Fuel Tank for Injection Engines

[Josh]

Hello everyone, I have a few questions regarding fuel tank manufacture...

I'm using a 2.0 Silvertop Zetec running my own Megasquirt EFI / ECU.

What fuel pipe should I use for my feed and return lines? Should it be rigid or flexible?

I'm using a standard Mondeo fuel rail, what fittings will I need to push onto this?

Which fuel filler caps would people recommend? I'm still undecided as to whether to leave the filler on top of the tank or route it to the rear bodypanel. If I was to route it, how have others done it?

Can anyone suggest a suitable swirl pot and pump to operate at ~180bhp @ 4bar? And will I have to incorporate a sump into my tank design?

What have people been using for a fuel level sender for the gauge?

Sorry for all the questions, thanks in advance for any replies!

Josh

[PorkChop]

Most of the fuel lines can be rigid, but you will need flexible tubing where movement or vibration can be a problem e.g. into the inlet manifold and fuel pump. This has to be marked as suitable for carrying fuel.

[alga]

My 2¢.

I ran an 8 mm copper pipe inside the transmission tunnel, 8 mm fuel hose elsewhere. I used a brake flaring kit to make beads on the ends of copper pipe. Fuel hose comes in low-pressure (carb) and high-pressure (efi) varieties.

There were pieces of rubber hose on my Mondeo fuel rail. In the middle there were some smart metal-plastic joints that require a special tool to open. I just obliterated the plastic part and was left with a nice 8 mm steel tube to connect my hoses.

I have the "budget" (60 quid, yeah, right, "budget") aero fuel cap from the group buy (like this: http://www.cbsonline.co.uk/product/B...minium_AERO694). I have it mounted on the rear panel and joined to the tank with a 90 degree silicone hose bend. Filling in is fiddly, I have to drip fuel in at very low rate, otherwise it's splashing out and the pistol cut-off is kicking in.
My cap is positioned like this:


I just integrated a ~13x13x7 cm rectangular swirlpot to my tank. That's 1 litre of fuel, should be good for 10 km or so ;-) The hole from the tank to the swirlpot is about 1-2" in diameter and is central to the pot. The intake is also in the swirlpot's bottom center, and the return comes to the swirlpot rather than tank. I had no fuelling interruptions with this setup even with the tank near-empty.

Since I use the Sierra cluster for now, I used the Sierra's sender, too. In the carbed Sierra, The sender sits on the fuel pickup pipe. I cut out a part of that pipe and made an adapter for the 6 x ø60.7 (or what's that standard fuel sender PCD) fiment. The length of the float arm fit the book tank almost perfectly.


I hope this makes sense.

[Josh]

Thanks for the info Albert, plenty for me to digest!

What thickness and grade aluminium did you use to build your tank? I have enough 2mm ali left over from my floor sections to fold the main section of the tank, but I'll need to source more to make the end plates/baffle/swirlpot.

In your build photos I see you've placed a gasoline filter in the fuel feed line (I think?) Would you suggest I use one too? And what is the the item mounted next to it?

Thanks
Josh

[K4KEV]

An inline fuel filter of some sort is absolutely essential do not leave it out unless you want never ending trouble with either carb or injection

[alga]

I used the leftover 2 mm half-hard. People commented that it's overkill. And, yes, 2 filters: the tin can one after the pump and the cheap plastic one before the pump!

[Wynand]

Originally Posted by Josh

Can anyone suggest a suitable swirl pot and pump to operate at ~180bhp @ 4bar? And will I have to incorporate a sump into my tank design?

Since my tank setup have rubber hoses in at the rear, changing to copper through the tunnel and back to plastic exiting at the front firewall, I decided on the following system to eliminate high pressure in the fuel line from the tank that can leak (fire risk) at the joints in the line.

At the tank I installed (any suitable place) an inline low pressure pump that move the petrol to the front and dump in a surge tank. At the surge tank I have four nipples fitted for;

1. return fuel line to tank when surge tank is full (on top)
2. Return fuel line from fuel injection rail (on top)
3. Supply from the low pressure pump at the tank (top side)
4. Supply to high pressure fuel pump (bottom) which result in the fuel pump always gravity primed in my setup

The beauty with this is that the fuel line to the surge tank is open ended so to speak and now pressure in it which is safe (just circulating and no pressure in the surge pot). The only high pressure pipe is the little distance from high pressure fuel pump to injection fuel rail. Another plus with this is the fact that the high pressure pump cannot surge cornering etc.
The con is you have to have two fuel pumps.

See this picture taken from my car's setup.

[Josh]

Thanks for the info. Interesting set-up Wynand. I've already gone and got an in-tank fuel pump from a Mondeo so I'm going to go with that, just make sure my connections are strong enough to take the pressure.

One last question - how have people done their tank vents? Will a one-way valve be enough to allow air to enter the tank as the fuel level lowers, or does it need to be two-way to allow for expansion of air on a hot day?

[alga]

I'm pretty sure it must be a two-way affair. It must allow air in when the petrol is being used, and it must allow air out for thermal expansion. I just used a 1 m length of fuel hose, from the right rear corner, where the breather port is in the tank, it runs up to the chassis, then left towards the opposite corner and down. Previously it used to be just up and down, but that used to spill fuel on heavy cornering.