EFI plumbing

[LEETR4A]

Hi all

I'm about to plumb in the efi system on my TR7 V8. I will be fitting a swirl pot with high and low pressure fuel pumps close to the fuel tank, but as I've not done this before I have a couple of questions and hopefully someone must have done this before.

1. I plan on using a Sytec OTP017 high pressure pump rated at 201litre/hr at 3 bar, but not sure which electric low pressure pump to use before the swirl pot.

2. Where do I run the return fuel pipe to. The fuel tank has a new outlet in the base so can I run the return pipe to the original outlet by the float assembly or should it go somewhere else.

Thanks

Lee

[AndrewMAshton]

Hi Lee, I have Efi on my 4a, you will need a return on the top of the fuel tank, I have an aluminium fuel tank and bought a male boss which I had welded on, I used Goodridge fittings all round, -6 for supply and return.  I always thought the swirl pot was below the tank so filled by gravity so can't help with that one I am afraid, my fuel tank has baffles fitted so no need for a swirl pot, also I used the Bosch 044 or equivelent, my setup needs 5 bar, you will need a pressure regulator set at the required pressure on the return, cheers, Andrew

[TriumphV8]

If you want to use a swirl pot to provide fuel in a long corner with less fuel in the tank you must make sure that there is sufficient fuel in the pot for the whole corner while the low pressure pump pumps air and not fuel into the pot.

So it is unwise to return the overflow to the fuel tank as that is too much loss and will dry the pot very quickly.

At the bottom the high pressure pump must take fuel, in the middle the fresh fuel from the low pressure pump must come in and on top the air and overflow fuel must go back to the fuel tank.

As a hint I would recommend to use special rubber hoses like the Gates Barricade and use steel pipes where possible otherwise there might be a lot of fuel smell from the lot of rubber hoses in the trunk.

Take into account to use a MegaSquirt or similar with wideband AFR control and get rid of the air metering unit. I have that in my Rover V8 for 20 years and it is very reliable.

[LEETR4A]

Thanks for the replies guys.

The Sytec pump I am fitting is equivalent to the Bosch 044 so that should be ok.

The return fuel pipe will be going to the tank via the swirl pot, i'm just not sure if the return fuel should go in to the top of the tank which will be a pain as the tank is now back in the car or can enter through the original outlet which can be below the fuel level in the tank, but will be the easier option.

The rest of the efi system is standard Range Rover Classic 3.9 hotwire with a 14 CUX ECU that came with the engine although I will also be fitting a fuel pressure gauge as well.

[iani]

I thought it was preferable to have the return fuel go into the top of the tank as it is likely to be warmer than the fuel in the tank, it then mixes and cools before going back into the pump. My return line routes to the top of my tank via the original orifice.

 

[Stagpowered]

The return pipe on my EFi Stag engined TR250 used the original fuel oulet pipe as the return for many years until the original tanks sealing layer of fibreglass was eaten by the ethanol in modern petrol.

The alloy tank I had made to replace it has the return into the sump of the tank close to the outlet and has never given any problems

Neil

 

[Melcoagain]

The original outlet will have a filter inside the tank and should be adequate for EFI. If you use it as a return you risk filling the filter up with any **** missed by your inline filter. It will also protect your pump.

You can use your new fitting in the base for the return. Alternatively you can remove the plate over the filler hose in the boot and "Tee" into the breather line for a return.

Not sure why you need a low pressure pump.

 

[LEETR4A]

Thanks again for the replies.

I like the idea of using the breather pipe as the fuel return, someone else has also suggested that as an option plus it is easy to do.

I will use the extra tank outlet as it is a bigger diameter for feeding the low pressure pump and swirlpot and blank the original outlet.

The idea of the low pressure pump is more a belt and braces job to ensure there is always enough fuel in the swirl pot.