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WRX convert to returnless fuel system

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I'm doing a fuel system upgrade on my 01 WRX with a EJ25 running a Haltech Elite 2500 and looking at converting it over to a return-less (dead head) fuel system tom simplify plumbing and tidy up the engine bay. I mostly use my car as a track car running on circuits.

Has anybody had any experience doing this on a EJ motor and what gotcha's should i be looking out for?

I'm already running a walbro 460 high pressure pump in tank, and looking to add a second in a surge tank in the engine bay to feed radium fuel rails with a fuel pulse damper.

Also what if anything needs to be done in the tune to support returnless?

I honestly cannot think of a positive reason to do this on a track car, is it purely for aesthetics you're wanting to do this?

Adding extra fuel tanks in the engine bay is going to create a whole lot of issues in itself, fire hazards being a major one.

Was thinking of going returnless owing to having two fuel tanks and the difficulty in balancing the feeds to and from the tanks. Another reason is to reduce the load on the battery/alternator (long story). The final reason was to potentially reduce fuel temperature (caused by the low and high pressure pumps circulating fuel unnecessarily).

You will need really a good fuel pressure sensor attached to the ECU. The ECU will also need to be capable of doing PWM control of some form of the fuel pump, possibly via a high frequency solid state relay or similar. The ECU will then need configuring to control the fuel pump.

If you are also fitting a surge tank with a fuel pump then that will need a high pressure pump and the pump in the existing tank swapping for a low pressure one.

You could do a return style that still had a dead-head to the engine. Just plumb the fuel pressure regulator near the fuel cell, and put a Tee to the fuel rail between the pump and the regulator. In order to maintain constant differential pressure, you will want to run a MAP pressure line back the the Fuel Pressure regulator.

So i think there's some confusion on what i mean by returnless, perhaps let me explain my plan further.

This is for a club level sprint car, not race car.

My fuel pump\s are already controlled via a Haltech PD16, so PWM control is already in place and piece of cake.

Changes are to:

Fit a surge tank in the engine bay, specifically thinking of this one http://www.radiumauto.com/FSTR-RA-Fuel-Surge-Tank-Regulated-P2768.aspx

Surge tank will have fuel feed from the factory fuel tank

And have a return line from the surge tank, back to the factory fuel tank via a flex fuel sensor

Then have a high pressure fuel pump (controlled by the PD16) to feed fuel from surge tank to a Y junction into parallel fuel rails with a fuel pulse damper in the rail.

In theory my understanding is that a return-less system is not MAP referenced, so runs at a consistent pressure. So the pressure sensor should only be require to detect potential failure of a component or run out of fuel and shouldn't be actually needed for the tune.

A non MAP referenced fuel system on a boosted engine is asking for trouble, unless the pumps are controlled to maintain the required Differential pressure across the injector. If there is not a way of maintaining the differential pressure, when the engine comes into boost, then the delivered fuel volume will decrease. This can be compensated to a point in the tune, you end up with a fuel map that looks like Ayers Rock when the manifold pressure goes positive and the duty cycle increases rapidly to compensate, but this will end up with either running out of DC or range on the table.

Thanks Stephen, thats what i wanted to confirm as i suspected there would be issues maintaining the appropriate pressure differential across the injector relative to the manifold pressure making the tune far more difficult.

hardware wise its fairly straight forward

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