diego.
try this link.
Pontiac Fiero Workshop Owners Manual Free Download
or this one.
pontiac fiero workshop manual from the year 1984 Google Search

did you check the ground on the body also

remove the small wire from the solenoid and try it again if it cranks then you have a defective starter

not the right gauge...to many volts

disconnect the battery lead from the starter plus any other wires undo the starter flange bolts that hold it onto the motor then it should pull straight out.....hope this helps .....cheers

Look at the 2.8 Chevy S-10 info. Same engine

If you got the correct replacement alternator, the connector wires should just plug directly in to the new one. Make sure you have the right one, any thick red wire is the output to the battery, the rest i'm not sure, just compare to the old alternator you took out, maybe match up by comparing wire colors

Check the brake light switch. It's located under the dash by the brake pedal. Disconnect the electrical connector from the switch. Jump the connector with a paper clip. Be careful not to let the paper clip touch a metal surface. If the brake lights come on then the problem is a faulty brake light switch.

9 times out of 10 its a timing issue when ive changed headgaskets;)

possibly O2 sensor, sensor tells car fuel/air mixture. check oil, make sure not leaking