Engine - Hard Start/Stalling/Poor Economy

89ford14

Article No. 9-12-9

^ FUEL ECONOMY - POOR - 5.8L-4V HIGH ALTITUDE

CALIBRATIONS-SERVICE TIPS

^ HARD START - 5.8L - 4V HIGH ALTITUDE CALIBRATIONS - SERVICE TIPS

^ STALL - 5.8L-4V HIGH ALTITUDE CALIBRATIONSSERVICE TIPS

LIGHT TRUCK: 1984-87 ECONOLINE, F SUPER DUTY, F-150, F-250, F-350

MEDIUM/HEAVY TRUCK: 1984-87 F & B SERIES

ISSUE: A rich running engine at high altitude may be caused by incorrect vacuum hose and electrical connections. The overly rich condition can cause stalling, hard starting, or poor fuel economy.

ACTION: Listed below are some incorrect vacuum and electrical connections that have been found in the field. Technicians should check for these conditions before trying further diagnosis.

^ Spark port or EGR port vacuum supplied to 5" and 10" Hg. vacuum switch instead of manifold vacuum.

^ Manifold vacuum signal applied to off-idle vacuum switch instead of EGR port vacuum signal

^ Wrong vacuum hose routing for the altitude compensator system (check vacuum schematic).

^ Wrong electrical connections - like connecting a wire to a 7V source when it should be connected to a 12V power source.

^ Vacuum filter is restricted or plugged by a cap or other object.

OTHER APPLICABLE ARTICLES: 86-12-17
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 610000, 620100, 640200