Start 9/9/2022.

• Don has a spare relay on hand
• Replacement pump costs $9000

Two DC electric boost pumps provide the engines with a standby fuel feed system. They are available for engine starting, and as a backup fuel feed source if either main ejector pump output pressure is too low to satisfactorily feed its respective engine. The left boost pump is powered by the DC battery bus, and the right boost pump by DC bus 2. The boost pumps are located downstream of their respective collector tanks, on the fuel feed lines to the engine-driven pumps. During normal operation, the only pilot action required is to arm both BOOST PUMP switches on the FUEL control panel prior to engine start, and disarm them after shutdown.

When both BOOST PUMP switches are armed, the boost pumps are activated if low pressure is sensed at either left or right main ejector pressure switch (this is the case prior to engine start).

If a single BOOST PUMP switch is armed, both boost pumps will be activated if low pressure is sensed on the armed side’s main ejector pressure switch. For example, if only the left BOOST PUMP switch is armed (pressed in), then both pumps will activate if low pressure is sensed at the left main ejector output. The boost pumps can provide fuel to both engines fuel feed systems through a crossover feed line.

If a boost pump has been activated, sufficient pump output pressure is indicated by the green ON legend in the switch/light. Insufficient output pressure is indicated by the amber INOP legend, and the L (R) FUEL PUMP caution EICAS message.

• Check pump grounds
• Failure to measure pressure could cause strange indication because one side pressure can cause other side's pump to operate

• A - L (R) P Switch = MAIN EJECTOR FAIL (Status MSG)
• B - L (R) P Switch = FUEL PUMP (Abnormal MSG)
• C - L (R) DeltaP Switch = SCAV EJECTOR (Abnormal MSG)
• D - L (R) T Switch = FUEL LO TEMP (Abnormal MSG)
• E - L (R) P Switch = FUEL FILTER (Abnormal MSG)
• F - (L) T Switch = BULK FUEL TEMP (Abnormal MSG)
• G - L (R) FUEL XFLOW SOV OPEN (Abnormal MSG)
• H - Engine-Driven Pump

Fuel Distribution Electrical Schematic

• Turn LH Switch On - Good

• Engage RH Switch On, LH Light IN-OP

• RH Switch In, LH Switch Out, RH Light On, LH Light On, then after 15 seconds IN-OP light On

• After 75 seconds, RW Switch In, LH Switch Out, RH Pump Light On, LH Pump Light On, Msg Removed

• LH IN-OP Light On, RH IN-OP Light On, Push LH Switch In, both IN-OP lights go Out, both pump lights go On - "Operation Normal"

• LH IN-OP Light On, RH IN-OP Light On, Push RH Switch In, (RH IN-OP light stays On) LH IN-OP light goes Out, after 1 second LH pump light On, RH Fuel Pump msg

• messages_0_9_.3gpp

• messages_0_10_.3gpp

• messages_0_11_.3gpp

• messages_0_12_.3gpp