Fuel Pump Power Consumption, Testing - BMW 5251 Service Manual

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Fuel Tank and Fuel
purnpl
Fuel pump power consumption, testing
To achieve accurate test results, the battery voltage at the
fuel pump connector should be 12.6 volts. Charge the battery
as necessary.
A higher than normal power consumption may indicate a
worn fuel pump, which may cause intermittent fuel starvation
due to pump overheating and seizure. The only remedy is
pump replacement. A lower than normal power consumption
may indicate a blockage. Be sure to check that the return line
and the pump pickup are not obstructed before replacing the
pump.
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Expose right side access cover:
Peel forward lip of carpet.
Release rubber grommet from center of access cover insu-
lation.
Peel back insulation at perforations to expose fuel tank ac-
cess cover.
Remove right side cover to expose electrical harness con-
nector.
Disconnect harness connector from tank sending unit by slid-
ing lock back. Lift off connector.
Test fuel pump for current draw by attaching digital ammeter
between pump and harness (terminal 2, whitelblue wire) and
connect a jumper wire between pump and harness (terminal
1, brown wire) as shown.
CAUTION-
Do not allow the test leads to short to ground.
NOTE-
See 600 Electrical Systern-General for information on elec-
trical tests using a digital multirneter.
Run pump as described in Operating fuel pump for tests.
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Compare ammeter reading with specification listed in ac-
companying table.
Fuel
pump
current
Current consumption (average) 9.5 amps