1992 Jaguar XJS V12 Two Wheel Drive Automatic 80,000 miles
My jag has a moderately loud steady humming coming from behind the back seat --- the fuel pump of course. It is loud enough that you can hear it over the radio turned up to normal listening levels. This in itself seems abnormal to hear the continuous humming of the pump.
Secondly, after the car is driven for about 30 to 40 miles or more you can start smelling the fuel. The car runs great without hesitation, etc. The fuel pump must be working but not sure to what degree. When removing the gas filler cap after the above sequence, there is a TREMENDOUS release of pressure from the gas tank; literally enough force to mist out some gas in a large GUSH. When reapplying the gas cap and only one minute later taking off again, there is still a large amt of pressure release from the tank -- like the tank isn't ventilating or something.
Is my issue a fuel pump problem, tank ventilation problem or something else.
FUEL EVAPORATIVE SYSTEM
The fuel evaporative system is designed to keep fuel and crankcase vapor from escaping into the atmosphere. See Fig. 2 or Fig. 4. The fuel tank is vented through a system of vapor pipes and liquid/vapor separator, to a charcoal (vapor) canister in the engine compartment.
The flow of vapors into the canister is controlled by a tank pressure/vacuum relief valve. Vapors absorbed in the canister are purged by engine vacuum through the electrical purge control valve. Electrical purge control valve is controlled by the PCM. The rate of purge is dependent upon engine speed and load.