Checking the fuel pressure of a Renault Sandero car

This article will look at how to check the fuel pressure and relieve the fuel pressure of this car

During diagnostic work on the engine, it is often necessary to measure the fuel pressure in the fuel line.

It is necessary to relieve fuel pressure when carrying out work on repairing the power system, when it is necessary to disconnect any hoses or fuel lines.

Fuel pressure relief

To reduce fuel pressure, open the hood and disconnect the negative battery terminal

Open the mounting block in the engine compartment on the left side

We remove the fuel pump relay from the mounting block (shown by the arrow)

After that, connect the negative terminal to the battery and start the engine.

Let the engine run until the rail and injectors run out of fuel. After that, the engine will stall.

Turn off the ignition.

Now you can work on the fuel system.

Checking fuel pressure

An indicator of the health of the engine power system is the fuel pressure in the fuel rail.

In case of insufficient fuel pressure, the following are possible:

• – unstable engine operation;
• – stop the engine at idle;
• - reduced idle speed of the crankshaft;
• - insufficient throttle response of the car (the engine does not develop full power);
• - dips in the engine when the car is moving.

First, you need to check the reliability of the electrical contacts in the blocks of the ECM wiring harnesses responsible for the fuel supply (fuel pump module, injectors, fuel relay and appropriate fuses).

Turn on the ignition and listen: within a few seconds you should hear the sound of the electric fuel pump.

If you can't hear it, check the power supply circuit of the electric fuel pump.

If you turned on the ignition three times without trying to start the engine, the electric fuel pump will not turn on again, which is not a sign of a malfunction.

It will turn on at the same time as the starter starts the engine.

Depressurize the supply system as described above

Disconnect the pressure pipe from the fuel pump

To check the fuel pressure, we connect a pressure gauge (with a measurement limit of at least 5 kgf / cm ²) between the fuel pump and the pressure pipe

We install the relay in the mounting block, which was removed when the pressure in the power system was reduced

Starting the engine.

When the engine is running at idle, the pressure in the fuel line must be at least 3 kgf / cm ².

The following reasons for pressure drop are possible:

• - malfunction of the fuel pressure regulator;
• - fuel pump malfunction;
• - contamination of the fuel fine filter;
• - clogged strainer in the fuel pump module.

Stop the engine and release the fuel pressure. Disconnect the pressure gauge from the power system.