Things to check;
Air Compressor
Air Compressor Drier
Control Module
Height Sensor
Air Spring
Solenoid Valve
Also, check for hose leaks and any other leaks.
All of these things can add up fast in your pocket. Even having them checked will cost you an arm and a leg. I would suggest calling Strutmasters and ordering a conversion kit. You can do away with all of the air ride components and not worry about replacing any of them again. I replaced several units on my Expedition before I called them. I wished I had called them to begin with. I saved a lot of money and got my car fixed. I haven't had no problems since then. There is no more air nothing on my car! No more things to check when it goes low! I love it!
Have the a fuel pump pressure tested.
The electric fuel pump is inside the fuel tank
On a 1999 Ford Expedition : The ELECTRIC fuel pump is INSIDE the fuel tank * the sending unit for the gas gauge and the pump are installed through a round shaped access hole in the top of the fuel tank
Yes, that is possible.
The electric fuel pump is inside the fuel tank
I noticed that " Helpfull " had answered that the air suspension relay on a 1998 Ford Expedition was located on a bracket by the passenger side headlight . ( he came up with the answer after doing a Google search about 21 hours ago - was the answer not correct ? )
In the right front passenger footwell , behind the kick panel ( according to the 1999 Ford Expedition owners manual )
Either the air suspension relay that is behind the passenger side wheel well or the compressor.
dont know if its the same but i have an 2005 expedition and my fuel pump module was located in the rear driver side wheel well between the frame and the spare tire
Not that I know of. Yes see answer posted by "Lincolnator" on how to do this.
The air suspension switch is behind an access panel , in the cargo area , on the drivers side near the liftgate ( the fuel pump inertia / shut off switch is also there )
heater core....