How To Check Fuel Pressure

how to check fuel pressure

Sometimes,we have to measure the fuel pressure of the engine fuel supply system when repairing a car breakdown.

How to detect the fuel pressure of the engine fuel supply system?

I believe that many people still won’t.so let’s take a look at the engine fuel pressure check method.

Tips:To accurately test fuel data,you still need to use a fuel pressure tester to help us get the job done!


Fuel pressure inspection method:

1.How To Check Fuel Pressure Without Gauge

When the electric fuel pump is working,hold the oil hose by hand and judge.whether the fuel pressure is too low by the magnitude of its tension.The experience check is simple.but the accuracy is slightly worse.

How To Check Fuel Pressure Without Gauge

2.How To Check A Fuel Pressure Regulator

Steps to check fuel pressure with oil pressure gauge:

1.Pressure relief:

First unplug the fuel pump fuse,relay or oil pump plug.Then start the engine until the engine turns off automatically.

Which start the engine again 2 or 3 times.then remove the battery negative.

2.Install the fuel pressure gauge:

The fuel pressure gauge is connected in series in the oil inlet pipe.

The vehicle with the pressure measuring port connects the fuel pressure gauge to the pressure measuring port.

When removing the oil pipe,a towel or cotton cloth is used under the oil pipe connection to prevent the fuel from leaking to the ground.

3.Check oil pressure:

Static oil pressure,idle oil pressure,maximum oil pressure,residual oil pressure

Static oil pressure:

Do not start the engine,connect the two terminals on the oil pump diagnostic connector (the “+B” and “FB” terminals of the Toyota car) with the jumper.

turn the ignition switch to the “ON” position to make the oil pump work,static oil pressure Generally around 300 KPa.

Idle oil pressure:

Install the fuel pump fuse or relay to start the engine and make the fuel pump run at idle speed.

At this time,the oil pressure gauge reads the idle working oil pressure.

The normal value of the Toyota car system should be 200-300KPa.

Maximum oil pressure:

Hold the return pipe with pliers covered with a soft cloth.

At this time,the oil pressure gauge reads the maximum oil supply pressure of the oil pump.

which is generally 2 to 3 times the normal working oil pressure.

Residual oil pressure:

When the oil pipe clamp is released,the engine is turned off.

after the fuel pump is stopped for 10 minutes,the pressure of the oil pipe should be greater than 150 KPa.

Note unit conversion: 1Mpa=1000Kpa; 1bar=1kgcm2=14.2psi=100Kpa

4. Oil pressure analysis:

Oil pressure gauge reading four cases – Zero oil pressure, normal oil pressure, high oil pressure and low oil pressure.

If the oil pressure is zero, first check the oil storage capacity of the fuel tank.

whether the oil passage is seriously leaked and the fuel filter is completely blocked.

After eliminating the possibility,the oil pressure is still zero.

Then check the control circuit of the fuel system.

For example:the fuse is blown ,the relay is not working,the oil pump circuit harness is open and the oil pump is damaged.

If the oil pressure is too high, mainly check whether the vacuum tube at the top of the pressure regulator is loose or ruptured.

whether the oil pressure regulator return pipe is blocked or not.

When the fuel pressure is too low or the oil pump stops working for 2-5 minutes, the oil pressure drops rapidly.

Under the premise of eliminating the leakage of the oil passage.

there are leakage phenomena in the injector,fuel pressure regulator failure,fuel filter clogging and oil pump failure.

5.Disassemble the fuel pressure gauge:

First relieve the pressure,then remove the fuel pressure gauge.Reconnect the oil inlet pipe.start the engine and check the oil pipe leaks.

How To Check A Fuel Pressure Regulator


Checking precautions for engine fuel pressure:

1.Pay attention to ventilation, prevent fire sources and prepare fire-fighting facilities

2.Always remove the pressure before disassembling the fuel pipe

3.The oil pipe shall not have aging leakage

4.Seals and buckles are disposable parts and  replaced during maintenance

5.Be careful when starting the engine

Leave a Reply

Your email address will not be published. Required fields are marked *