Beast in Diesel form..

MoparDaddy said
I'm not diesel savy, so allow me to ask an odd question. What does said solutions help you avoid?

It is a light that is activated when there is a lack of fuel pressure. Since the injection pump will still suck fuel and the vehicle will run if the lift pump quits there's not a way to tell if it's going bad until it's too late. This is an inexpensive solution to allow you to monitor the fuel pressure that is being supplied to the injection pump. They are normally preset at around 5-6 psi and if pressure drops below that it lights up.

lou3500 said
1995-1998 1/2 Cummins 12 valve engines used a low pressure fuel system [lift pump on block] just like a gas engine,in mid year 1998 they changed over to a 24 valve engine and started using an in tank pump along with a lift pump creating a high pressure system [the mechanical lift pump was problematic] and was prone to falure if that happens the low fuel pressure [fuel cools the moving parts in the injection pump] destroys the internals of the injection pump [they came up with a modified aftermarket kit] calle a fass system that removes the mechanical pump therefore avoiding falure. This is my reason for sticking with 12 valve engines,plus 12 valves are all mechanically controlled where as the 24 valve engines are computer controlled.

^This is partially correct. The 12 valve trucks used a mechanical fuel pump driven off of a lobe on the camshaft. When the switched to the 24 valve trucks they still mounted on the side of the block but it was converted to an electric pump. They lift pumps have never made enough pressure to be considered "high pressure". Even the Airdog system I have on my '03 only runs at about 18 psi, but has the capability to flow 150 GPH. The biggest problem with the block mounted electric pumps is the heat and vibration would cook them, which would force the VP44 injection pump to suck the fuel through the lift pump from the tank. Since the injection pump is cooled and lubricated from the diesel fuel inside of it this then causes heat and a lack of lubrication which kills the injection pump. The factory "solution" to the early electric lift pump was to move the lift pump into the fuel tank. This let the pump act as a pusher pump instead of a suction pump, and the constant fuel surrounding it helped to keep it cooler. It is a decent solution, but it can still fail. The key to longevity with a VP44 is clean fuel, and plenty of it.