The one on my motor is 27 years old and still working just fine. But don't take that to mean they all will last that long.
The biggest killer of them is old, rotton gas.
Some people will say Ethanol. But Ethanol-containing gas is all we have had for many moons around here. I just fill 'er up at the El-Cheapo gas station and go. Never have had a problem.
They don't generally fail catastrophically leaving you stranded -- usually you get some performance symptoms when they start to weaken. Mine started leaking after around 26 years of service.
