Pontiac Fiero 1988 Service Manual page 469

6E2-A-14 DRIVEABILITY AMD EMISSIONS - FUEL INJECTION (TBI)
IGN
ECM
RED
PNK7BLK 439
- BLU 467 —
W16
W1
Aw
ECM
IGN
INJECTOR
DRIVER
-/
COIL
ASSEMBLIES
- BLK/WHT 450
SECONDARY
PNK — IGN
BLK/RED 453
PPL/WHT 430
TAN/BLK 424
— WHT 423
4-30-87
DIRECT IGNITION
SYSTEM MODULE
TO I.P.
OR TACH
WHT 121
B16
B9 B9
W 1 9
W 6
—I
GROUND
REFERENC
BY-PASS
EST
7S3586
6-26-86
CHART A-3
je 1 of
3)
IS B U T W O N T RUN
SERIES (TBI)
( P a g
ENGINE CRANK
2.5L "
Circuit Description:
Before using this chart, battery condition, engine cranking speed, and fuel quantity should be checked and
verified as being OK.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
4.
1. A "Service Engine Soon" light "ON" is a basic test
to determine if there is a 12 volt supply and
ignition 12 volts to ECM. No ALDL may be due to
an ECM problem, and CHART A-2 will diagnose
the ECM. If TPS is over 2.5 volts, the engine may
be in the clear flood mode, which will cause
starting problems. The engine will not start
without reference pulses and, therefore, the
"Scan" should read rpm (reference) during
cranking.
2. Because the Direct Ignition System uses two plugs
and wires to complete the circuit of each coil, the
opposite spark plug wire, should be left connected.
If rpm was indicated during crank, the ignition
module is receiving a crank signal, but "No
Spark" at this test indicates the ignition module is
not triggering the coil.
3. While cranking engine, there should be no fuel
spray with injector disconnected. Replace the
injector, if it sprays fuel or drips like a leaking
water faucet.
The test light should blink, indicating the ECM is
controlling the injectors OK. How bright the light
blinks is not important. However, the test light
should be a BT 8329 or equivalent.
5. Fuel Spray from the injector indicates that fuel is
available. However, the
engine
could be severly
flooded due to too much fuel. No fuel spray from
injector indicates a faulty fuel system or no ECM
control of injector.
Diagnostic Aids:
• The fuel pump test
terminal
is terminal "G" of the
ALDL connector.
• Water or foreign material can cause a no start
during freezing weather. The engine may start
after 5 or 6 minutes in a heated shop. The problem
may not re-occur until an overnight park in
freezing temperatures.
• An EGR sticking open can cause a low air/fuel
ratio during cranking. Unless engine enters
"Clear Flood" at the first indication of a flooding
condition, it can result in a no start.
• Fuel pressure: Low fuel pressure can result in a
very lean air/fuel ratio. See CHART A-7.