In our last episode, we saw our hero, Nehmo, laying in the sodden Kansas mud, various bits and pieces of his fuel system gathered about him..... The saga continues...
As the sky darkened and the gentle breeze gained passion, our hero's dog, Toto, moved closer...... after whizzing on the left rear tire.... suddenly, Nehmos world turned topsy turvy.....
As he regained equilibrium, our hero said "Oh, Wow, Toto.... we ain't in Kansas anymore..... I got the munchies....". And the two combined talents to design a fuel system that Rube Golberg would be jealous of..... after nehmo whizzed on the left rear tire....
Shit happens... some shit happens before we expect and other shit never happens..... In our modern world (spelled "mass production"), two seemingly identical items can be like night and day in regards to traits such as overall quality, general metallurgy, fit and finish and internal clearances.... These factors can have an effect on the life span of any component.
FWIW, my experience tells me that THE MAJOR cause of fuel pump failure is neglecting to change the fuel filter in a timely manner. If this truck has ever been run to the point where a restricted filter has given driveability issues, we can expect a premature fuel pump failure (even though we don't know how many miles or hours are on this nearly 6 year old pump).
If we have ever experienced the inconvenience of a flat tire, we don't set about designing cast iron tires.... If we have ever had a rock chip in a windshield, we don't come up with wire mesh guards....
As for introducing air into the fuel tank.... the motor on the electric pump uses a commutator and brush arrangement. As each commutator bar breaks contact with a brush, a spark occurs..... Your truck doesn't blow up because the fuel vapours in the tank are well above the UEL (upper explosive limit). If we introduce oxygen into this vapour rich environment, we can bring this mixture into the explosive range. And we are still left with the possibility of starving our newly positioned pump.
There is no real concern with allowing our fuel level to drop below 1/4 tank.... but should we allow the level to remain there? As temperature changes, so does the dew point.... condensation can settle on the inner walls of the fuel tank find it's way into the bottom of our fuel tank. Additionally, keeping the tank close to full means we have one less concern should we have the need to suddenly travel any distance... one less concern should we find ourselves in a position where we can't find a fuel source...
While I would imagine that most reading this have experienced a fuel pump failure in their lifetime, I doubt that you'll find many that have experienced multiple fuel pump failures. My last bad pump was on a car with a carburettor...