Fuel Lines & Breather Hoses

MFI Pump Pre-Heat Hose - 25 x 440mm 

High-quality pre-heat hose with 25x440mm dimensions, designed for Porsche models equipped with Mechanical Fuel Injection (MFI) systems.

This hose connects the pre-heating circuit to the MFI pump, ensuring proper temperature regulation of the intake air and fuel system. Maintaining correct operating temperature is critical for smooth engine running, especially during cold starts and warm-up phases.

Fits:

• Porsche 911 1969-1973 2.2L / 2.4L / 2.7L RS LWB (F)
• Porsche 911 1974-1976 2.7L Carrera

Diagram ref no 39  

Manufactured to OEM specifications, this hose provides durability, flexibility, and resistance to engine bay heat, making it ideal for maintenance, repair, or restoration of classic Porsche MFI systems.

Key Features

• 25mm diameter, 440mm length pre-heat hose
• Suitable for Porsche MFI (Mechanical Fuel Injection) systems
• Part number 00004320521
• Designed for intake pre-heating circuits
• Supports proper engine warm-up operation
• Resistant to heat and engine bay conditions
• OEM-style fit and performance

Function and Purpose

This hose is an essential part of the MFI system.

It helps to:
• Deliver warm air to the MFI pump system
• Regulate intake and fuel system temperature
• Improve cold start performance
• Maintain stable engine running during warm-up
• Support efficient fuel injection operation

Why Replace Pre-Heat Hoses

Over time, pre-heat hoses degrade due to heat exposure.

Common issues include:
• Cracking or splitting
• Air leaks reducing system efficiency
• Hardening and reduced flexibility
• Poor cold start and warm-up performance

Replacing worn hoses ensures proper system operation and engine reliability.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

00004320521

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MFI Pump Pre-Heat Hose - 25 x 440mm 

High-quality pre-heat hose with 25x440mm dimensions, designed for Porsche models equipped with Mechanical Fuel Injection (MFI) systems.

This hose connects the pre-heating circuit to the MFI pump, ensuring proper temperature regulation of the intake air and fuel system. Maintaining correct operating temperature is critical for smooth engine running, especially during cold starts and warm-up phases.

Fits:

• Porsche 911 1969-1973 2.2L / 2.4L / 2.7L RS LWB (F)
• Porsche 911 1974-1976 2.7L Carrera

Diagram ref no 39  

Manufactured to OEM specifications, this hose provides durability, flexibility, and resistance to engine bay heat, making it ideal for maintenance, repair, or restoration of classic Porsche MFI systems.

Key Features

• 25mm diameter, 440mm length pre-heat hose
• Suitable for Porsche MFI (Mechanical Fuel Injection) systems
• Part number 00004320521
• Designed for intake pre-heating circuits
• Supports proper engine warm-up operation
• Resistant to heat and engine bay conditions
• OEM-style fit and performance

Function and Purpose

This hose is an essential part of the MFI system.

It helps to:
• Deliver warm air to the MFI pump system
• Regulate intake and fuel system temperature
• Improve cold start performance
• Maintain stable engine running during warm-up
• Support efficient fuel injection operation

Why Replace Pre-Heat Hoses

Over time, pre-heat hoses degrade due to heat exposure.

Common issues include:
• Cracking or splitting
• Air leaks reducing system efficiency
• Hardening and reduced flexibility
• Poor cold start and warm-up performance

Replacing worn hoses ensures proper system operation and engine reliability.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

00004320521

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Pressure Regulator to Diaphragm Damper Fuel



Fits:
Porsche 911 Carrera 1984-89

Click 'Zoom in' for large parts diagram.
Diagram ref no 19.

Related reference numbers
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93011041104

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Pressure regulator to diaphragm damper fuel.
A fuel supply hose that carries pressurised fuel from the fuel pressure regulator to the diaphragm damper (fuel accumulator / damper) in the L-Jetronic injection system of certain classic Porsche 911 models. The damper helps smooth fuel pressure pulses and supply consistent fuel pressure to the injectors.

Fits:
Porsche 911 Carrera 1984 - 1989

Diagram ref no 19

This fuel line delivers a consistent, pressurised flow of fuel from the regulator to the damper without leaks or pressure loss. Its modern fuel-resistant construction ensures durability against petrol, vapour, and ethanol-blended fuels while maintaining stable fuel pressure for reliable injector performance and preventing issues such as hesitation or lean running. By replacing old, hardened, or cracked hoses, it restores the safety and efficiency of the fuel system. Designed with the correct internal diameter and fittings, it provides proper fuel delivery, smooths pressure fluctuations, and offers long-term resistance to heat, vibration, and chemical exposure for dependable operation on 911 engines.

