What is the fuel pressure in a 2003 Chevy Avalanche?

The fuel pressure in a 2003 Chevy Avalanche depends on the engine. There's no single answer. You need to specify the engine size (e.g., 4.8L, 5.3L, 6.0L).

Once you provide the engine size, you can then look up the correct fuel pressure specification in a repair manual for that specific vehicle. You can also find this information online through sites specializing in automotive repair information (though always verify with a reputable source).