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Calculation Jaguar XK II facelift

Testing & Diagnostics 9 illustrations ~138 words

The "area ratio" method of analyzing the pump motor current is used in order to determine if a leak is present or not. The main advantage of this method is that the fault threshold is not dependent on the level in the fuel tank.

Two values are calculated, the relative pump current (Irel), which is given by

Scheme 28

Scheme 28: Calculation
Scheme 28: Calculation

And the Area Ratio (Ak), which is the area between the measured pump current and the ideal pump current (A1 in the chart below) divided by the area below the ideal pump current, corrected for the minimum pump current (A2 in the chart below)

Scheme 29

Scheme 29
Scheme 29

This graph shows the relationship between Area Ratio (Ak) and Relative Pump Current (Irel) for different leak conditions

Scheme 30

Scheme 30
Scheme 30

Scheme 31

Scheme 31: 4.3.3 Typical monitoring results
Scheme 31: 4.3.3 Typical monitoring results

Scheme 32

Scheme 32: 4.3.4 Monitoring Structure
Scheme 32: 4.3.4 Monitoring Structure

Scheme 33

Scheme 33
Scheme 33

Scheme 34

Scheme 34
Scheme 34

Scheme 35

Scheme 35: 4.3.5.1 No refueling detected; leak > 0.040"
Scheme 35: 4.3.5.1 No refueling detected; leak > 0.040"

Scheme 36

Scheme 36: 4.3.5.2 After refueling detected; leak > 0.020"
Scheme 36: 4.3.5.2 After refueling detected; leak > 0.020"