B14-24: Checking All Pressures
Checking all pressuresOperations B14-24
B14
Fig. 4 Fuel pressure gauge connections.:
Connect pressure gauge 5011
Turn off the ignition.
Connect the gauge between the control pressure regulator and fuel distributor.
E/F: use pressure gauge 5011, hose 5116 and adapter 5032.
Turbo: use pressure gauge 5011 and adapters 5228 and 5229.
B15
Turn on the ignition to start the fuel pump
B16
Check the line pressure
Turn the gauge cock on 5011 to position 1 (towards the fuel distributor).
Record the pressure when stable.
The line pressure must be:
E/F 450-530 kPa (65-77 psi)
Turbo 520-580 kPa (75-84 psi)
Too low: Proceed to B54 B54-58: From B16: Line pressure too low
Too high: Proceed to B59 B59-60: From B16: Line Pressure Too High
B17
Check the control pressure (cold control pressure regulator)
Turn the gauge cock on 5011 to position 2 (at right angles to the hoses).
The control pressure regulator should be at the temperature of the surroundings.
The correct control pressures at different surrounding temperatures are shown on the graphs.
Control Pressure Regulator ...004 And ...082:
Control Pressure Regulator ...014:
Control Pressure Regulator ...021:
Control Pressure Regulator ...079:
Too low: test with a new control pressure regulator.
Too high: Proceed to B61 B61: From B17 and B18: Control Pressure Too High
B18
Check the control pressure (warm control pressure regulator)
Connect the plug to the control pressure regulator. The regulator now receives current and will heat up.
After max. 5 minutes the control pressure should have increased to 345-375 kPa (50-54 psi).
Too low: Proceed to B62 B62-63: From B18: Control Pressure Too Low
Too high: Proceed to B61 B61: From B17 and B18: Control Pressure Too High
Full load enrichment E-Turbo engines only
Operations B19-20
B19
Check enrichment at full load
Block the hose between the control pressure regulator and the nipple on the intake manifold. Use clamping pliers 2901.
Disconnect the hose from the nipple on the throttle housing. Connect the pressure gauge 5230 and a pump.
Increase the pressure by pumping to 45 kPa (6.5 psi).
The control pressure should now drop to 265-295 kPa (38-43 psi).
Remove pliers 2901, pressure gauge 5230 and the pump.
Reconnect the hose to the throttle housing.
Incorrect control pressure: test with a new control pressure regulator.
B20
Check the pressure sensor
Connect the pressure gauge 5230 and pump to the hose leading to the pressure sensor. (The pressure sensor is located on the inside of the firewall (bulkhead) above the pedal carrier.)
Increase the pressure until the fuel pump stops working. This can be checked by placing the hand on the fuel filter (the pressure sensor interrupts the pump relay earth/ground connection).
Caution! Do not exceed 120 kPa (17 psi). Otherwise the boost pressure gauge on the dashboard may be damaged.
The fuel pump should stop at a pressure of 90 kPa (13 psi). At the same time, the boost pressure gauge should indicate red and the turbo lamp should glow.
Disconnect the pressure gauge 5230 and the pump. Reconnect the hose to the intake manifold.
If Incorrect: test with a new pressure sensor.
Acceleration enrichment F-engines USA (incl. Turbo) 1981- models only
B21
Check the enrichment during acceleration
The engine must be cold (below +50°C = 118°F).
Connect the plug to the ignition system control unit.
Start the engine.
Rev up the engine quickly and record the control pressure on pressure gauge 5011. The pressure should drop for a short time (1 sec.) and then return to the original value.
Leave the engine idling until the temperature reaches +55°C (130°F). Rev up the engine and check that the control pressure does not drop (the thermostat valve disconnects the system at approx. +53°C = 127°F).
Turn off the engine.
Disconnect the plug from the ignition system control unit.
B22
Check the rest pressure
Turn the gauge cock on 5011 to position 2 (at right angles to the hoses).
Turn off the ignition.
Record the pressure for 1 minute after it has stabilized.
The rest pressure should be:
E/F and Turbo 1981: 150-240 kPa (22-35 psi)
Turbo 1982-: 240-320 kPa (35-46 psi)
Pressure does not drop but is incorrect: adjust the line and rest pressures. Proceed to B70.
Pressure drops: Proceed to B64 B64-67: From B22-23: Rest Pressure Drops
B23
Check the pressure drop for 20 minutes
Especially important if a warm engine is difficult to start
After 20 minutes. the pressure should be:
E/F and Turbo 1981: min. 150 kPa (22 psi)
Turbo 1982-: min 240 kPa (35 psi)
Too low: Proceed to B64 B64-67: From B22-23: Rest Pressure Drops
B24
Disconnect the pressure gauge 5011 and adapters (hose)
Reconnect the hose between the fuel distributor and control pressure regulator.