Description
The fuel tank in AWD P80s is saddled to accommodate the differential and thus has a lift pump to move fuel from the left side of the tank to the right. Unfortunately, retrofitting an aftermarket pump into the AWD fuel pump assembly is not nearly as straight forward as with the FWD models. The lift pump is a passive design which utilizes the Venturi effect from the returning fuel to move fuel from the left side of the tank into the high pressure sender assembly on the right side of the tank. The high pressure pump is a unique design with dual inlets. One inlet pulls from a pre-filter which sits on the bottom of the tank and the other inlet pulls from the inside of the assembly.
Retrofitting an aftermarket high flow pump into the AWD sender comes with two challenges. The first is physically holding the pump in the assembly, so that the outlet of the pump stays in place and there isn’t a high pressure leak. The other challenge is placing the pump in such a way that the pump inlet isn’t starved of fuel at low fuel levels. A simple retrofit often comes with the unwanted side effect of fuel starvation when hard right cornering when the fuel level is below ~3 gallons.
This product is a DW200 retrofitted into a new AWD fuel pump assembly. The assembly is modified so that the fuel pump inlet pulls from the filter sock at the bottom of the tank. A hole is drilled in the bottom of the assembly to allow for returned fuel to drain back into the main tank. Two aluminum tubes are precision machined to slip inside each other. One tube is press fit on the suction end of the pump and has a step on it. This step acts as a positive stop to keep the pump in place and the outlet firmly pressed into the high pressure sender inlet. Unfortunately, this assembly slightly reduces the minimum fuel level that can be run before starvation. This reduction isn’t much, but the fuel pump inlet will be starved when there is still about half a gallon of fuel left in the tank.
Swapping fuel pumps in the AWD P80 requires dropping of the subframe or cutting an access hole under the rear seat. Alternatively, if the car is on a lift the right side of the tank can be bent downwards enough to give room for swapping the pump without removal of the entire rear end.
