FUEL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
FUEL SYSTEM PRESSURE TEST - CONTINUED
Checking Fuel Transfer Pump Output Pressure - Continued
N OT E
If contamination is not found and pressure regulating valve is worn out, replace fuel transfer pump
(WP 0188 00).
Once the fuel transfer pump is operating properly, check fuel pressure again at secondary fuel filter
base. Refer to Checking Fuel Pressure After Secondary Filter in this work package.
If dirt is found, clean valve assembly and reinstall valve assembly.
Reinstall access plug.
Check fuel pressure again.
Replace fuel transfer pump (WP 0188 00) if fuel pressure still measures less than 95 psi (655 kPa).
N OT E
Return fuel pressure regulating valve is located on the bottom of fuel filter base.
Inspecting Fuel Pressure regulating Valve
Inspect return fuel pressure regulating valve for wear.
Check fuel pressure again at secondary fuel filter base. Refer to Checking Fuel Pressure After Secondary Filter in this
work package. If fuel pressure is not up to 85 psi (586 kPa), perform Measuring Vacuum at Primary Filter in this work
If primary filter and fuel lines are sized correctly, replace secondary fuel filter base (WP 0036 00).
Measuring Vacuum at Primary Filter
Adjust engine speed to 1,800 rpm with no load.
Measure vacuum at outlet of primary filter.
Vacuum should be 3 to 4 inHg (10.14 to 13.52 kPa).
If vacuum is more than 9 inHg (30.42 kPa), measure vacuum at inlet of primary filter.
Differential across primary filter should be less than 1 inHg (3.38 kPa) with a new filter installed.
If differential is higher by more than 1 inHg (3.38 kPa), ensure filter, fittings, and lines are correctly sized. Fuel lines
should be 0.5 in. (12.7 mm). Also check for debris in fuel tank that may be plugging supply tube.