Pontiac Fiero 1988 Service Manual page 595

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CHART A-3
(Page 1 of 2)
ENGINE CRANKS BUT WON'T RUN
2.8L "P" SERIES (PORT)
C i r c u i t D e s c r i p t i o n :
This chart assumes that battery condition and engine cranking speed are OK, and there Is adequate fuel in
the tank.
T e s t D e s c r i p t i o n :
Numbers below refer to circled
numbers on the diagnostic chart.
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 crank.
2. No spark may be caused by one of several
components related to the ignition system.
CHART C-4 will address all problems related to
the causes of a no spark condition.
3. 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 J-34730-3 or equivalent.
4. Use fuel pressure gage J-34730-1 or equivalent.
Wrap a shop towel around the fuel pressure tap to
absorb any small amount of fuel leakage that may
occur when installing the gage.
D i a g n o s t i c A i d s : .
• An EGR valve 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.
• Check for fouled plugs.
• A defective cold start circuit or water in fuel line
can cause a no start in cold weather. See CHART
A-9.
• Also check that injectors on both sides of engine
will cause a test light to "blink". If not OK, check
injector fuses.
Checking of two injectors on each bank will locate
a shorted injector.
• Also check that injectors are not opened or
shorted. Injector resistance should be greater
than 10 ohms.
If above are all OK, refer to "Symptoms'
Section "B," "Hard Start".
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