Tip & How-To about Mercedes-Benz E-Class

Fuel systems on cars

2) Fuel: From tank to engine

The modern fuel tank is fitted with a sealed filler cap. Set within the fuel tank is the fuel level sender which sends a signal to the fuel gauge indicator on the dashboard. Fuel is drawn by a pre-pump (lifter pump),also within the tank, through a filter 'sock' or strainer to prevent bulky debris rom entering the fuel line; the pre-pump maybe located outside but near to thefuel tank. Also connecting to the tank is the fuel return pipe and often on top of the tank can also be found a pressure sensor. Associated with the tank there is often an expansion vessel to accommodate thermal expansion of the fuel. Finally attached to the top of the tank, or top of the expansion vessel, there is a fuel vapour recovery pipe that is part of the evaporative loss emission control system employed to prevent fuel vapour release to the environment (see later in this series).
Fuel is pumped from the tank by the pre-pump through the fuel line towards the engine: on some systems a further 'main' fuel pump may lie between the fuel tank and engine. The fuel, now under considerable pressure, passes through an in-line fuel filter that removes any fine particulates before they reach the engine. A clogged fuel filter puts a strain on the fuel pump so routinely changing the fuel filter can help prolong the pump's service life. On reaching the engine compartment the fuel line connects to the fuel rail mounted on the engine. The injectors feed directly off this pressurized fuel rail. Mounted onto the end of the fuel rail after the injectors is the fuel pressure relief (FPR) valve which governs the fuel pressure in the line all the way back to the fuel pump(s).
The critical component within the FPR is a spring loaded diaphragm whose role is to maintain a constant force on the relief valve. Fuel, pressurized by the action of the fuel pump, is forced against the valve and excess pressure allows fuel to bleed past to the return fuel line back to the fuel tank. Attached to the top of the fuel pressure regulator is a vacuum line connected to the inlet manifold. The vacuum partially offsets the action of the diaphragm spring. When the engine is at idle, the throttle plate is closed and the manifold vacuum is at its greatest (lowest pressure), the strong vacuum sucks back on the diaphragm against the spring pressure allowing a reduction in the fuel pressure needed to open the relief valve. This reduction in fuel pressure helps minimize fuel consumption per each injection cycle when at idle. Conversely, when the engine is running at high speed, the throttle is wide open creating little or no vacuum in the plenum. This reduces the pull back on the FPR diaphragm and consequently the fuel pressure in the fuel rail is at its highest.
In 'common rail' designs the injectors are controlled by the ECU. The ECU controls the injection cycle time (pulse width) and, in very modern systems, the actual injection pattern. When the car is at idle the injection times are short and when under load the injection times are longer. Similarly when the engine is cold (as indicated by the engine coolant sensor to the ECU) the injection times are longer to ensure a richer starting mixture. The combination of injection time, along with the fuel pressure in the fuel rail, dictates the engine speed and fuel consumption.
In recent years evaporative loss emission control systems (EVAP) have been introduced to prevent the escape of fuel vapour from cars. The fuel vapour that evaporates from the surface of the fuel in the tank is conveyed by the vapour relief pipe to a charcoal filled canister. The fuel vapour is stored in the charcoal for later use by the engine. Access to the stored vapour held in the canister is controlled by electrically operated valves. When the engine is cold the charcoal canister purge valve is kept closed. At normal operating temperature (signalled from the coolant temperature sensor to the ECU) the purge valve opens allowing the stored vapour to contribute to the air in the inlet manifold. The charcoal canister also has a vent valve operated either electrically or passively, in response to internal pressure drop, which when open introduces fresh air to help flush residual vapour out of the charcoal canister.
NEXT 3) Spark: from battery to spark plug

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2 Answers

How to replace fuel pump on 2005 chevy monte carlo


The pump is in the gas tank, so the tank has to come out.

Apr 28, 2016 | Cars & Trucks

1 Answer

location of and how to remove and replace - 2002 DeVille Sending Unit/Fuel Pump Module (4.6L engine)


These units are in the tank and must be dropped in order to replace.


WARNING Do not handle the fuel sender assembly by the fuel pipes. The amount of leverage generated by handling the fuel pipes could damage the joints.

  1. Relieve the fuel system fuel pressure, as outlined in the Fuel System Section.
  2. Drain the fuel tank to at most 3/4 of a tank full.
  3. Raise the vehicle.
  4. Remove the fuel tank.
    NOTE The modular fuel sender support assembly will spring-up when the locking ring is moved.
  5. Remove the fuel sender assembly using tool J39765 Fuel Sender Locknut Wrench or an equivalent.
  6. Note the position of the fuel sender strainer for installation.
  7. Support the reservoir with one hand and grasp the fuel sender strainer with the other hand.
  8. Pull the external fuel sender strainer off of the fuel sender.
  9. Inspect the fuel sender strainer. If the fuel sender strainer is contaminated, the fuel tank should be cleaned.
  10. Discard the fuel sender strainer after inspection.
  11. Disassemble the electrical connectors from the fuel level sensor assembly of the fuel pump and cover assembly.
  12. Disassemble the fuel level sensor assembly.

