Fuel Tank, Lines and Filler Cap

The rear subframe the fuel tank is bolted to is 2mm steel on a GEN III chassis.
The thread pitch on a 8mm metric fine bolt is 1.25mm. I'll leave you to dwell on that while I demonstrate how I attached the tank.

One could use a stainless steel bar the full length of each side and then secure it with as many rivnuts as you feel comfortable with. I took a lesson from Stuart Holden's excellent blog and used small plates over each tank tab with 6mm bolts into rivnuts.

The tank is raised into place using a jack and then held with four small G-clamps while I drill the holes and insert rivnuts.

Later when I fit the body I'll run some sealant around these brackets to stop water and dirt ingress and paint them black.



Fuel lines.
Decide what connectors you want to use before ordering your fuel pipes. If you use AN connectors get the fuel pipe to go with them. I have used push on hose connectors from Viper Performance. They also have an excellent page on their website that explains AN fittings and sizes.

For the fuel line clips, don't use Jubilee clips. They distort and can damage the line.
Here we are using Mikalor Supra Hose Clamps from Westfield Fastners.

Lastly the fuel line ends are finished off with some little black socks purely for aesthetic reasons.




The fuel pump is Walbro GSL392 an is fitted as close to the tank and as out of the way of the prop shaft as possible. It seems these pumps do not like a filter in front of them so flush and drain the tank before connecting up.
Before fitting the pump in this location, you may consider fitting the speedo sensor here as well:
18 Speed Sensor


The fuel pump bracket is a device from Motamec. The mounting holes are inline with the bracket so it fits nicely along the chassis rail. There are two 45 degree connectors to make the fuel line as straight as possible. I am told to not use 90 degree connectors, probably creates too much turbulence and friction in the fuel flow.

In fitting the mount and lines, consider the access to the clips etc will, in future when build is complete, be from below. So do things up with respect to being able to access them from below in future.

The line from the pump is secured above the lowest point of the diff hanger with a P-clip and a 5mm hex screw.



And finally the fuel line from pump to filter.


The filter comes with two large clips for mounting. They are designed to be screwed to a flat surface. I changed them for similar clips with a single hole for a mounting screw which means the clip keeps its shape when mounted on a curved surface.

Fuel Gauge Sender
The unit supplied from AK is a TB9011/KIT from Caerbont Automotive.
The arm which moves with fuel level needs a lot of trimming down. There is a table in the accompanying leaflet from which you could derive the correct arm length using some extrapolation as the depth of the AK tank (180mm) is outside the scope of the table.
Anyway, we want to measure it ourselves do we not?

So, rig the sender unit up on a board with a single screw holding it at the top of the board.
Draw a line 180mm (7" in old money) parallel with the board edge.
I fixed mine so the float is about 20mm from the line. That leaves a small amount of fuel when reading empty.
But also check the full level. Make sure the float is close to the top of the board - which will be the top of the fuel tank. If it is too low, the gauge will read full before the tank is.
So, this is how it's done:

Note the float will submerge by about a quarter of its diameter in water so take that into account when fixing the lowest level.
And yes I know petrol has a different Specific Gravity to water. If you want to take that into account, you need a holiday.
Solder the two arms together with the supplied clips. Run solder the length of the joint between the two arms.

Lay some grey RTV gasket or similar each side of the round cork gasket and secure with six screws. They are not equidistant so the holes only line up in one position.

But, do not put loads of gasket stuff on so that it oozes out, and absolutely DO NOT get it into the screw holes. What will happen is that you put the screws in, the RTV gets pushed in and drops into the bottom of the tank. When you run low on fuel it will get sucked into the fuel pump so blocking the flow. When you phone Jon up to ask him if he agrees with you your diagnoses that the fuel pump is bust, he'll tell you what has probably happened and call you a plonker. And let's face it, he'll be right.

Fuel Filler Cap

Later, when the body is fitted, we'll be wanting some way to be able to fill 'er up at the local gasoline emporium.

So, fuel filler cap and flange from Brasscraft. Where else?

The option is to glue it on or drill and bolt it down. If we screw it down we'll need some counter sunk screws. So drill out the holes in the flange to 5.5mm then use a proper countersink tool to grind out to a depth were the screws will sit slightly below the surface. If any sit even just slightly proud, the cap will not screw down into position properly. This is a bit important as when you set the location of the flange, it will dictate the final position when the cap is screwed down. And the cap has to be in a certain position to pass IVA - so I hear.

As we are screwing the cap down after the flange is bolted down, it has to have clearance around the the raised bodywork as it is turned. To facilitate as such, the flange has to be offset to the central position of the cutout. In my case it was 8mm rearwards of the centre position.









And here is the cap screwed down into place in what I understand to be the IVA acceptable position.









Next we need to connect the cap to the fuel tank. CBS sell a super flexible hose, 51mm ID and in 500mm lengths. Sadly you will need around 530mm - 560mm so order two which will come in a 1000mm single length.

The hole in the wall of the boot need not be too large if the hose does not pass through at a too acute angle.

The dimensions I have is: 63mm x 78mm and located 111mm fup from the floor of the boot.








And then lined with the off-cut of the rubber trim AK supply for the bonnet.

The hole for the breather pipe is separate and is lined with a rubber grommet.





There is now but a small gap around the filler hose that will be filled with black rubberised sealant.

Breather Pipe

Discuss.

As fuel is used, air needs to replace it or we get a partial vacuum.

With changes in ambient temperature, fuel can expand so air needs to get out or we get positive pressure. So we have a breather pipe, but what to do with it.

One can purchase an inline breather/vent valve. This device will allow the fuel tank to 'breath' and some of them have a device to stop fuel leaking out in the event of the car being upside down. Newton and Mocal make them and you can get them from Merlin, Demon Tweeks etc.

But that isn't quite what AK do. The solution here is to connect the breather pipe into a 'T' piece in the main fuel inlet pipe (AK will flog you one). The 'breathing' then takes place through the fuel cap which actually isn't air tight.

Four small holes are also drilled into the small internal locking fuel cap to aid this air flow.

You may wish to consider that as we now have a closed loop between the breather pipe and the main inlet pipe that the breather pipe is now a bit redundant. It is, apart from the fact it also helps to get air out of the way when filling the tank and helps to stop back pressure when the fuel is going in.

I have set mine up accordingly, so we'll see.