fuel pressure BMW 735i 2000 E38 M62TU Engine Workshop Manual

PHASE 2 - LEAK DETECTION

The ECM energizes the Change Over Valve allowing the pressurized air to enter the fuel sys-

tem through the Charcoal Canister, The ECM monitors the current flow and compares it

with the stored reference measurement over a duration of time.

Once the test is concluded, the ECM stops the pump motor and immediately de-energizes

the change over valve. This allows the stored pressure to vent thorough the charcoal can-

ister trapping hydrocarbon vapor and venting air to atmosphere through the filter.
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TEST RESULTS

The time duration varies between 45 & 270 seconds depending on the resulting leak diag-

nosis test results (developed tank pressure “amperage” / within a specific time period).

However the chart below depicts the logic used to determine fuel system leaks.
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