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    Fig. Fuel level sending unit on fuel sender (fuel pump) module.


To install:
  1. Assemble the fuel level sensor assembly.
  2. Assemble the electrical connectors to the fuel pump and cover assembly.
  3. Position the new fuel sender strainer on the modular fuel sender and push on the outer edge of the fuel sender strainer until the fuel sender strainer is fully seated on to the sender assembly.
  4. Install the fuel sender assembly into the fuel tank using tool J39765 Fuel Sender Locknut Wrench or an equivalent.
  5. Reinstall the fuel tank.
  6. Lower the vehicle.
  7. Add fuel to the fuel tank.
  8. Connect the negative battery cable.
  9. Reinstall the fuel tank filler pipe cap.
  10. Inspect for fuel leaks.
  11. Turn the ignition switch ON for 2 seconds.
  12. Turn the ignition switch OFF for 5 seconds.
  13. Turn the ignition switch ON .
  14. Check for fuel leaks.

Oct 26, 2010 | 2002 Cadillac Deville

1 Answer

how do I change a fuel pump on a 2002 yukon


Need to know the size of the engine but this is a picture of what it is....


Posting the rest of the directions for you:


1cf4b2b.gif
Illustrating fuel pump and sending unit sensor (3) on 2000-2004 4.8L, 5.3L, 6.0L Engines

Removal & Installation
  1. Before servicing the vehicle, refer to the Precautions section.
  2. Remove or disconnect the following:
    • Negative battery cable
  3. Relieve the fuel system pressure.
  4. Drain the fuel tank.
  5. Remove or disconnect the following:
    • Fuel tank

    WARNING Do not handle the fuel sender assembly by the fuel pipes. The amount of leverage generated by handling the fuel pipes could damage tool Joints.

  6. Disconnect the fuel and evaporative emission (EVAP) lines from the fuel tank module.
  • Fuel sender assembly retaining ring using a fuel tank sending unit wrench. Remove the fuel sender assembly and the seal. Discard the seal.
  • Note the position of the fuel strainer on the fuel sender. Support the fuel sender assembly with one hand and grasp the strainer with the other hand. Pull the strainer off the fuel sender. Discard the strainer after inspection. Inspect the strainer. Replace a contaminated strainer and clean the fuel tank.
  • Fuel pump electrical connector
  • Electrical connector retaining clip from the fuel level sensor
  • Sensor electrical connector from under the fuel sender cover
  • Fuel level sensor retaining clip
  • Squeeze the locking tangs and remove the fuel level sensor.
  • Remove the fuel pressure sensor.
  • To install:
    1. Install or connect the following:
      • Fuel pressure sensor
      • Fuel level sensor
      • Sensor retaining clip
      • Electrical connector to the fuel level sensor
      • Electrical connector retaining clip to the fuel level sensor
      • Fuel pump electrical connector

      NOTE Always install a new fuel strainer when replacing the fuel tank fuel pump module.

      • New fuel strainer in the same position as noted during disassembly. Push the strainer on the bottom of the fuel sender until the strainer is fully seated.
      • New seal on the fuel tank

      NOTE The fuel pump strainer must be in a horizontal position when the fuel sender is installed in the tank. When installing the fuel sender assembly, assure that the fuel pump strainer does not block full travel of the float arm.

      • Fuel sender assembly into the fuel tank
      • Fuel sender assembly retaining ring
      • Fuel tank. Install the fuel tank strap attaching bolts. Tighten the bolts to 30 ft. lbs. (40 Nm).
    2. Refill the fuel tank. Install the fuel filler cap. Connect the negative battery cable.
    3. Turn the ignition ON for 2 seconds.
    4. Turn the ignition OFF for 10 seconds.
    5. Turn the ignition ON.
    6. Inspect for fuel leaks.

    Sep 13, 2010 | 2002 GMC Yukon Denali

    1 Answer

    replace fuel pump for 2002 gmc sierra 2500


    First...this is where the pump is (gas tank) on the engines listed:

    6f9f9d7.gif

    Illustrating fuel pump and sending unit sensor (3) on 1999-2005 4.8L, 5.3L, 6.0L Engines


    Removal & Installation
    1. Before servicing the vehicle, refer to the Precautions section.
    2. Remove or disconnect the following:
      • Negative battery cable
    3. Relieve the fuel system pressure.
    4. Drain the fuel tank.
    5. Remove or disconnect the following:
      • Fuel tank
    8e4564e.gif
    WARNING Do not handle the fuel sender assembly by the fuel pipes. The amount of leverage generated by handling the fuel pipes could damage the joints.

