Resolved How does a FPR work?

[DeathBeast]

I have the Walbro 255 HP pump, and I keep reading that you need a FPR with this setup:
-How do you tune a FPR?
-Does it make a difference to have the fuel pressure gauge in or outside of the car?
-How exactly do they work? (Give me the for dummies breakdown)

Thanx,
DeathBeast

 

[MikeyboyTSi]

To set an adjustable FPR, you just disconnect the vacuum line to the FPR, and turn the adjustment screw on the regulator (in for higher, out for lower) until you get the pressure you want.

It's doesn't matter if it's inside or outside the car. Mechanical gauges are more accurate than electric ones. In order to use a mechanical gauge inside the car, you *should* use an isolator.

FPRs work like ball & spring boost controllers. You set the initial displacement on the spring with the adjustment screw. At a certain fuel pressure, the spring force in the regulator is overcome, and the diaphragm moves off the seat and bypasses fuel, thus regulating the pressure.

 

[DeathBeast]

How do you know what the pressure you want is? Datalogger?

Thanx,
DeathBeast

 

[MikeyboyTSi]

Desired fuel pressure varies with injector size, airflow, timing advance curves, etc. My guess is, that with the knowledge level of your questions, you should just be running stock pressure. Get it from the FSM.