Pontiac Fiero 1988 Service Manual page 479

6E2-A-24 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (TBI)
CHART A-7
(Page 2 of 2)
FUEL SYSTEM DIAGNOSIS
2.5L "?" SERIES (TBI)
Test Description:
Numbers below refer to circled
numbers on the diagnostic chart.
1. Pressure but, less than 62 kPa (9 psi), falls into
two areas:
• Amount of fuel to injector OK, but pressure is
too low. System will be running lean and may
set Code 44. Also, hard starting cold and poor
overall performance.
• Restricted flow causing pressure drop -
Normally, a vehicle with a fuel pressure of less
than 62 kPa (9 psi) at idle will not be
driveable. However, if the pressure drop
occurs only while driving, the engine will
normally surge then stop as pressure begins to
drop rapidly to zero.
2. Restricting the fuel return line allows the fuel
pump to develop its maximum pressure (dead head
pressure). When battery voltage is applied to the
pump test terminal, pressure should be from 90 to
124 kPa (13 to 18 psi).
3. This test determines if the high fuel pressure is
due to a restricted fuel return line, or a throttle
body pressure regulator problem.