Mercedes And Fuel Tank: 7 Answers You Should Know

Mercedes-Benz is one of the most elegant, and performance-oriented cars on the auto market today. Many drivers regard Mercedes as the industry leader due to the revolutionary vehicles it has produced.

One of the reasons why people choose Mercedes is its durability. Notwithstanding these remarks, Benz fans have pointed out a number of faults, such as the fuel tank issue. In this article, we’ll talk about Mercedes fuel tank problems.

The Mercedes Benz is one of the most well-known passenger cars. It’s popular because of its luxury, performance, and durability. Mercedes’ engines are excellent, although they are not among the most fuel-efficient cars.

The fuel tank problem, which some perceive to be one of Mercedes’ flaws, is not a common problem. Some Mercedes-Benz vehicles, such as the CLA250, A220 4-Matic, and AMG A35 4-Matic, are noted for being less fuel-efficient.Mercedes and fuel tank: 7 Answers you should know

There could be various reasons why your Mercedes’ fuel tank is failing, and there are warning signals to look for. Damaged fuel pumps, air in the fuel tank, and broken pipes are all common problems.


What is the fuel tank capacity of the Mercedes?

The capacity of Mercedes’ fuel tank varies depending on the model. A car’s average tank size can hold between 45 and 65 litres of fuel.

The Mercedes-Benz E-Class, on the other hand, has a fuel tank capacity of 59–80 litres. The Mercedes C-Class has a fuel tank capacity of 66 litres.

Check your vehicle’s owner’s manual to know the capacity of your Benz fuel tank.

How do you know you have a bad fuel tank?

There are signs that your tank’s fuel tank is failing. It’s unusual for a fuel pump to stop working without notice. You can typically detect a worn fuel pump.

Some frequent indicators of a faulty fuel tank are listed below.

  • A faulty fuel pump

The fuel pump is responsible for transferring fuel from the fuel tank to the engine. The fuel pump must be powerful enough to deliver fuel under high pressure.

Fuel injectors will not be able to spray the necessary amount of fuel into the combustion chamber if the pressure is low, resulting in a loss of power.

At low speeds, a malfunctioning fuel pump may not cause problems, but when you need to accelerate quickly, you may be disappointed.

While the fuel pump on any vehicle can fail, the fuel pump relay may be the most serious issue.

The fuel pump relay is normally controlled by the ignition or powertrain control module, and when activated, it supplies current to the fuel pump, allowing it to operate. When you turn on the ignition, the fuel pump relay delivers enough power to keep your car running until your fuel pump is set.

The fuel pump relay is turned off when the fuel pump starts operating. It won’t turn off until you turn off your car. The fuel pump relay forces the fuel pump to stop once the vehicle is turned off.

Problems with your fuel pump are more common and can give the impression that it has failed. Your relay, rather than the pump, may need to be changed in many circumstances.

Electrical power surges that increase the voltage are the most common reason for a fuel pump relay failing.

  • Hard starting

It is not always the case that a faulty alternator or a dead battery causes your car to not start. It may be difficult to start the car if the fuel tank is damaged. Your fuel pump may be having trouble delivering adequate fuel.

You’ll have difficulties starting your car if the fuel pump can’t transport gas from the tank to the engine. Because the pump can’t get enough gas through, the car will struggle to start and run. When a worn pump loses its pressure, the engine runs out of gas.

  • A decrease in power

The combustion of air and fuel provides power to a vehicle’s engine. The car moves because the energy produced by combustion is transmitted to the wheels.

The engine’s job is to accomplish this task as efficiently as possible, over and over again. The engine, however, loses power for a variety of reasons, and it could lead to a performance decrease.

The engine will not be able to work at its best if the fuel filter becomes clogged and the fuel does not reach the engine chamber in a sufficient quantity.

When accelerating, you’ll notice a decrease in power and, on rare occasions, jerks. Fuel pump issues manifest as a loss of power, misfires, or slowed acceleration when driving.

It’s likely that your fuel pump is the problem if your car lacks power when driving up hills. Under pressure, the engine consumes more gasoline, just as it does at higher speeds. You’ll lose power if the pump isn’t working properly.

  • Surging Power

If the pump is putting too much fuel into the engine, you’ll notice power spikes and a misfire while driving. If your car is surging when you speed, you should solve the issue as soon as possible.

When a car accelerates, there are reasons for the increase. It’s possible that fuel is not getting to your engine in the correct order, or that faulty torque converters are to blame. Finally, if the intake system loses power, misfiring may occur.

  • Air in the fuel tank

The presence of air in your tank could indicate a problem with your EVAP system. When there is air in a gas tank, the vapors may not be released back to the engine.

The air might induce a buildup of pressure in the tank. It can cause stalling and eventually disable your car’s ability to start.

Mercedes fuel tank pressure sensor

The fuel tank pressure (FTP) sensor is a crucial component of the evaporative emissions control system, which captures unburned gasoline vapors and reintroduces them into the fuel system.

