Fuel Pressure Regulator Location

[cps13]

Hi

I am going to put an FPR on my locost build. I am a bit confused about the location. I know it has to be up by the rail but from the reading I have done it seems people have put them on the output/return end of the rail. I would have thought it would go before the input end so that it regulates the flow before it gets to the rail/injectors.

Please can someone confirm?

thanks

[stevieturbo]

The regulator can go anywhere after the pump, it doesnt really matter.

You can flow through the rail, into the reg and then out to the tank, or you can tee the reg off before the rail and run the fuel rail as a dead end, as many modern cars do now, although their regulator is actually inside the tank.

There are pro's and cons to each, but doesnt really make that much odds either way. The more common approach is to flow through the fuel rail and then to the reg.

[PaulKemp]

If fuel injected most rails will be controlled by the back pressure so the FPR is after the rail this maintains pressure in the rail to all injectors
If carbed then FPR can be after the pump in the boot or close to the carbs your choice

[stevieturbo]

PaulKemp said:

If fuel injected most rails will be controlled by the back pressure so the FPR is after the rail this maintains pressure in the rail to all injectors
If carbed then FPR can be after the pump in the boot or close to the carbs your choice

It can be anywhere after the pump. Most modern cars have dead end rails with a single line from tank to engine, and their regulator is in tank.

The most common setup is with the FPR after the rail, but it certainly doesnt have to be that way.