Diagnostic Aids

If the engine cranks but does not run condition occurs only in cold ambient temperatures, fuel contamination, poor fuel quality or fuel waxing may be the cause. Fuel icing, due to water contamination and fuel waxing may cause fuel system restrictions significant enough to prevent the engine from starting. A restriction will be indicated by a high vacuum in the fuel supply lines while cranking the engine in a cold state. The engine may start after the vehicle is brought into the service bay and the fuel is sufficiently warmed up. The use of an unapproved fuel, such as fuel containing greater than 5 % biodiesel, may cause severe fuel system restrictions. Unapproved fuel usage can also cause the engine to start and stall or to start but have no acceleration. Engine block heaters may be used to alleviate some fuel icing and waxing concerns.