My 1999 Ford Expedition (original owner, 99K miles, 5.4L, AWD) developed a starting problem about 3 months ago.
When the problem occurs, the engine cranks fine, but does not start (almost like it is not getting fuel). The problem is random in nature and does not appear to be affected by temperature or rain/humidity. Sometime, if I wait a undetermined amount of time (10-15 minutes), it will finally start correctly (though with some hesitation)like nothing was wrong.
Initialy, both my mechanic and I believed it to be a faulty fuel pump and this was replaced. The problem appeared to be solved until about a week later (after I brought it home, the truck sat without being driven)when it happened again. My mechanic looked at it again and cannot find any reason (no faults found with the computer codes, no visible corrosion on connections, etc)and the fuel pump is maintaining pressure in the system. When it does start, I can turn it off and start it right back up.
Any ideas would be appreciated.