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Is soon as I developed a little speed on the AutoX or track days I have been plagued with fuel starvation issues, always having to keep the tank very full was a pain.

My first attempt was to fill the tank with foam, that helped a little but was not even close to solving the problem. So a surge tank was the answer, it's a square tank with check valves on three sides. They come setup for a remote pump, I just made a little bracket to mount my fuel pump inside the tank. I then used foam to hold the tank against the front of the gas tank.

Sounds easy but the first problem is getting the surge tank into the gas tank, it would not go through the stock opening on the top of my RCI gas tank. So I had to cut a larger hole in the top of the tank and use a blanking plate. Cutting the hole was easy, so was getting the surge tank in, the tough part was all the bolts on the blanking plate, I could only just reach inside via the stock filler hole to tighten all the bolts. But I managed to get it done, I also added a perforated stainless pipe so the foam did not block the filler hole and allow my dip stick to still work.

I got all parts from Pegasus Racing, they are real racers and just understand the problems we have, there tech support is great and have got me out of a hole many times. Here is a link to the surge tank https://www.pegasusautoracing.com/produ ... oduct=2538

I also got some foam from http://www.ksrfoam.com/ they do military tank foaming, fighter planes to tank, they sell off cuts at very reasonable prices.

Graham

$200... I'm sure it works great, but sheez.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Consider running the fuel returning to the tank (if you do) into the surge tank, else it may get pumped dry when the fuel level is low. The right way is to run that hose in such a way as to not cause bubbles, which can get sucked up by the pump and pushed to the engine.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

external swerl tank is the best way with the injection pump fed off it and an "in tank" low pressure pump to supply it with fuel.

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this story shall the good man teach his son,
and chrispin chrispian shall ne'er go by,
from this day to the end of the world.
but we in it shall be remembered.

Graham
If you have clearance under the tank I would look at adding a lowered sump for the fuel pump. You can fab a small box for a lot less then $200. I extended the sides of the sump up into the tank for about 4" and added hinges over ports to allow fuel flow into the sump from the sides. DaveW

Dave, I like your solution, if I ever have to remove the tank I will do exactly that.

KB58, the return line does run down into the tank, it was luck more than judgment, but it worked out that way. It was not cheap, but I only had a few days to make it happen and get it tested before a track day on Monday, so it's going to be worth ever penny if Monday goes by without a hitch.

Graham

The bottom surge tank is indeed the simplest and cheapest way, but isn't possible if the tank is already as low as possible, which it should be for CG reasons.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

In case it helps someone, I did a post on how to use an OE in-tank pump that has a fuel bucket and a jet pump built in.
viewtopic.php?f=27&t=11744

Not as pretty as the race stuff though

Hope the track day went well.
Cheers.

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Build log: viewtopic.php?t=9291

The big test was a track day yesterday at Autobahn CC. It worked perfectly so I am very happy. I did run the tank until it started to splutter just to see how low it would go, and there was barely any fuel on the dipstick. So I consider this problem solved. I also had a great time at Autobahn, the weather was perfect, the new LSD, wheels, brakes, light flywheel all work great. The LSD really allowed more corner speed, I was going a lot faster at the end of the day than I had gone in the past. There was another older Caterham (70's or 80's) at the event, another British guy from the Chicago area, it was a race only car, twin cam powered, but he had a transmission issue, stuck in gear. So he went home early and I was not able to get any move info, but a real nice race patina car.

Graham