95 Z. Ran fine yesterday, today cranks but won't start as if getting no fuel. No audible fuel pump priming sound when ignition is turned on. Don't have a fuel pressure gauge but would be willing to bet there is none at all.

Question is this: is my fuel pump definitely toast, or is there a cutoff engineered into the engine management system related to 'service engine soon' light or anything else?

Also, how difficult/pain-in-the-*** is a fuel pump swap? Any firsthand stories?

 

It's not hard to check the fuel pump circuit. You'll need a multimeter and wiring diagrams, of course. The fuel pump relay is underneath the "dead" pedal. You can check for power to and from the relay. If the relay gets power it means the pcm is not turning it on (or those wires are bad). If the fuel pump is getting power it has to be wiring, a fuse, or the pump itself. Make sure and do your diagnosis first so you don't end up wasting money. Although fuel pumps going out on LT1s isn't unusual, usually it goes out slowly. If it dies suddenly I would suspect an electrical problem. I'm pretty sure if the PCM doesn't turn the fuel pump on there's a security light that will remain illuminated.

If you do diagnose it make sure to study the diagrams carefully, some relays are ground side switched, I can't remember if the fuel pump relay is one or not.