Actually, that's not quite right. The fuel pressure shouldn't drop at all for at least 10 minutes. In fact, it shouldn't have dropped more than 10 psi over night. In order for fuel injection to work, the fuel has to be pressurized, and most people wouldn't understand the idea of waiting a few seconds for the pressure to build up when they start it, so the plan is to keep the lines pressurized all the time. When the pressure starts to drop after only 3 minutes, you do have a problem. It could be either of your suggestions, or the pump itself. For that matter, it could also be a crack in the rubber portion of the pick-up.
If you remove the vacuum line to the regulator, and it has no fuel in it, then the regulator is most likely fine. The method I use for determining if it's the injectors or the pump is a home made tool. I took an old fuel filter, and cut off the inlet and outlet tubes, and inserted an piece of rubber fuel injection hose in between them. To check for where the pressure dropping is coming from, I install this tool inline where the filter normally goes, turn on the pump, and then crimp the rubber with a pair of vise grips, and then turn the key off. If the pressure continues to drop as it did before, that I know there is a leaky injector. If the pressure now remains steady, I know the problem is in the tank.
Good luck!
Take care,
~Chris
|