I own a 2002 ford eplorer sport, 2 door with a v-6 engine.
Recently, it has started acting up. Every so often, it will refuse to start.

It will crank correctly, but there is a lack of fuel.
Startng fluid will start the car SOMETIMES for a time, sometimes until
the starting fluid runs out (quick squirt).Totally unreliable. It will sometimes
start, sometimes not, without regards to length of time running or engine temperature.

I checked the electrical to fuel pump and can hear it running.
I have changed the fuel filter and gas cap. I am prepared to change the fuel pump.
It is later model 2002 fuel pump with plastic tank and has return fuel line.
While I attached a pressure gauge to the fuel rail the first time, there was no pressure,
zero. I towed the vehicle home, and the next morning it started up without doing anything.

One strange item. While running a fuel pressure test, ( 68 psi while running ) I noticed
the release valve for the pressure gauge (attached to fuel rail) would let out fuel
WITH AIR BUBBLES. Is there supposed to be any air in fuel rail, or could that be causing
a vapor lock, not allowing fuel into the injectors ?
Any help would be appreciated...
Thanks, DHSVCS

 

You will not get a vapor lock with modern fuel injected systems. Those days are gone. I wouldn't be concerned with the fuel bubbles. Push fuel out a shrader valve at high pressure will cause that.

You changed the fuel filter which is what I would have done. I would check for any stored codes first. 68 psi sounds high to me. Make sure your fuel pressure regulator is good by pulling off its vacuum line and looking for fuel. Lack of vacuum to the FPR can drive up pressure but I don't think that's causing your no start. If you have verified the lack of fuel pressure, having the proper voltage driving the fuel pump, that would point to a faulty pump.They can be intermittent.

 

Many a good fuel pump has been replaced because the proper tests were not done.
Just because there is no fuel pressure, does not always mean the pump is defective..
If the fuel pump is not getting the signal to run ,,,,it can't run and produce pressure..
Power to the fuel pump and good ground connection must be verified before condemning any pump motor.
Different vehicles utilize different methods to energize the fuel pump motor and you need to know which system you are checking and how it works.
A capable scan tool would be most helpful here.