How to Depressurize a Fuel System | 7 Methods Explained by Expert

How to Depressurize a Fuel System

It is necessary to effectively depressurize the fuel system because it will minimize the risk of an explosion even if there is a fire. For example, if the fuel system is pressurized and there is a fire, but the fuel system depressurizes, it would be much safer. 

Fuel systems can become depressurized in various ways ranging from a positive pressure relief valve to a pressure switch. In ultimate conditions, it may be necessary to depressurize a fuel system. It does for safety reasons. This blog will look at the steps involved in depressurizing a fuel system and things you need to be aware of them.

Process of Depressurizing a Fuel System

How to Depressurize a Fuel System

The process of depressurizing a fuel system is relatively simple. If you want to pump down the fuel level in your RV’s fuel tank because you’re going to be taking a tour that requires long periods at a low altitude, then follow these directions: 

  • Make sure that the tank is empty. Close the fuel valve. 
  • Locate the drain on the bottom of the tank. Remove the cap. 
  • Put a hose into the drain. 
  • Attach the hose to a small hand pump. 
  • Ensure that the hand pump primes to enable the tank to empty fully.
  • Sustained steps four and five until you can no longer pump fuel from the tank.

How to Depressurize a Fuel System

How to Depressurize a Fuel System

Seven Ways to Depressurize A Fuel System:

Method 1

The fuel system depressurizes by an engine vacuum. It can defeat by opening a fuel pump fuse using a paperclip or safety pin to attach the end of the fuse wire to the ground. However, this will stop your fuel pump from running, so you must pump it by hand if you need fuel. Opening the fuse on a car with an electric fuel pump would not stop the pump, but it would prevent it from pressurizing the fuel system. You may have to remove a fuse to stop the pump or disconnect the pump if it can remove.

Method 2 

The quickest way to depressurize the fuel system is to open the drain valve at the bottom of the fuel tank and allow the fuel to run out until the flow becomes just a trickle. There is no significant pressure in any fuel line that could seriously injure or kill you. A far more dangerous situation is running out of fuel on the highway. 

Method 3

The fuel system should only depressurize if the tank is an emergency. If depressurizing is necessary, the emergency shutoff valve and the emergency valve must be closed. The fuel tanks should depressurize. It does by turning the fuel shutoff valve open. The tank will take a few minutes to depressurize.

Method 4

Depressurizing the fuel system is quite laborious, and there’s no other way of reducing the pressure to zero. But, there is a principle to make it simpler. All you need to do is lift the rear of the car and secure it with the help of a jack. Two of us should hold the car’s seat to ensure it doesn’t fall. This way, we can depressurize the system.

Method 5

One way is to remove the car’s fuel filler cap, turn off the engine, and let the gas out. Another way is to connect an air hose into the vehicle’s fuel system. With this method, the air is blown in through one nozzle while gas pushes out. A third way is to have a machine shop remove the pressure from the gas tank by using safety devices found on their equipment.

Method 6

You can use a rod tool or a rodless valve depressurize. Rodless valve depressurizes are usually used more often and conveniently, but rods are faster. Before depressurizing the system, you need to shut off the airflow and ensure that the vehicle turns off. The rod or the rodless valve depressurize should insert into the fill neck, or if you’re using a rod, it should insert into the fill port. You can then remove the pressure and begin emptying the fuel system.

Method 7

One method is to wait for the engine to cool down. Then, start the engine and drive it until the tank is empty. When that does, open the fuel pump valve and then close it. It will depressurize the fuel lines.  

Another way is to wait for the engine to cool down and use a wire to pull the fuel pump relay. Use a torch to see inside the fuel vessels.

Frequently Asked Questions

How Do You Release Pressure from A Fuel System?

The actual mechanism of the release can release the pressure in a fuel system. If it is a surge tank, one can use a valve to regulate the flow of fuel that would flow into the tank. In this case, when pressure applies to the tank, it will force energy out through its openings. 

How Do I Reduce Fuel Pressure Without Starting My Car?

The way to reduce fuel pressure without starting your car is by removing the negative lead of the coil. It will stop the flow of electricity that sparks the fuel pump and halt its gasoline expelling. If you are not an expert in this area, it is advised not to touch any wires without first contacting a mechanic.

How Do You Bleed Air From A Fuel Line?

The fuel line disconnects from the engine, and the inside bled by using compressed air with a nozzle. It ensures that all air removes from the lines before reconnecting.

How Can You Check Your Fuel Pressure Without A Gauge?

First, you’ll need to find the Schrader valve on your gas tank. With the car turned off and without touching the ground, depress the Schrader valve with one hand. When gas starts to flow out, use your other hand to count how long it takes for the pressure to build up. It should take 30 seconds or less before the fuel starts flowing.


Many boaters don’t realize that removing the air from the fuel system is as vital as adding fuel to the tank. Both steps are essential to ensure that the engine gets all the energy it needs to run correctly.  

Sometimes, however, it’s necessary to depressurize the fuel system to prevent something from happening that could damage your boat or hurt someone on board. Here are the steps you’ll want to follow to depressurize the fuel system.