Fuel pressure leaking down after shut off
1994 ZJ, 4.0L, 5 speed manual. This is my son's car and he has had it two years now. Since the day we got the vehicle it has taken several seconds to start. Always starts, runs great, but has always been a little frustrating. The fuel pressure is right at 32 lbs. but leaks down within 15 seconds after shutting the engine down. I am not one to throw parts at a car but this weekend we dropped the tank and replaced the fuel pump with the Bosch unit. We also replaced the fuel pressure regulator. Neither of these fixed the problem. I hate when that happens! Where is the fuel pressure leaking down. There is no sign of leaking injectors. The jeep idles smooth, has plenty of power, doesn't smoke at start up, doesn't smell of fuel. No signs of a leaky injector.
Could it be the plastic fuel lines? They have the original plastic clips and do not leak fuel, but they could be allowing air in the lines when there is not pressure. Is this something I should look at or is it obviously an injector because that is the only place it could be leaking down?
Just so you know the long story, this is the second pump we put in. We put a Airtex pump in last weekend and it pumped fine except the fuel gauge would not work, so we got the bosch pump. Neither pump took care of the leaking pressure problem.