Pressure check (BMW 3 Series E21)

Connect one hose of pressure gauge 13 3 060 with fittings 13 3 065 and 13 3 066 and with a two-way valve to the control pressure fitting of the fuel dispenser-distributor, and the other to the control pressure pipeline. Open the two-way valve.

Checking the control pressure on a cold engine

Turn on the fuel pump directly as above and measure the control pressure.

Compare the measurement result with the values indicated on the operating graph of the thermal time relay.

If the measured pressure is below normal, the control pressure regulator is faulty.

If the measured pressure is higher than normal, this indicates insufficient fuel drainage or a faulty control pressure regulator.

Check for foreign matter in the drain line, replace the pilot pressure regulator and recheck the pilot pressure with the engine cold.

Checking the control pressure on a hot engine

Warm up the engine.

Turn on the fuel pump directly as described above.

Connect the pressure gauge as described above and open the two-way valve.

Measure the control pressure, which should be within 2.7-3.1 kg/cm².

Start the engine and measure the idle control pressure, which should be within 3.4-3.8 kg/cm².



If there is any deviation from the norm, check the condition of the vacuum hose connecting the control pressure regulator to the intake manifold.

If the vacuum hose is good, replace the pilot pressure regulator and recheck the pilot pressure with the engine hot.

Checking the fuel supply pressure

Check the condition of the fuel pump and fine fuel filter.

Connect the pressure gauge as above and close the two-way valve.

Turn on the fuel pump directly as described above. Measure the fuel supply pressure, which should be within 4.5-5.2 kg/cm².

Reasons for insufficient fuel supply pressure may be:

• leaks in fuel lines and their connections;
• severe contamination of the fine fuel filter;
• spontaneous combustion of a combustible mixture;
• insufficient fuel pump performance;
• violation of fuel supply pressure regulation.

The reasons for increased fuel supply pressure are:

• insufficient fuel drainage;
• violation of the adjustment of the fuel pressure regulator in the system or jamming of its plunger.

The fuel supply pressure is regulated by selecting the thickness of the adjusting washers installed on the plunger of the fuel pressure regulator in the system.





(The original version is on the portal «BMWman»)