Pontiac Fiero 1988 Service Manual page 603

6E3-A-20 D R I V A B 1 L I T Y A N D E M I S S I O N S - F U E L I N J E C T I O N ( P O R T )
ECM
RELAY
HARNESS
CONNECTOR
I. P.
CONNECTOR
OIL PRESS.
f / /
SWITCH ' A
ORN/BLK
FUELPUMP«
RELAY
440
TO
- • B A T T E R Y
FUEL PUMP 1 2 v
N.O.
f
D A
o
B A
o o
G
o
TAN/WHT
DK GRN/WHT 465
BLK/WHT 450
A1
D1
12 VOLT
RELAY DRIVE
ENGINE
GROUND
FUEL PUMP
(IN TANK)
ALDL CONNECTOR
7-8-87
15 W A Y I.P.
CONNECTOR
NAY
_L
3WAY
CONNECTOR
6-17-87
* 5 S 1 9 0 2 - 6 E
CHART A-7
(Page 3 of 4)
FUEL SYSTEM DIAGNOSIS
2.8L "P" SERIES (PORT)
Test Description:
Numbers below refer to circled
numbers on the diagnostic chart.
6. Checks for ECM control of relay through CKT 465.
7. The fuel pump voltage control circuit includes an
engine oil pressure switch with a separate set of
normally open contacts. The switch closes at about
(4 lbs) 27 kPa of oil pressure and provides a second
battery feed path to the fuel pump. If the relay
fails, the pump will continue to run using the
battery feed supplied by the closed oil pressure
switch.
A failed pump relay may result in extended engine
crank time, because of the time required to build
enough oil pressure to close the oil pressure switch
and turn "ON" the fuel pump.
There may be instances when the relay has failed
but the engine will not crank fast enough to build
enough oil pressure to close the switch. This or a
faulty oil pressure switch can result in "Engine
Cranks But Will Not Run".
8. Checks the oil pressure switch to be sure it
provides battery feed to the fuel pump should the
pump relay fail.
9. Checks for open oil pressure switch with ignition
"OFF". Should the switch stick closed, the fuel
pump will continue to run and discharge the
battery.
Diagnostic Aids:
Fuel pump relay driver is fault protected. Before
replacing ECM, replace relay and retest with original
ECM.