My wife's 2003 Pontiac Sunfire's fuelpump went out @ 47,000 miles and cost $820.00 to replace. My mechanic, who is trustworthy, said it's a common problem in GM cars. And it's a GM Only part. Of course, the warranty expired at 36K. But if it's a manufacturer defect GM should share the bill right?

Nope sorry, the fuel pump is not only a part that is used every time the car is started but also continues working for the entire time the car is running. It is a mechanical part, they will fail at sometime or another. While I agree with you it sucks that it failed at only 47,000 miles but that is well out of reach for any help from any manufacturer, not just GM. If it was within a couple months of the end of 36 months or 36k miles they would likely help you out. But a year late and 11k miles out of warranty they won't help out, sorry.

It isn't common enough, and it didn't go out early enough to claim manufacturer's defect unfortunately. You can write GM and ask for consideration, but I wouldn't hold my breath.