Coupe L4-1.9L DOHC VIN 7 (1994)
Fuel: Technical Service Bulletins
Fuel System - Fuel Effects on Driveability
BULLETIN NO.: 93-T-07A
ISSUE DATE: November, 1993
GROUP/SEQ. NO.: Engine - 02
CORPORATION NO.: 286304R
SUBJECT:
Fuel and How it Affects Driveability
Due to revisions in the affected model years, this bulletin supersedes bulletin 93-T-07, which should be discarded.
MODELS AFFECTED:
1991 - 1994 Saturn's
PURPOSE:
A number of inquires have been received from Retailers concerning fuel and how it affects driveability. This bulletin describes how gasoline and fuel
additives are constantly changing and gives details about diagnosing fuel-related driveability concerns.
DRIVEABILITY SYMPTOMS VERSUS FUEL QUALITY (ENGINE SYSTEMS FUNCTIONING PROPERLY)
Diagnostic Hints
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Start diagnosis by verifying the complaint. Keep the vehicle overnight before verifying a cold driveability problem.
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Remember that the symptom(s) may indicate a fuel delivery or fuel control problem. Use the Diagnostic Circuit Check and the fuel system diagnostic
procedures in the Service Manual for diagnosis.
^
If the engine is functioning properly, suspect fuel volatility.
Determine if the customer is using premium grade fuel. If so, suggest trying a different brand of fuel or regular fuel except when a higher grade is
recommended. Some premium grade gasoline may actually cause cold engine driveability problems because of their lower volatility in the warm-up
range. Inform the customers that it may require more than one tankful of a different brand of fuel to correct a fuel-quality problem.
Determine if the customer has old fuel in the tank. If so, the volatility may be too low because the "light-ends" have evaporated.
Consider the possibility that fuel volatility is incorrect for an UN-seasonable weather change.
