Do I need a fuel pressure regulator (I think so) but where does it fit into the fuel system as my fuel rail has no return.

I'm planning on using a low pressure pump from tank to swirl pot mounted in the boot, then high pressure pump to the injector rail, I dont have a return line from the engine bay and don't want to try and fit one now its fully built.

I was thinking that I could "T" it in next to the pump and use the output of it to return to the swirl pot, would this work?

alternatively instead of using the pump I'd planned to (Flow Rate 180Ltr per Hour, 5.5 BAR Pressure) could I use the GSXR intank pump inline as it would be at the correct pressure, but will it struggle with the distance and trying to keep the pressure constant?


I've been looking at regulators and they seem to have a vacuum connection - what is this for and is it needed?


engine for reference is a 2.0 pinto with race head & cam, throttle bodies will be GSXR750.

[Edited on 19/6/08 by se7ensport]

If you are not going to fit a return then you only option is to Tee it in after the high pressure pump and return to the swirl pot. Not an ideal set up though.

The vacuum connection is to ensure the pressure drop across the connector remains constant, so a fixed injection pulse width always injects the same amount of fuel.

It's possible to dispense with the vacuum connection and just rely on the ECU mapping to get the pulse widths correct. This means you effectively have "bigger" injectors under high vacuum conditions such as idle, which means smaller pulse widths are required. If injectors are large to start with this could be problematic.

Rover changed to fitting an in tank regulator on the 75 models --- no vacuum connection, the return line is entirely in tank and goes back to discharge adjacent to the in tank pump suction (note not tee'd in ).

Obviously the ECU mapping must allow for this.

Just to add the reason for not feed back in via a tee to the return line is it could airlock and also to stop heat build up in the circulating fuel & pump.

Even with the Rover layout the big disadvantage I can see is if the tank runs dry the the fuel lines will be airlocked,

Would I be better off using the bike pump then and not using a regulator?