L PRI PUMP OFF
(Status)

L PRI PUMPS OFF (Status) shows when the conditions that follow occur:

• The L WING FEED INHIBIT PRI PUMPS switch on the FUEL control panel is set to OFF.
• The left aft boost-pump pressure is low.
• The left forward boost-pump pressure is low.

This troubleshooting applies when it is not under normal conditions.

• L WING FEED INHIBIT PRI PUMPS Switch (SDS2)
• Fuel Control Panel (AP5)
• Fuel Management and Quantity Gauging Computer (FMQGC) (A47)
• Ground Stud (GS852)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

The L PRI PUMPS OFF (Status) CAS does not display when the L PRI PUMPS switch is turned OFF.

1. Turn ON aircraft power and the CAIMS PMAT.

   • Access CAIMS.
   • Select System Diagnostics.
   • Select 28-00 Fuel.
   • Select Computer (FMQGC CH A(B))
   • Select LRU Test.
   • Select Cockpit fuel panel data - CH A(B).

2. Scroll through the pages and find Left Primary Pumps Panel Switch:
3. On the Fuel control panel (AP5) select the L PRI PUMP switch.
4. Does the pump status change from INHIB to ON and ON to INHIB on the CAIMS page?

   1. If the status changes, then go to step 10.
   2. If the status does not change, continue with the next step.

5. Gain access to the FMQGC (A47) and remove FMQGC from the tray.
6. Perform the wiring continuity test per the table below:
   

   SWITCH POSITION	FROM	TO	EXPECTED RESULT	RESULT
   L PRI PUMPS (OFF)	A47AP1 - G12	Airframe Ground	Continuity

   1. If the wiring check is good, go to step 10.
   2. If the wiring check is not good, then continue with next step.

7. Remove the fuel control panel (AP5), disconnect AP5P1.
8. Perform the wiring continuity test per the table below:
   

   FROM	TO	EXPECTED RESULT	RESULT
   AP5J1 - 47	AP5J1 - 15	Continuity
   AP5P1 - 15	Airframe Ground	Continuity

   1. If the wiring from AP5J1 - 47 to AP5J1 - 15 is not good, suspect the L PRIMARY FUEL PUMP Switch (SDS2), or the Fuel Control Panel.
   2. If the wiring from AP5P1 - 15 to airframe ground is not good then repair or replace wiring to GS852, or GS852.
   3. If the wiring check is good then continue with the next step.

9. Perform the wiring continuity test per the table below:
   

   FROM	TO	EXPECTED RESULT	RESULT
   AP5P1 - 47	A47AP1 - G12	Continuity

   1. If the wiring check is good go to next step.
   2. If the wiring check is not good then repair or replace wiring between Fuel Control Panel and FMQGC.

10. Re-install or Re-rack the FMQGC making sure it is fully and properly pushed into place. Is the fault still present?

    1. If the CAS does not display, go to next step.
    2. If the CAS displays, then do close out.

11. Suspect the FMQGC (A47).
12. Do close out.