    • Fuel sender assembly retaining ring using a fuel tank sending unit wrench. Remove the fuel sender assembly and the seal. Discard the seal.
  • Note the position of the fuel strainer on the fuel sender. Support the fuel sender assembly with one hand and grasp the strainer with the other hand. Pull the strainer off the fuel sender. Discard the strainer after inspection. Inspect the strainer. Replace a contaminated strainer and clean the fuel tank.
    • Fuel pump electrical connector
    • Electrical connector retaining clip from the fuel level sensor
    • Sensor electrical connector from under the fuel sender cover
    • Fuel level sensor retaining clip
  • Squeeze the locking tangs and remove the fuel level sensor.
  • Remove the fuel pressure sensor.
  • To install:
    1. Install or connect the following:
      • Fuel pressure sensor
      • Fuel level sensor
      • Sensor retaining clip
      • Electrical connector to the fuel level sensor
      • Electrical connector retaining clip to the fuel level sensor
      • Fuel pump electrical connector
      NOTE Always install a new fuel strainer when replacing the fuel tank fuel pump module.

      • New fuel strainer in the same position as noted during disassembly. Push the strainer on the bottom of the fuel sender until the strainer is fully seated.
      • New seal on the fuel tank
      NOTE The fuel pump strainer must be in a horizontal position when the fuel sender is installed in the tank. When installing the fuel sender assembly, assure that the fuel pump strainer does not block full travel of the float arm.

      • Fuel sender assembly into the fuel tank
      • Fuel sender assembly retaining ring
      • Fuel tank. Install the fuel tank strap attaching bolts. Tighten the bolts to 30 ft. lbs. (40 Nm).
    2. Refill the fuel tank. Install the fuel filler cap. Connect the negative battery cable.
    3. Turn the ignition ON for 2 seconds.
    4. Turn the ignition OFF for 10 seconds.
    5. Turn the ignition ON.
    6. Inspect for fuel leaks

    Oct 25, 2009 | 2002 GMC Sierra 1500

    1 Answer

    where is the fuel pump in a 3.4 2000 chevy impala? is it hard to replace?


    Please don't forget to rate!!!!

    Pump is in the tank and here is the procedures to do the job:

    Fuel Pump Removal & Installation To Remove:
    1. Relieve the fuel system fuel pressure.
    2. Drain the fuel tank from the filler neck as much as possible.
    3. Raise and safely support the vehicle.
    4. Loosen the clamp and remove the filler hose from the fuel tank.
    5. Disconnect the fuel and EVAP quick-connect fittings at the fuel tank.
    6. Remove the exhaust pipe hangers and allow the exhaust system to drop slightly.
    7. Separate the EVAP fresh air line at the splice.
    8. Remove the fuel tank shield.
    9. Support the fuel tank with a suitable jack.
    10. Remove the two bolts securing the fuel tank straps.
    11. Lower the fuel tank from the vehicle.
    12. Disconnect the electrical connectors from the fuel pump assembly.
    13. Clean the fuel pipe connections with compressed air to prevent contamination during removal.
    14. Disconnect the quick-connect fittings at the fuel sender assembly.
    15. Remove the fuel sender retaining ring and remove the fuel sender assembly. The modular fuel sender assembly will spring-up when the snap ring is removed.
    To Install:
    CAUTION
    Be careful not to fold or twist the fuel inlet strainer when installing the fuel sender assembly, this will restrict fuel flow. Also, make sure the float arm is able to move freely.
    1. Place a new fuel sender assembly seal on the tank and install the fuel sender assembly.
    2. Holding the fuel sender in place and install the retaining ring.
    3. Connect the quick-connect fittings at the fuel sender assembly.
    4. Connect the electrical connectors.
    5. Place the fuel tank on a suitable jack and raise it in position under the vehicle.
    6. Install the fuel tank strap bolts. Tighten the bolts to 35 lb ft (48 Nm).
    7. Install the fuel tank shield.
    8. Connect the fuel and EVAP quick-connect fittings at the fuel tank.
    9. Connect the EVAP fresh air hose at the splice.
    10. Install the fuel tank filler hose to the fuel tank.
    11. Raise the exhaust and install the exhaust pipe hangers.
    12. Lower the vehicle.
    13. Add fuel and install the fuel filler pipe cap.
    14. Connect the negative battery cable.
    15. Perform the following to pressurize the fuel system;
      • Turn the ignition ON, for 2 seconds.
      • Turn the ignition OFF, for 10 seconds.
      • Turn the ignition ON.
    16. Inspect the fuel system fuel leaks.

    Jul 16, 2009 | 2000 Chevrolet Impala

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