Pontiac Fiero 1988 Service Manual page 642

DRIVEABILITY AND EMISSIONS - FUEL INJECTION (PORT) 6E3-B-3
HARD START
Definition; Engine cranks OK, but does not start for a long time. Does
eventually run, or may start but immediately dies.
• Perform careful check as described at start of
Section "B".
• - Make sure driver is using correct starting
procedure.
• CHECK:
TPS for sticking or binding or a high
throttle position sensor (TPS) voltage with
the throttle closed.
High resistance in coolant sensor circuit or
sensor itself. See CODE 15 CHART OR
with a "Scan" tool compare coolant
temperature with ambient temperature on
a cold engine.
- Fuel pressure CHART A-7.
Water contaminated fuel.
Exhaust gas recirculation (EGR) operation.
Be sure valve seats properly and is not
staying open. See CHART C-7.
- Fuel pump relay - See CHART A-7.
Ignition system - Check distributor for:
Proper Output with ST-125.
Worn shaft.
Bare and shorted wires.
Pickup coil resistance and connections.
Loose ignition coil ground.
Moisture in distributor cap.
• If problem exists in cold weather, check cold
start valve. See CHART A-9 .
® A faulty in-tank fuel pump check valve will
allow the fuel in the lines to drain back to the
tank after the engine is stopped. To check for
this condition:
Perform Fuel System Diagnosis,
CHART A-7.
• Remove spark plugs. Check for wet plugs,
cracks, wear, improper gap, burned electrodes,
or heavy deposits. Repair or replace as
necessary.
• If engine starts but then immediately stalls
open distributor by-pass line. If engine then
starts and runs OK, replace pickup coil.
HESITATION, SAG, STUMBLE
Definition: Momentary lack of response as the accelerator is pushed down. Can
occur at all car speeds. Usually most severe when first trying to make the car move, as
from a stop sign. May cause the engine to stall if severe enough.
• Perform careful visual check as described at
start of Section "B".
• CHECK:
- Fuel pressure. See CHART A-7. Also
Check for water contaminated fuel.
Spark plugs for being fouled or faulty
wiring.
Programmable read only memory (PROM)
number. Also check Service Bulletins for
latest PROM.
TPS for binding or sticking. Voltage
should increase at a steady rate as throttle
is moved toward wide open throttle (WOT).
Manifold absolute pressure (MAP) Sensor -
CHART C-1D.
Ignition timing. See Emission Control
Information label.
Generator output voltage. Repair if less
than 9 or more than 16 volts.
High energy ignition (HEI) ground, CKT
453.
Canister purge system for proper operation.
See CHART C-3.
- EGR-See CHART C-7.
Engine Thermostat - functioning correctly
and proper heat range.
• Perform injector balance test CHART C-2A.