Just got my 2003 3rd gen. Since I got it I've only put in an Airaid drop in filter and gauges in the cubby hole. With the three gauges in, I installed a fuel low pressure light that works off of approziamely 4-5 psi. After install the light was on all the time except at idle. I then changed the fuel filter which was pretty dirty. Now the light will come on at about 1100 RPM.

The lift pump makes a good noise and allowed me to bleed the system after the light install at the banjo fitting, and also after filter change. So do the pumps ever loose their effectiveness gradually or do they just go out. It is the stock pump on the side of the fuel filter. Truck has 130,000. Wouldn't a stock pump in good shape be able to keep the light out?

 

Those canister mounted LP's were notorious for going out.....that is, unless yours has been retrofitted to the tank....let's hope not! I guess over time they could become weak but at any rate it will fail!!! If funds allow, look into an AirDog or a FASS....they both work great but I have had VERY GOOD CUSTOMER SERVICE WITH AIRDOG .