97 SEVILLE IS HARD TO START, AFTER LONG PERIODS OF SITTING (6 pLUS HRS) SOME BACK FIREING IN EXHAUST IS NOTICEABLE, BUT ONCE IT STARTS IT WILL FIRE UP EVERYTIME I TURN THE KEY. I HAVE PRESSURE AT THE INJECTORS AND NO CHECK ENGINE LIGHTS OR FUEL LEAKS.
How much pressure at key on after sitting, make sure you have no liquid fuel in the vacuum line from the pressure regulator. How old and what kind of plugs are in the vehicle? And has this happened over more than one tank of fuel, could it be a fuel quality issue.