The fuel tank pressure sensor is a component of the gasoline pump system that is positioned on top of or inside the tank. It reads pressure in the fuel system to detect evaporative leaks, such as a loose or malfunctioning gas cap. It is a part of the evaporative emissions system.

The fuel tank pressure sensor can be found inside or on top of your fuel tank, near the rack unit that holds the fuel pump in place.

A reference voltage cable from your car’s computer, a ground wire, and a voltage return wire to the powertrain control module are all included in the pressure sensor.

So, if your fuel tank pressure sensor isn’t working, all you have to do is look at the wires to see if it’s the sensor or something else.

What happens when the fuel tank pressure sensor goes bad?

The fuel tank pressure (FTP) sensor is a central component of the evaporative emissions management system, which is meant to trap and reintroduce unburned gasoline vapors back into the fuel system.

The fuel tank pressure sensor is in charge of detecting fuel system defects, such as evaporative leaks or a faulty fuel cap seal.

When the FTP detects a leak in the fuel tank or system, it notifies the ECU, which causes the “Check Engine” light to illuminate.

Signs of a faulty fuel tank pressure sensor include:

  • The Check Engine Light comes on.

A Check Engine light may illuminate for a variety of reasons. This engine light is a critical component of your vehicle’s onboard diagnostic system.

When your vehicle’s computer detects a problem, it will illuminate the warning light. A damaged seal on the fuel cap could be the culprit, but it could also indicate a fuel system leak.

The light might be triggered by a malfunctioning gas cap that allows fuel vapors to escape into the atmosphere.

  • The vehicle will not start.

The fuel tank pressure sensor could be the source of your vehicle’s difficult starting. Hard starting is one of the early signs of a fuel rail sensor malfunction.

A malfunctioning fuel rail sensor may transmit an incorrect signal to the computer, causing the engine to struggle to start. It may take a few more cranks to start the engine than usual, or it may not start at all in severe circumstances.

  • The vehicle is stalling.

As the fuel rail pressure sensor deteriorates, engine stalling is a possibility. Your engine will stall while you’re driving. While idling, it could potentially stall. Driving will be quite tough as a result.

A defective fuel tank pressure sensor could be to blame if the car stalls unexpectedly. The fuel tank pressure sensor may be sending inaccurate signals.

  • Acceleration is slow.

Poor acceleration is mostly caused by fuel delivery and sensor difficulties. If you have sluggish acceleration, you may have a faulty fuel pressure sensor.

Because the sensor provides erroneous data, the engine control unit is unable to appropriately convey the signal to the fuel system.

Why did the fuel tank pressure sensor fail?

The fuel tank pressure sensor can be damaged by a variety of factors. The main reasons, however, are excessive exposure to corrosive gasoline fumes, and extreme temperatures,

If the fuel tank is choked, fuel can overflow into the charcoal canister and other overflow lines, causing the sensor to fail.

Can you bypass a fuel tank pressure sensor?

It is uncertain yet possible to bypass a fuel tank’s pressure. You can use an oscilloscope if you have one. The oscilloscope plots the various signal voltages on a graph.

When electrical components or systems in a car are tested, electronic signals are produced. An oscilloscope will capture these electrical signals in graphs, allowing users to measure and comprehend what’s going on in a system.

The pressure sensor can be bypassed by simply plugging it in. However, a check engine light will almost surely appear as a result of the repair. The pressure sensor ensures that the fuel tank does not leak toxic fuel vapors into the atmosphere.

When the pressure reaches a specific level, the bypass valve opens. As a result, some fuel is returned to the tank. Also, the pressure in the system will be lowered.

By attaching the sensor wire to an oscilloscope, you may figure out what signal is being delivered to the onboard computer.

What happens when a vent valve goes bad?

The EVAP system includes the vent valve. It regulates the amount of outside air that enters and exits the charcoal canister.

The engine computer is in charge of the vent valve (PCM). The vent valve is normally open. It closes when the engine computer checks for leaks in the EVAP system.

The Check Engine light will appear on the dash if a leak in the EVAP system is detected, and the trouble code associated with the malfunction will be logged in the engine computer.

Problems with the vent valve

The EVAP vent valve is usually found underneath the vehicle, near or at the charcoal canister under the fuel tank, Rough Idle, in most cars.

The vehicle will not run smoothly if the purge valve is not opened properly. It will operate at an irregular rate while driving, especially at low speeds. A faulty purge valve can potentially cause a vacuum leak, resulting in a harsh idle.

When the EVAP vent valve fails, fresh air cannot enter the EVAP system, which can have a detrimental impact on the system’s performance. When a vent valve fails, it usually causes one of the following problems:

The check engine light is illuminated.

An illuminated check engine light is one of the earliest signs of an EVAP vent valve malfunction. The Check Engine Light will illuminate if the computer detects a problem with the EVAP vent valve signal.

Additionally, the pressure in the vehicle’s fuel tank may not be able to be vented and released efficiently if the EVAP vent valve fails.


The Mercedes- Benz is a high-end car. The fuel tank problem is not common. Before the fuel tank failed, a variety of factors could have triggered it. If you detect any of the issues mentioned in this post, you should address them right away.


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