Over time, fuel hoses deteriorate: rubber hardens, cracks or swells; internal layers degrade; fittings loosen. On a fuel-line this can lead to:
• Fuel leaks - hazard to engine bay and fire risk
• Pressure loss or instability - causing poor fuel delivery, misfires or rough running
• Permeation or fuel vapour leakage - potentially causing poor cold start, smell, or regulatory issues
Replacing the old hose with a fresh line ensures safe, leak-free fuel flow, correct pressure regulation, and reliable injector performance - essential for performance, reliability, and safety on an air-cooled Porsche 911.

You should replace this fuel line if:
• The original hose is cracked, swollen, hardened, or leaking
• There are signs of fuel smell or seepage around the regulator / damper area
• You’re performing fuel system maintenance, pressure regulator overhaul or damper replacement
• You are upgrading to modern fuels (higher ethanol content or aggressive blends)
• You notice fuel delivery issues - hesitation, poor idle, uneven fuel pressure




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93011041104

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Protective sheath covering. 



Fits:

Porsche 911 / 912 - 1965 to 1989
Porsche 914

Protective sheathing cover for fuel ventilation lines and wiring harness

Click 'Zoom in' for large parts diagram.
Diagram ref no 42

Fuel Pressure Regulator to Return Line
The Genuine Porsche 93011050902 regulator to return fuel line is an OE fuel system hose for selected Porsche 911 Carrera 3.2L 1984–1989 models. It connects the fuel pressure regulator area to the return fuel circuit, helping maintain correct fuel routing and safe fuel system operation. Ideal for replacing an aged, cracked or leaking original fuel line during fuel system service, engine repair or classic 911 restoration.

Fits:
Porsche 911 Carrera 3.2L 1984 - 1989

Diagram ref no 11

This fuel line is used on selected Porsche 911 Carrera 3.2L fuel injection systems.

What This Part Does / Functions
•  Routes excess fuel from the fuel pressure regulator back to the return circuit
•  Helps maintain correct fuel system operation
•  Supports stable fuel pressure regulation
•  Connects into the fuel collection pipe / pressure regulator area
•  Helps prevent fuel leaks when the original hose is aged or damaged
•  Provides correct OE Porsche shape, routing and connection fitment
•  Replaces a cracked, hardened, leaking or deteriorated original fuel line
•  Supports reliable and safe operation of the fuel injection system.

Why Replace This Part?
Fuel hoses on classic Porsche 911 models are exposed to heat, fuel pressure, engine vibration and age-related deterioration. Over time, the hose can harden, crack, swell or leak. Because this line is located in the engine fuel system, any sign of fuel seepage should be treated seriously. Replacing it with a Genuine Porsche OE regulator to return fuel line helps restore the correct fuel routing and reduces the risk of fuel leaks in the engine bay.

Common Symptoms of a Faulty Fuel Return Line
•  Fuel smell from the engine bay
•  Visible fuel seepage around the hose or fittings
•  Cracked, hardened or swollen fuel hose
•  Dampness near the fuel pressure regulator area
•  Fuel staining around the return line connection
•  Poor fuel pressure stability if the line is restricted or damaged
•  Hose damage found during engine or intake service
•  Age-related deterioration on original fuel hoses.

When to Replace This Part
•  If the fuel line is cracked, brittle, swollen or leaking
•  If fuel smell is present around the engine bay
•  During fuel pressure regulator replacement
•  During fuel rail, fuel hose or intake manifold service
•  When replacing ageing engine bay fuel lines as preventative maintenance
•  If the vehicle still has original or unknown-age fuel hoses
•  During engine rebuild or recommissioning work
•  When restoring the fuel system with Genuine Porsche parts.

Where It Fits on the Car
This line fits in the engine bay fuel injection system. It connects the fuel pressure regulator area to the fuel return line circuit on the Porsche 911 3.2L engine. Correct routing and secure connections are essential because this is a fuel system component. Installation should be carried out carefully, with the system checked for leaks before the vehicle is driven.


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Fits:
Porsche 356B
Porsche 911 - 1965 to 1989
Porsche 964 - 1989 to 1994
Porsche 993 - 1994 to 1998
Porsche 944 - 1982 to 1989
Porsche 928 - 1978 to 1990

Click 'Zoom in' for large parts diagram.
Diagram ref no 15

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Fits:
Porsche 911 - 1965 to 1989
Porsche 964 - 1989 to 1994
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Porsche 914 - 1970 to 1976

Porsche 957 Cayenne - 2007 to 2010

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Fits:

Porsche 911 2.0ltr - 1965 to 1968

Diagram ref no 22

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Fits:

Porsche 911 2.0ltr - 1965 to 1968

Diagram ref no 7

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Fits:
Porsche 911 1965 to 1968

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Fits:
Porsche 911 - 1970 to 1989
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