The Bosch fuel pumps used in Porsches are generally extremely reliable and not prone to failure. If you have a fuel pump that needs to be replaced, there is likely something else that has caused the fuel pump to fail. So, before you simply replace the fuel, you may want to see if there is another problem that caused the fuel pump to fail. A clogged fuel filter can cause failure of the fuel pump. A failing fuel pressure regulator can also result in pump failure. It's a good idea when installing a new pump to perform a fuel pressure check and pump delivery rate check. This will check the condition of the entire fuel system and may prevent pre-mature failure of the new pump by identifying potential system problems.
Tools
Metric wrench / socket set
Catch Rags
Hose clamp pliers or locking pliers
Jack stands and floor jack OR ramps
Removal
Depressurize the fuel system as follows:
Remove the fuel pump fuse. On 1985.5 and newer cars the fuel pump should be supplied via the DME relay through Fuse 34 (15A) on the Central Electric Panel under the hood. On pre-1985.5 cars, the fuel pump is supplied via Fuse 2 on the Auxiliary Fuse Panel (under dash driver's side - LHD).
Attempt to start the engine. It may or may not start. If it does start, allow it to run until it stops due to lack of fuel.
Disconnect the battery negative lead.
Raise the rear of the vehicle by placing it on jack stands or ramps.
If the vehicle is equipped with a cover for the fuel pump (at the bottom of the fuel tank) remove the fuel pump cover. The cover will have a strap holding it to the bottom of the fuel tank and a single bolt (13 mm head) near the wheel well.
Disconnect the electrical leads from the fuel pump. Depending on the model of the vehicle, you may have to disconnect the lead from the pump or there may be a two prong plug connector near the pump that may simply be unplugged.
Using hose clamp pliers or locking pliers, clamp off the line from the fuel tank to the suction of the fuel pump. If regular locking pliers are used, it's a good idea to wrap the fuel line to keep the teeth on the locking pliers from damaging the fuel line.
Fuel Pump Electrical Plug
Loosen the hose clamp on the fuel pump suction line and disconnect the line from the pump. Have some catch rags and a pan ready to catch any residual fuel which will drain from the line.
Using the appropriate size wrenches, disconnect the discharge line from the fuel pump.
Loosen the hose clamp holding the fuel pump and slide the pump out of the holder.
Installation
Prior to installation of the new fuel pump, compare the fittings to make sure the new pump has all the correct fittings. If all the correct fittings have not been supplied with the new pump, transfer fitting from the old pump to the new as necessary.
Slide the new fuel pump into the fuel pump holder. Tighten the clamp that holds the fuel pump in place. Do not over tighten the clamp as it can damage the fuel pump motor.
Attach the suction line and discharge line to the new fuel pump.
Remove the hose clamp from the pump suction line.
Connect the electrical leads to the fuel pump.
Connect the battery negative lead.
Install the fuel pump fuse (see Removal section for fuse location).
Start the vehicle to check for proper operation of the fuel pump and to check for fuel system leaks.
If equipped with a fuel pump cover, install the cover.
