I had a pontiac sunfire that caught on fire about 7 years ago. Relay was stuck on for the cooling fan and the wires melted and car went up.
Stuff like that, or "custom" wiring by people who are clueless on proper wiring techniques (i've seen a few scary wiring jobs in the club. feel free to talk to me about custom wiring, you can see what I did on my truck as an example of how it should be).
If you have an older vehicle, it is important to check your fuel lines at least annualy, esp. the flexible ones. I had rubber fuel lines on my el camino completly fail (hoses were less than 5 yrs old). If you are going to run rubber, get the braided stainless hoses, they tend to be higher quality and resist abrasion better (who here isn't smashing and dragging on the rocks?). They can also handle higher pressures. You can get them in teflon, too. Those can handle a lot more pressure and are less sensitive to the environment (engine heat, oil, mud, UV, etc).
