Fuel - Volatility Related Driveability Concerns

Article No.
98-26-2

01/04/99

FUEL - INFORMATION ON GASOLINE - TIPS TO
RESOLVE VOLATILITY RELATED DRIVEABILITY
CONCERNS

FORD:
1985-97 THUNDERBIRD
1986-99 MUSTANG, TAURUS
1987-99 ESCORT
1988-94 TEMPO
1989-97 PROBE
1990-99 CROWN VICTORIA
1992-93 FESTIVA
1995-99 CONTOUR

LINCOLN-MERCURY:
1985-97 COUGAR
1986-92 MARK VII
1986-99 SABLE
1987-89 TRACER
1988-94 TOPAZ
1988-99 CONTINENTAL
1990-99 GRAND MARQUIS, TOWN CAR
1991-99 TRACER
1993-98 MARK VIII
1995-99 MYSTIQUE
1999 COUGAR

LIGHT TRUCK:
1986-97 AEROSTAR
1987-96 BRONCO
1989-97 F SUPER DUTY, F-350
1989-99 F-150, F-250 LD, RANGER
1991-99 EXPLORER
1992-99 ECONOLINE
1993-99 VILLAGER
1995-99 WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 SUPER DUTY F SERIES

MEDIUM/HEAVY TRUCK:
1990-97 F-700

This TSB article is being republished in its entirety to expand vehicle model coverage and revise the text.

ISSUE
Some vehicles using winter blend fuels may exhibit a stall on start up and a no restart, hard start condition or a no start condition in unseasonably hot weather (greater than 27°C/80°F). These concerns may be related to fuel volatility from winter blend fuels during winter-spring and autumn-winter transitions and may result in a fuel pump vapor lock condition. This condition may appear to be a fuel pump failure but may be caused by winter blend fuel.

ACTION
Refer to the following text for further information.

NOTE
FUEL TANK ADDITIVES WILL NOT RESOLVE THESE CONCERNS BECAUSE VAPOR FORMS FROM CAVITATION WITHIN THE FUEL PUMP.

FILLING THE TANK TO FULL MAY BE EFFECTIVE. ADVISE CUSTOMER TO USE THE RECOMMENDED OCTANE GRADE PER OWNER MANUAL AND NOT A HIGHER GRADE.

Explain to the customer that this concern may be due to a low tank level of winter blend fuel combined with unseasonably warm weather. Advise customer that filling the fuel tank to full may be effective in resolving this concern. Also, advise customer to use the recommended octane grade per their Owner Manual and not a higher grade.

BACKGROUND
Gasolines are seasonally adjusted, meaning they have higher volatility (vaporize easier) in the winter and lower volatility in the summer. Government mandates to improve air quality have resulted in significant changes to gasolines, such as the mandatory use of oxygenates (ethanol, methyl tertiary butyl ether (MTBE), and others) in the winter or the reduction of Reid Vapor Pressure (RVP) in the summer. The addition of oxygenates (especially ethanol) increases volatility while the reduction of RVP reduces volatility.

Gasoline distribution practices often do not allow branded marketers to have much control over their gasoline's volatility other than RVP. Oxygenate (e.g., ethanol, MTBE) use is more dependent on local gasoline markets, rather than specific marketers practice. Therefore, it is difficult to recommend specific brands to avoid volatility related complaints.

OTHER APPLICABLE ARTICLES: 91-8-13

SUPERSEDES: 96-5-4

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 402000, 404000, 602300, 603300,
607000, 607400, 608000, 608400,
609000, 609400, 610000, 611000,
611500, 612000, 614000, 614500,
623000