Friday, March 21:
While running around 35 mph this evening, truck began to sputter and eventually shut down and would not re-start. Seemed like out of gas (guage showed 1/4) but adding 2 gallons did not resolve it. Tow driver was able to get it going by pumping the accelerator. After that, it ran and started normally the rest of the evening. No check engine light.

Tow driver suggested adding injector cleaner.

Truck has just 43K miles. Have owned it from new in 2005.

Fuel filter was replaced three months ago so, at least at the moment, I assume that is not the issue.

Sunday, March 23:
Truck ran OK one-way this morning, would not start on way back.

Zero fuel pressure

Shorted fuel pump relay contacts and fuel pressure slowly came up to 70 psi. This took maybe 20 to 30 seconds. Truck ran OK with this short in place and pressure remained near 70. Did not drive it, just idle seemed OK. Should it take this long to come up to pressure? Removing the short resulted in a very slow pressure reduction indicating at least to me there are no leaks.

Swapped fuel pump relay, still no start, no fuel pressure

There are no diagnostic codes.

Any suggestions on what to check next?

 

My guess, to fit the facts, would be that the check valve in the fuel pump assembly is going bad, or there is a leak in the fuel pump assembly hose.

Because it ran with fuel pump on all the time then inertia switch or wiring is not an issue.

The check valve holds 50psi pressure in the fuel system when pump is off, which is most of the time, even when driving.

The check valve is part of the assembly, never heard of replacing just that.

Removing the bed of the truck, if you have a helper, is much easier than dropping the fuel tank.
8 bolts, disconnect filler/vent hoses, and unplug tail lights.
Slide bed back or off, your choice.

9 years is an early failure for this.

 

If there is slow pressure reduction after removing the jumper across the relay, the check valve should be OK. A bad check valve should result in a fairly quick reduction in pressure. You can also cycle the ignition switch a few times to build up the pressure and the engine will start and run. It seems something is not activating the fuel pump relay but I don't enough about that system to make any suggestions.

 

Fuel pump relay is activated by computer via Grounding.

Computer controls most things by grounding, coil/spark, fuel injectors, fuel pump are a few.

So if engine sits over night it will start in the morning without turning key on and off a few times?

If not then it's the fuel pump assembly.

A leak anywhere else would be noticed by a fuel smell.

If it was a leaky injector, and leaking enough to stall engine you would also have reported lots of grey smoke out the tail pipe.

The electrics for the fuel pump relay are pretty straight forward.
Only 4 pins of the 5 are used.

In the socket with Key off there will be one 12v connection, that's the full time fuel pump power, it comes from it's own 30amp fuse in engine power box. This is one leg of the "load" on the relay

With key on there will be another 12v connection active now, this is the relay's "coil" power, the coil is what turns into a magnet and Pulls Closed the "load" contacts to pass power to fuel pump.
The other contact for the coil is to the computer, when computer grounds the contact, power flows thru the coil and it turn into a magnet and closes the Load.

The other contact for the Load goes to the inertia switch and then to fuel pump.

Fuel pump relay can be intermittent, any relay can, but these usually just quit out right when they fail, they are not very expensive.

Computer turns on and off the fuel pump relay based on RPM, speed, load on engine, and throttle position, these are preset parameters, I have never read/heard of a computer being the issue in a fuel pressure problem.
You could be the first, but I would look at other option before replacing computer, because it can not be tested only replaced.

 

New fuel pump is in place but I cannot seem to get the locking ring fully rotated. Ford has a special tool for this but does anyone know any secrets on this?

Also, because I did not know how to remove the fuel lines, I ended up breaking the quick disconnect for the line between the fuel pump and fuel filter. Are there any alternatives to replacing the line entirely? I have not been able to find a replacement for the quick disconnect elbows at parts stores. Should I expect a Ford dealer would stock a replacement line?

Thanks in advance.