Sunday, May 13, 2012

EFI part 1 - The Fuel Tank

My GT6 was born with twin Stromberg carburettors. They're simple, reliable and moderately tuneable. More distinguished species of Triumph, however, had Lucas mechanical injection. I thought about fitting it, but getting the tuning right seemed to involve shims, shuttles and springs... not to mention running three times widdershins around a church at midnight for luck. Not for nothing is Lucas known as Prince of Darkness.

The modern solution is electronic fuel injection... as fitted to every new car. The first part of the conversion was the high pressure fuel pump. Some conversions use an external pump, fed from a surge pot (essentially a small second fuel tank) by a booster pump. I didn't like that much fuel-filled plumbing 12 inches from my left buttock, so opted to have a surge pot and injection pump fitted inside my tank. Tanks Inc ( sell kits for just this purpose.

Here you can see the Walbro pump and filter, and the small tray which acts as a surge tank to prevent the pump running dry on corners. The white nylon pipe is the fuel return, so that if the tank gets really empty, the surge tray will stay full as long as possible.

I had the tank converted by Greg of Fuel Tank and Radiator Specialists here in Brisbane. They fixed my Herald tank a couple of years ago after ethanol petrol ate through old epoxy repairs. Greg cleaned the tank and welded in a sunken section for the pump to bolt up to. It was pressure tested and returned good as new. I shouldn't have to worry about fuel leaks or dirt in the fuel system when the car returns to the road.

The surge tray was installed sideways for two reasons. Firstly, if it had been positioned fore-and-aft it would have interfered with the fuel gauge sender arm. Secondly, the car will probably be subjected to greater G-forces from cornering than acceleration or braking.

And here is the finished article, having passed inspection. The recessed pump fitting means that the boot floor will still lie flat. The wiring and two fuel lines are the next steps.


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