is it possible the flex fuel sensor could be restricting fuel pressure to the fuel rail ? when I first try to start the truck in the morning its hard starting and runs like its running out of gas for about 3 minutes then starts running great again.Had injectors cleaned at dealer 6 months ago and did tune up and replaced fuel filter yesterday and did not help at all. just curious about sensor before I buy a fuel pump. fuel pressure test results first time I turn the key on 20psi second time 35psi the third time 60psi even when I cycle the switch its hard start

 

A would say no on the Flex fuel sensor, never heard of it restricting fuel flow, and restricted fuel flow usually shows up at higher speeds, i.e. vehicle can't maintain 60mph, it loses power as fuel flow tampers off and pressure starts to drop, you would also get Lean Codes for both banks.

Fuel rail on '99 Ranger should have minimum 55psi for months and months if it sits, so you have a leak in the system, it is losing pressure when pump is off.

On the rear of the fuel rail is the Pulse Damper, it has a vacuum hose attached, remove this hose and check it for fuel, if there is fuel then replace Damper.
Fuel would be leaking out and into the intake via vacuum hose causing a "Flooded" engine condition so a hard start.
A leaking fuel injector could do the same thing, pull out all the spark plugs and have a look at each one, if one is blacker than the others then I would suspect that injector is leaking.


There is also the Check Valve on the Fuel Pump
Have a read here: https://www.ranger-forums.com/genera...-valve-146886/

Sageport thinks debris was holding open his Fuel Pumps check valve so he was losing pressure, while he did have to pull out the pump he did fix it without having to replace the pump