Fuel system cdesign

[Mat Grant]

Hi all,

I'm fitting a 1UZFE into an old Lotus - the car did not have fuel injection before the engine swap. The engine is fitted in the chassis.

I'm trying to get my head round the fuel system. I've tried searching the forum but couldn't find the answers. Has anyone got experience of fitting the 1UZFE into a car that didn't have fuel injection?

I've seen some designs that use 2 fuel pumps, a low pressure one in the boot and a swirl pot and high pressure fuel pump in the engine bay, 4 connections on the swirl pot, to and from the fuel rail, and to and from the tank.

I've also seen a design where the return off the fuel rail is plugged up (blocked off) and a single high pressure pump is fitted in the boot with a regulator, and the regulator is providing the fuel rail pressure, and the return to the tank is via the regulator. Then a single fuel line is run under the car, to the fuel rail input.

Does anyone know if the latter design will work with the 1UZFE? Or which would be better - or more importantly - safer???

Does anyone have any diagrams of the standard Soarer fuel system?

Any suggestions or advice appreciated.

Cheers, Mat.

 

[Zuffen]

THe 1UZ fuel pressure regulator runs off manifold pressure. As you will know this varies fom (about) -22psi at idle to zero at WOT.

The simplest system I've seen is to run a low presure pump form the standard tank to a swirl pot (2 litres is plenty) the fuel is then drawn from the swirl pot to the high pressure (EFI) pump and sent to the fuel rails.

The rails return the unused fuel to the swirl pot.

Any overflow from the swirl pot is returned to the fuel tank.

How I set mine up was the lowest outlet of the swirl pot ran to the EFI pump.

The second lowest was the fuel return the the standard tank.

The top fitting was the return line from the rails.

THe inlet from the standard tank was the 3rd highest inlet.

Seemed to work fine and I never had fuel supply problems.

Anther option is to purchase an EFI tank if one is available at a reasonable price.

 

[Mat Grant]

Hi,

Thanks for the reply! So if I'm reading your post correctly you have the two pump system? Did you mount your swirl pot and EFI pump in the boot (trunk) or in the engine bay?

Sorry for the dumb question, but where is the fuel regulator on the 1UZFE engine, is in internal to the fuel rail? Or is it in the boot with the fuel pump?

From the sound of it I need to run two quality high pressure fuel hoses under the car from boot to engine bay, then I am covered, whether the swirl pot goes in the boot or in the engine bay.

Thanks, Mat.

 

[Tonyd]

Hi Mat,

The fuel pressure regulator is in the fuel rail in the LS400.

I've put a swirl pot in the AK Cobra fuel tank into which I have fitted the standard LS400 in tank fuel pump running at a constatnt 12v . I have plumbed the return fuel line to a return feed into the tank so that the returned fuel feeds into the in-tank swirl pot. This means that you only need one feed ( which you already have in place) and one return line, one standard LS 400 fuel pump ( which is matched to the engine and ecu), and a bit of alteration/ fabrication to the standard fuel tank. A lot less joints, and no swirl pot visible or requiring placement. Plus with just one pump, and thats immersed in fuel, the installation is almost silent.

The swirl pot in your case could be anywhere but I would hesitate in putting a 2 litre potential bomb, with lots of potential leaking connections and pipe joints inside the engine compartment. I'd keep it as close to the fuel tank as possible.

Just my 2 cents worth.

Cheers,

Tony

 

[Zuffen]

My swirl pot was in the rear with the fuel tank.

I don't have a boot so it was in a body void separated from the interior by an aluminium panel.

I ran one HP EFI line to the fuel rail and used HP EFI line for the return which went into the swirl pot. You don't need HP line for the return (as it isn't under pressure) but for the minimal cost I would fit it anyway.

The swirl pot overflow went into the top of the fuel tank.

Running an intank pump requires a swirl pot or sump in the tank to ensure the pump doesn't suck air when cornering or under accelaration/braking.

My new fuel system has 2 Bosch 044 pumps in parallel with separate feeds to each fuel rail with the opposite end of the rails connected to the FMU that then feeds back to the tank.

I had a sump installed in the tank that's 2" deep to ensure constant fuel supply.