Normally, to diagnose an issue like this you start by confirming fuel, spark, air and timing. This is a generalization which covers many things, but will help narrow down the issue.
Of course... be aware that you may have multiple issues compounding the problem. Whatever you do, don't start randomly replacing items. You could easily introduce new issues. New Fiero parts are notorious for being bad before they are even installed.
I'd start with the fuel system since it is easy to check. Two ways to start: 1. spray some starter fluid into the throttle body intake then try to start the car. If the problem is solely fuel related, then it should start. 2. Pop off the fuel line and put the end into a small container. When you turn the key, you should see a stream of fluid. If not, then the problem could be a bad fuel relay (located in the engine bay, on the firewall, behind the driver's seat), or a bad pump (it's also common for the small rubber hose in the tank to fail when the car has sat for an extended period). Before changing the relay or dropping the fuel tank, make sure you look over the wiring first to ensure there aren't any broken wires or loose grounds.
Start with this first and report back if this doesn't locate the issue.
[This message has been edited by Neils88 (edited 11-09-2021).]
