Fuel Line Replacement: Is It Worth The Hassle?

Replacing a vehicle's fuel lines can be a complex task, and it is important to approach it with caution. Fuel lines are an essential component of a vehicle's fuel system, delivering fuel from the tank to the engine. Over time, fuel lines can deteriorate and leak, leading to hazardous situations. Corrosion is a common issue with metal fuel lines, often initiated by abrasive materials removing the protective paint or coating. This can be caused by debris from the road or mounting brackets. As vehicles age, the likelihood of fuel line leaks increases, and it is crucial to address this issue promptly to prevent accidents.

Is Replacing Fuel Lines Hard?

Fuel line corrosion

To prevent fuel line corrosion, it is essential to use fuel additives that protect the fuel system against corrosion. These additives form a protective film on metal surfaces, shielding them from corrosive substances. For diesel engines, a Super Diesel Additive can be used, while Petrol Stabilizer or Injection Cleaner is recommended for petrol engines when stored for extended periods.

If you notice surface rust on your fuel lines, there are several remedies you can apply. One method is to apply heavy grease with a paintbrush, as the oil will creep into the lines and slow down the corrosion process. Another approach is to use a Scotch-Brite pad to remove loose rust, followed by degreasing the lines with brake cleaner, and then applying grease or oil. Rust converter paint can also be used, but it may deteriorate under sunlight.

For internal rust in steel fuel lines, cleaning with a long bottle brush, hot water, and soap is recommended. Alternatively, phosphoric acid can be used to soak and dissolve the rust, but this will also remove the plating, requiring replating afterward. It is also important to address the source of the rust, such as a poorly sealed fuel tank, to prevent recurrence.

In some cases, replacing the fuel lines may be necessary. Corrosion can lead to fuel leaks, and attempting to repair or reuse high-pressure fuel lines can be dangerous and is not recommended. It is essential to prioritize safety and follow the vehicle manufacturer's guidelines for fuel line replacement.

Fuel hose replacement

Overview

Fuel hoses come in many different locations on vehicles. On older vehicles, there are steel lines from the fuel tank to the carburettor or injectors of a fuel system. Some older vehicles have short fuel hoses that connect the steel line to the fuel pump, fuel tank, and carburettor. These hoses tend to weaken and split over time, causing fuel to leak out.

From 1996 onwards, vehicles have become more sophisticated, using more advanced fuel injection systems. All vehicles that operate on gasoline have a supply line, return line, and a vapour line. These lines are plastic and crack over time as they wear out.

There are several forms of fuel hoses: rubber with adhesive liners, plastic or carbon fibre, or steel or aluminium.

Step 1: Verify the Condition of the Fuel Hose

Firstly, check for leaking fuel. Using a flashlight and a combustible gas detector, check for any leaking fuel in the engine compartment. Also, check for any fuel leaking on the supply, return, or vapour hoses.

Step 2: Remove the Fuel Hose

Make sure you have all the necessary tools and materials before starting the work. You will need:

• A flathead screwdriver
• A fuel hose quick disconnect kit
• Fuel-resistant gloves
• A fuel transfer tank with a pump
• A ratchet with metric and standard sockets

Then, follow these steps:

• Park your vehicle on a flat, hard surface and put it in park (for automatics) or in 1st gear (for manuals).
• Place wheel chocks around the front tires and engage the parking brake.
• Use a floor jack to lift the vehicle at its specified jacking points until the wheels are off the ground.
• Place jack stands under the jacking point locations and lower the vehicle onto them.
• Install a nine-volt battery saver into your cigarette lighter to keep your computer live and keep your settings current.
• Open the vehicle's hood and disconnect the battery. Take the ground cable off of the battery's negative post to disable the power to the ignition and fuel system.
• Locate the fuel hose that is damaged or leaking. Remove the hose clamps that hold the fuel hose in place.
• Place a small drip pan under the fuel hose and pull it off the attaching fuel line, fuel pump, or carburettor.
• Clean the surface the fuel hose attaches to using a lint-free cloth.

Step 3: Install the New Fuel Hose

• Place new hose clamps around the new fuel hose. Be sure the clamp is installed at the proper tightness.
• Install the new fuel hose onto the fuel pump, fuel line, or carburettor. Tighten the new hose clamps and secure the hose.
• Do not use old hose clamps as the clamping force will not hold when tightened, causing a leak.

Step 4: Check for Leaks

• Reconnect the ground cable to the battery's negative post and remove the nine-volt battery saver.
• Tighten the battery clamp and ensure the connection is good.
• Turn the ignition key on. Listen for the fuel pump to activate and turn off the ignition after the fuel pump stops making noise.
• Cycle the ignition key on and off 3 to 4 times to ensure all the fuel lines are full of fuel.
• Use a combustible gas detector to check all the connections for any leaks. Sniff the air for any fuel odours.

