Fuel pressure regulator prevents pressure build up. When it fails pressure drops, not builds up. So that story seems suspicious.

You need to get OBD2 dongle 327 bluetooth device, and download ForScan app on your phone.

Then plug dongle into OBD2 diagnostic port, connect to the app, and check the error codes.

After that report here what codes its throwing.

Next step is to go into live data Dashboard screen, and setup to view the following PID's:

Voltage (11.5+ while cranking)
Engine RPM (gotta turn ~ 200rpm+)
Injector opening in Milliseconds (~ 2.xx+)
ICP (~ 500-700PSI)
IPR (~ 15%)


These readings in live Dashboard mode (while cranking) will show you whats not working correctly

Without the above free app (ForScan Lite) and $15 dongle, you are at a mercy of dealer or mechanic

 

 

Did you try to unplug the ICP pig tail?

 

 

Unplug the ICP and try starting with it disconnected

 

Does the engine crank normally but just doesn't seem like it tries to start? Does it sound like it's trying to "catch" (injectors firing) but just quite get all the way there?

There are some specific parameters that the PCM is looking for before it gives the green light to the IDM to fire the injectors (these are all minimums while cranking):

1. Engine RPM - 100
2. Injection Control Pressure (ICP) - 500 psi
3. Injection Pulse Width (PW) - 0.6 ms
4. Volts - 7-10 VDC

There are nuiances between years but these are the four basic things your truck PCM needs to see while cranking before the IDM gets the go ahead to start injecting fuel.

You can see that fuel pressure is not one of those. Of all the years I've had my truck and problems I've come through, fuel has not been one of them...especially too much. Your shop's diagnosis does not make sense. I'm not knocking them but I don't think they are very familiar with the HEUI system on the 7.3L. The fuel pump sucks fuel from the tank and fills the fuel bowl. The fuel system is dead-headed after that in the rail. The only path is through the injectors. The fuel pressure regulator (on the outlet from the fuel bowl) maintains pressure in the rails (~60-ish psi). When the rail is at designated pressure (based on the spring in the regulator) fuel sits in the bowl until it is needed. Fuel is never pushed back (as man-o-war mentioned), it just sits in the rails until used.

Unless you can access those parameters above you will either be shooting blind or at the mercy of a shop (I recommend a different one than you've been to).

If you want to read some more here is some good stuff from Oregon Fuel Injection, Inc.: https://cdn.oregonfuelinjection.com/...diagnostic.pdf

 

 

When you crank, does the tach needle move up? If not, you have a bad CPS (crank position sensor). I would put in a new one and try again. If it fires up, that's it. If not, you have a spare CPS to keep in the glove box. You'll need it some say. They fail every 5-15 years. Crank no start, tach needle not moving.

 

 

You can rebuild IPR for $15 , look into that kit and there is YouTube video that explains the process. Stuck IPR or unplugged IPR connector or missing IPR castle nut will not allow engine to start

Also, eBay ICP is garbage, and many many CPS you can buy in parts stores are garbage as well. Ask me how I know

 

 

 

If your are not building 500 psi ICP (high pressure oil) then the IDM won't fire the injectors. It will seem like their not getting fuel because the truck isn't letting any fuel into the cylinder.

Anything's possible (fuel, oil, etc.) but they pulled everything out, drained the rails, and put it back together. Most of the issues I've read about end up being high pressure oil.

How many times have they cranked the truck? I know when I replaced my injectors I sucked out the cylinders (injectors out and glow plugs out), hand-cranked the engine several revolutions (injectors in and glow plugs out), did several 10 second "dry" cranks with the 42-pin connectors disconnected (injectors in and glow plugs in), then plugged everything in and tried to start it. It was definitely a long start but it started on the first try (the cell phone on my windshield is running Torque Pro and the upper right "gauge" is ICP):

https://www.ford-trucks.com/forums/1...l#post17810730

I've read of people having to do several long crank sessions (no more than 30 seconds) to fill the rails and build enough pressure to fire.

 

When you crank, does the tach needle move up?