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Mercedes-Benz of Stevens Creek

Mercedes-Benz Sprinter Fuel System Problems - How To Troubleshoot and Fix

Your Mercedes-Benz Sprinter's fuel system is its lifeblood, responsible for delivering fuel from your tank to your engine. It comprises a fuel tank, fuel pump, fuel filter, and fuel injectors - all performing in tandem to manage a combustion process that mixes fuel with air before being ignited and made into the exhaust.

In a nutshell, your fuel pump sends fuel from the gas tank to the engine. In between, fuel navigates through the fuel lines in your vehicle's undercarriage, bypassing a fuel filter that grinds out dirt, debris, and other contaminants. Once fuel bypasses your fuel filter, it travels to the engine to rev up your piston and gears.

On occasion, heavy wear and tear and extended driving can compromise your fuel system.

Keep reading to learn more about Mercedes-Benz Sprinter fuel filter problems, Mercedes-Benz Sprinter fuel pressure problems, and Mercedes-Benz Sprinter fuel pump problems.

The Fuel Filter

Your fuel filter is responsible for screening dirt, dust, and small particles from the fuel before it reaches your engine. Any stray debris or particulates can cause long term engine damage. It is a constant magnet for contaminants. If there is too much blockage, only a limited amount of fuel will be able to pass through to the filter, putting your fuel pump into overdrive.

What Are Symptoms of a Defective Fuel Filter?

Some signs of a defective fuel filter including engine misfires, sudden stalling, and worsening fuel economy. Dirty filters cause fuel restrictions, preventing extra fuel from reaching your engine at higher speeds.

How do I Replace My Mercedes-Benz Sprinter's Fuel Filter?

Changing your vehicle's fuel filter is a moderately challenging process that only takes a few steps.

  1. Turn off your vehicle's engine.
  2. Disable the electric fuel pump by removing it from the fuel box. This will reduce fuel line pressure.
  3. Disconnect the fuel lines from the filter.
  4. Remove your old filter and mount the new filter in the old filter's place.
  5. Replace your fuel pump's fuse in the fuse box.
  6. Turn on the engine and inspect the filter for any leaks.

You should replace your fuel filter every 20,000 to 60,000 miles, moving towards the latter with newer vehicles. Make sure to get a high quality OEM Mercedes-Benz fuel filter when it is time to replace your old one.

The Fuel Pressure and Fuel Pressure Regulators

Fuel pressure regulators help your vehicle monitor the flow of fuel through your system. It works by using a diaphragm, which controls a bypass valve that opens and closes depending on driving conditions, supplying the engine with a steady dose of fuel.

What Are Some Symptoms of Poor Fuel Pressure?

Defective fuel pressure regulator symptoms include reduced fuel economy, leaking fuel, engine misfires, and blackened spark plugs. Poor acceleration is also a culprit, especially when driving uphill. The best way to test for a defective fuel pressure regulator is by using a fuel pressure gauge, which you can do easily from your home or garage.

How do I Replace My Mercedes-Benz Sprinter's Fuel Pressure Regulator?

Replacing your Mercedes-Benz Sprinter's fuel pressure regulator requires parking your vehicle, disconnecting your battery, removing the engine cover to access the fuel pressure sensor, and accessing the fuel rail to remove the fuel pressure regulator before installing the new one.

After installing the new fuel pressure regulator, the battery is reconnected and the engine turned on before checking for leaks using a combustible gas detector.

The Fuel Injector

Located by your engine's intake manifold near the intake valve, your Mercedes-Benz Sprinter's fuel injectors use a series of nozzles to feed fuel to your engine, all programmed by your vehicle's computer. It uses gas mixed with air to optimize the air-to-fuel ratio, which varies based on driving conditions.

What Are Some Symptoms of A Defective Fuel Injector?

The number one problem associated with fuel injectors is clogging as a result of lack of maintenance. Some symptoms associated with fuel injectors include a loss of power, pungent fuel smell, and a check engine light. As a general rule, you should inspect them every 100,000 miles.

How do I Replace My Mercedes-Benz Sprinter's Fuel Injector?

For this process, you will need a pair of safety goggles.

Relieve fuel system pressure by locating your fuse box's fuel pump, starting the vehicle, and pulling the fuse out. Disconnect the fuel rail by removing its hold-down screws and bolts. Disconnect the fuel injectors by removing the wire that holds each fuel injector wiring plug in place. Yank the fuel injector out using a fuel injector puller, sliding it under your injector housing's lip carefully. Mount a new fuel injector in, completing all of the steps above in reverse order. Don't forget to lubricate your new fuel injector seals. Make sure to get an OEM Mercedes-Benz fuel injector when it comes time to replace your old one. 

The Fuel Pump

Think of a fuel pump as your Mercedes-Benz Sprinter's heartbeat. Located in your gas tank, it helps deliver fuel to your engine based on vehicle output. A pump draws fuel from your fuel tank and directs it to your engine and carburetor using positive electrical pressure.

What Are Some Symptoms of A Defective Fuel Pump?

The most common symptoms of a defective fuel pump are whining or howling noises coming from the gas tank, a sudden loss of power, check engine light activation, and loss of fuel economy.

These symptoms are due to a lack of proper pressure of fuel hitting your internal combustion engine. Inconsistent gas volume, especially with sudden stops or gas pedal pumping, can cause engine misfires. Lack of fuel to the engine also compromises fuel economy.

How Do I Check For a Defective Fuel Pump on My Mercedes-Benz Sprinter?

Troubleshooting, diagnosing, and repairing a defective fuel pump is an easy process.

Please perform the following steps to check for a defective fuel pump. You will need a fuel pressure tester for this task, which you can purchase from the Mercedes-Benz national store.

  1. Open your Mercedes-Benz Sprinter's hood and remove the engine cover.
  2. Connect your fuel pressure tester to the vehicle by lifting off the Schrader valve cap and locating your fuel rail's fuel pressure port.
  3. Turn the car on and record the pressure reading.
  4. Acceptable pressure ranges include 47 – 55 PSI on idle and 54 – 61 PSI with a disconnected vacuum hose.

If pressure readings are not acceptable, it may be time to replace your fuel pump. This process involves disconnecting all fuel hoses, emissions hoses, and connections and removing your pump assembly's retainer ring.

How do I Replace My Mercedes-Benz Sprinter's Fuel Pump?

Please follow the steps below to replace your Mercedes-Benz Sprinter's fuel pump. For this, you will need a pair of safety goggles.

  1. Drain your fuel pump to prevent fuel and vapor leaks.
  2. Disconnect your negative battery cable.
  3. Reach your integrated floor access cover by disconnecting your negative battery cable and removing rear seating.
  4. Disconnect all fuel hoses, emissions hoses, and connections from the pump assembly.
  5. Remove your pump assembly's retainer ring and the fuel pump.
  6. Place your replacement fuel pump in the same spot, tightly connecting the seal ring.
  7. Re-mount all connections, fuel hoses, emissions hoses, and rear seat floor and seats.

Reconnect your negative battery cable and perform a test drive to check for defective fuel pump symptoms, including stalling and loss of power. Make sure you get a new OEM Mercedes-Benz fuel pump when it is time to replace your old one. 

A Word About Check Engine Lights

When your check engine light turns on, it may be a sign of a fuel system problem. However, it is triggered and associated with hundreds of diagnostics codes, so it is not a sure sign your fuel system is affected. Do-it-yourselfers can use a diagnostic scanner to read Mercedes-Benz Sprinter fault codes with a certified Mercedes-Benz technician to assist as a last resort.