3.0L takes about 30 sec to cold start, then idle is hi & rough, stalls changing AT gears. No leaks found. Once in gear, with pumping gas pedal, runs smoothly to 60mph..New fuel filter, spark plugs & wires. CEL off. Can hear fuel pump click on with key to acc, & pressure remains zero for the 30 sec then slowly rises. Pulled sending unit & indeed fuel pump works with 12v applied. Screen has very little debris. I have no way to measure pressure directly from fuel pump, but gas flow is adequate to run my V6 to 60mph. Can anyone explain why my low fuel flow only occurs at cold start & idle? & why is my CEL not on for this issue? (does work, since thermostat stuck open code came up & replaced it) Thanx in advance...

 

Rangers have no fuel pressure sensor so there could be no CEL for low or 0 fuel pressure at start up

Below is assuming you do NOT smell gasoline anywhere around the vehicle or in engine bay, i.e. a leaking Fuel Line

1996 Ranger has 3 things that hold pressure in the fuel system when key is OFF
1. Inside the fuel pump is a check valve, a back flow preventer, basically just a flap that is pushed open when pump is on and closes when pump is off, the fuel pump is capable of 80+ psi fuel pressure

2. FPR(fuel pressure regulator) is on the engine, it is hooked to the fuel RETURN hose, this is a spring loaded valve, the spring pressure holds the valve closed until about 43psi fuel pressure, then its pushed open and fuel is sent back to the gas tank until pressure is below 43psi
FPR has a vacuum hose attached, this pulls on the valve against spring pressure, at idle/high vacuum, this stabilizes fuel pressure at 30-35psi while engine is running, this is done so fuel pressure doesn't go up and down as fuel Demand changes

3. Fuel injectors, obviously a leaking injector would cause loss of pressure with key off, but it would also cause Rich running, very low MPG and sluggish engine, so low on the list of possible pressure loss points

Ford fuel systems only Prime the system for 2 seconds when key is first turned on, that adds about 10psi to existing pressure, its a safety thing
The 1996 fuel system should hold pressure at 15-20psi with key off..............for MONTHS and MONTHS
So the 2 second fuel pump run time would be plenty to get good pressure

Try cycling the key on and off 3 times, so 30psi, and then try to start engine

Test the FPR first
Cold engine
Check its vacuum hose for gasoline, shouldn't be any of course, if so then replace FPR

Remove the Return fuel line from the FPR
Put a towel/rag under the FPR's fuel line connection
Cycle key on and off one time
Check to see if gasoline came out, it shouldn't until pressure is above 40psi at least
Cycle key on and off 2 more times, check again
If no gasoline came out FPR should be OK
If gasoline came out then replace FPR

If FPR checks as OK, the issue is the check valve inside the fuel pump, its not a separate part

1998-2011 Rangers used a different Returnless system, just FYI, 60psi pressure, so this systems info wouldn't apply to your 1996 system