FUEL-04, Fuel Pump Delivery Rate - Checking


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Tools

Procedure

    NOTE

    Be sure to have rags ready to catch excess fuel when disconnecting fuel lines / caps. The fuel in the fuel rail may be under high pressure and may spray if the fuel rail cap or lines are removed too quickly.

  1. Slowly disconnect the return line from the fuel pressure regulator (FPR) going back to the fuel tank.
  2. Using a hose clamp attach a hose to the discharge of the FPR that is long enough to reach the measuring container.
  3. On early cars (pre-1985.5), remove the fuel pump relay (located under the dash on the driver's side (left-hand drive)).
  4. On late model cars, remove the DME relay located on the fuse / relay panel under the hood.

    NOTE

    Be prepared to start the timing device as the fuel pump will start as soon as the jumper is installed.

  5. On the panel where the relay was removed (early or late model), jumper terminals 30 and 87b. The fuel pump should start. Start the stopwatch as soon as you hear the pump start running. If you aren't sure which terminals are the correct ones, refer to the terminal number labels on the bottom of the relay.
  6. Allow the pump to run for 30 seconds and then remove the jumper to stop the pump.
  7. Determine the amount of fuel collecting in the measuring container and compare to the table below.
  8. Values significantly below those listed indicate a problem with the fuel pump, fuel filter, or fuel dampener.

    Fuel Pump Delivery Specifications
    Most Fuel Pumps 850 ml / 30 sec. (28.7 fluid ounces)
    Pumps With Green Paint Code
    Bosch No. 0 580 464 028)
    750 ml / 30 sec. (25.4 fluid ounces)

Clark's Garage 1998