Home Repair and Service Manual Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine

Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine

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Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine

This repair gives step-by-step instructions on performing a low-pressure fuel test on the B46/B48 4-cylinder turbocharged engine. A low-pressure fuel test is necessary when trying to diagnose a faulty fuel pump or clogged fuel filter.
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Possible Symptoms: Not applicable for this repair.
This repair can be used on the following BMW models:
Intermediate level repair.

Step 1 - Purchase Parts

You will need the following parts and supplies to perform this repair.

Fuel Pressure Test Gauge - Quick Disconnect

Checking the fuel pressure in your BMW or MINI is a necessity for diagnosing faulty fuel pumps and clogged fuel filters. This easy-to-use kit quickly snaps onto you quick disconnect giving you accurate fuel pressure readings up to 7 bar (100 psi).

Step 2 - Repair Procedure

Unless otherwise noted, all vehicle repair step images in this article are copyrighted, and used courtesy of BMW of North America, Inc. .
Warning
Fuel spillage!

  • A small amount of fuel will be discharged during this procedure. Have rags ready

Technical Information

You must have a fuel pressure test kit to perform this repair. Please see our special tools block above to order one.

1. Test fuel pressure.
Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine
Click to enlarge image

- Locate the black plastic cover (1) on the left rear of engine next to the strut tower.

Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine
Click to enlarge image

- The fuel line quick disconnect (1) is located under the cover. Use a small pick to remove the gray plastic safety clip.

View part diagram for this step
Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine
Click to enlarge image

- Push the release collar (1) in (direction of arrow).

- Pull the quick disconnect apart releasing the fuel hose from the fuel line. Have rags ready to catch any fuel that escapes.

View part diagram for this step
Fuel Pressure Test – BMW B46/B48 Turbo 4-cylinder Engine
Click to enlarge image

- Attach (A) of fuel test adapter to fuel hose, (B) to fuel line, and (C) to pressure guage.

- Start vehicle (if possible) and read pressure. If vehicle won't run, read pressure level while a helper attempts to start the vehicle.

Notes on fuel pressure for the B46/B48 engine
Notes on fuel pressure for the B46/B48 engine:

This procedure measures the low pressure side of the system that feeds the high pressure fuel pump.

A low pressure (or no pressure reading) may signify a faulty low pressure fuel pump or clogged fuel filter.

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