New 01 3.0 ranger owner, It appears to me the fuel pressure is regulated in the tank, 2 lines between tank and fuel filter, single line to fuel rail, no return line ( that I see). So what is the purpose of the the device on the fuel rail with the vacum line to it?
Pulling vacuum line on running engine didn't change fuel pressure, stayed at 65.

thanks

 

It is the Fuel Pulse Damper and it looks very similar to the Fuel Pressure Regulator on earlier trucks. Pulling the hose from the FPD does not change the rail pressure.

A Mechanical Returnless Fuel System like the one used in a 98+ Ranger has an inherent problem with pressure variations in the rail caused by injection events. The Fuel Pulse Damper is tuned to help maintain a more consistent pressure throughout the entire rail.

The vacuum hose is just a failsafe measure intended to capture gasoline if the diaphragm in the FPD were ever to rupture. In normal operation, it does nothing.

Here is a comparison of a FPR and a FPD. These happen to be from 5.0 Explorer V8's of 2 different years - Ranger EFI is similar.

Fuel Pressure Regulator (Return Fuel)


Fuel Pulse Damper (Returnless Fuel)

 

The vacum line on my 01 3.0 has worn over time and is now just completely broken I've never had any problems with the truck will the broken vacuum effect the operation of the FDP. Even with the broken line I've had no problems didn't even realize it was broken till I changed the injectors

 

As I understand it, the Fuel Pulse Damper does not use vacuum during normal operation. Supposedly, the line is there as a safety device in case the damper should ever fail and leak fuel. Again, this is not first hand info so I can't verify it.

If it were my truck, I'd fix the vacuum line.

 

Thats the way i understand it to. the FPD is a fall back incase all hell breaks loose.
I wouldn't let anything go wrong on the Fuel delivery system, thats asking for trouble IMO.