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 chart of the thermal timer.
If the measured pressure is below normal, the control pressure regulator is defective.
If the measured pressure is higher than normal, this indicates insufficient fuel drain or a malfunction of the pilot pressure regulator.
Check for foreign matter in drain line, replace pilot pressure regulator and check pilot pressure again with cold engine.
Checking the pilot pressure on a hot engine
Warm up the engine.
Turn on the fuel pump directly as above.
Connect the pressure gauge as above and open the two-way valve.
Measure the control pressure, which should be between 2.7-3.1 kg/cm2.
Start the engine and measure the control pressure at idle, which should be between 3.4-3.8 kg / cm2.
If abnormal, check the condition of the vacuum hose connecting the control pressure regulator to the intake manifold.
If the vacuum hose is OK, replace the control pressure regulator and check the control pressure again with a hot engine.
Fuel pressure test
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 above. Measure the fuel supply pressure, which should be between 4.5-5.2 kg / cm2.
Causes of insufficient fuel supply pressure can be:
- leakage of fuel lines and their connections;
- severe contamination of the fuel fine filter;
- self-ignition of a combustible mixture;
- insufficient performance of the fuel pump;
- violation of the fuel pressure regulation.
The causes of increased fuel supply pressure are:
- insufficient fuel drain;
- 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 shims installed on the plunger of the fuel pressure regulator in the system.