Step 5: Lower the Vehicle and Test Drive

• Raise the vehicle with a floor jack and remove the jack stands.
• Lower the vehicle so that all four wheels are on the ground and remove the wheel chocks.
• Drive the vehicle around the block and go over different bumps, allowing the fuel to slosh around inside the fuel lines.
• Monitor the dashboard for the fuel level and for any engine lights to appear.

High-pressure fuel lines

When replacing high-pressure fuel lines, it is important to use the correct tubing and fittings designed specifically for high-pressure CNG fuel systems. Traditional tubing and fittings used in gasoline and diesel vehicles are not suitable for these systems. The tubing must be routed in a protected area to avoid exposure to road debris, moisture, hot components, and rotating parts.

In terms of the replacement process, it is recommended to replace the entire fuel line rather than splicing in a new line. This is because the rest of the line may not be far behind in terms of deterioration. Modern rubber hoses can be used for repairs and are made of better rubber, reinforced to handle the pressure of modern injection systems, and designed to last.

When working with tubing, it is important to incorporate relief bends into the layout as the size of the tubing can vary with temperature changes. Additionally, when recreating bends in the tubing, proper measurement, cutting, deburring, and use of bending tools designed for stainless steel tubing are crucial.

Fuel injection systems

The fuel injection system measures the amount of air intake into the engine and supplies the required amount of fuel for combustion. The fuel injection rate is controlled by an ECU (engine control unit) which calculates the amount of fuel to be injected based on signals from the sensor that detects the amount of air intake. The ECU also controls the length of time the fuel injection valves (injectors) stay open.

There are two main types of control for multi-port systems: the fuel injectors can all open at the same time, or each one can open just before the intake valve for its cylinder opens (this is called sequential multi-port fuel injection). Sequential fuel injection allows the system to respond more quickly to sudden changes.

The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open, which is called the pulse width and is also controlled by the ECU.

There are two representative methods for detecting the amount of air intake: the mass flow method and the calculation method. The mass flow method directly measures the amount of air intake into the engine using an airflow meter. The calculation method estimates the amount of air intake based on the speed of engine rotation, air temperature, and the pressure detected at the air intake pipe.

The injectors are one of two types, depending on the injection system. The first system uses continuous injection where the fuel is squirted into the inlet port all the time the engine is running. The other popular system is timed injection (or pulsed injection) where the fuel is delivered in bursts to coincide with the induction stroke of the cylinder.

All modern petrol injection systems use indirect injection, where the petrol is injected into the inlet manifold or inlet port rather than directly into the combustion chamber. This ensures that the fuel is well mixed with the air before it enters the chamber.

Some cars have multi-point fuel injection where each cylinder is fed by its own injector. It is more common to have single-point injection where a single injector feeds all the cylinders, or to have one injector for every two cylinders.

Fuel line safety

Identifying a Fuel Line Leak

It is crucial to be able to spot the signs of a fuel line leak, as it is a potentially serious issue. Some warning signs include:

• A strong smell of gasoline in or around your vehicle.
• Visible fuel leaks, which can leave puddles on the road or small drops under your vehicle.
• A hissing sound, similar to air escaping from a tire, coming from the engine when idle or turned off.
• Reduced engine performance, including misfires, unexpected power loss, and rough idling.
• The check engine light is on, which could indicate a fuel leak if accompanied by other signs such as a gasoline smell or hissing noise.

Causes of Fuel Line Leaks

Understanding the causes of fuel line leaks can help you take preventive measures:

• Corrosion: Exposure to moisture, salt, and road debris can cause fuel lines to rust and leak over time.
• Aging and wear: Older vehicles' fuel lines, especially those made of metal or rubber, are more prone to wear and leakage.
• Permeation: In soft and flexible hoses, fuel can soak into the hose over time, weakening it and leading to cracks and leaks.
• Physical damage: Accidents, road debris, or improper handling during maintenance can puncture and damage fuel lines.
• Vibration: Engine or driving vibrations can wear out fuel lines, causing cracks or weakened connections.
• Manufacturing defects: In some cases, manufacturing issues or low-quality materials can result in weakened fuel lines.

Preventive Measures and Maintenance

To ensure fuel line safety and reduce the risk of leaks, consider the following:

• Regular inspections: Have your fuel lines inspected regularly, especially if you notice any signs of corrosion or damage.
• Proper maintenance: Keep your vehicle well-maintained and handle fuel lines with care during repairs or modifications.
• Protect from corrosion: Take measures to protect metal piping from corrosion by using appropriate coatings or treatments.
• Avoid flexible fuel hoses: Do not replace long runs of hard lines with flexible fuel hoses, as they can be prone to damage and difficult to seal properly.
• Use approved parts: When replacing fuel lines, use approved parts that meet EPA, SAE, and CARB standards for permeation.

Remember, fuel line safety is critical to prevent fires and other hazardous situations. If you suspect a fuel leak, pull over to a safe location, turn off the engine, and contact a qualified mechanic for assistance.

Frequently asked questions