L - Fuel System

A lot of mods here:

But first, the subject of Fire!

Q: What causes a fuel fire in an Elite?

A: Anything that causes petrol to run into the distributor which is directly under the rear carb.

When I first bought the Elite I was very aware of the warnings about petrol fires from Club Lotus.  Their advice was always focused on the replacement of the fuel line (from the flowlock solenoid to the carbs) with a braided line.  It is easy to gain the impression that this is all you have to do - not so!

My car had an engine bay fire caused by a fuel leak so learn from my mistakes!

!)  Install a braided line by all means but do all these other things as well

2)  By now many cars have lost the red metal tag attached to each carburetor that tells you to torque up the fuel line banjo to 17 ib.ft.  Make sure you do and be very careful about reusing the fibre washers.  In theory you should not re-use these washers, but if you do then make sure they are in perfect condition.

There is nothing wrong with the original plastic fuel lines used by Lotus.  But it is wise to replace something which could be 25 years old with a new line.  Remember though that a braided fuel line is merely a rubber fuel line with a braised cover, and it too will have a finite life.

3)  The Dell'orto carbs need regular rebuilding.  You can buy rebuild kits from Contact Developments in Reading (now in Tilehurst) as they are the sole outlet in the UK for Dell'orto parts.  The key parts are the float valves which prevent the top chamber flooding and the diaphragm for the accelerator pump.

Float valves: Buy from Contact Developments and you know you have the right parts.  If these valves fail you will flood the carb and fuel will spill out from the top vent which especially disastrous for the rear carb.  Note also that fitting a high pressure fuel pump can force the valve open and, again cause flooding.

Accelerator Diaphragm: This is the square multi-sheet rubber sheet that prevent fuel dripping out of the bottom of the carb.  Again disastrous for the rear carb.

The rebuild kit should be applied every 25,000 miles, but for most of that means 2 - 3 years.

4) Prevent a fuel leak running into the distributor.  I have made a metal plate that is bolted to the engine above the distributor.  Fuel leaking will run over the plate and down onto the engine block, and hopefully not into the distributor.  This plate is curved to follow the shape of the distributor and was formed by bending it around a wine bottle.  Perfect!  The shape of the plate is quite complicated and was arrived at by making a cardboard template and trial and error.

Mods:

Fuel Tap: Well worth doing so that any job can be tackled without spilling fuel.  The in-line tap is fitted in the fuel line just after the tank banjo and can be accessed from inside the boot.  Modern fittings are designed so that when the fuel line is inserted into the fitting, an internal clips secures the line and makes a leak proof seal.  This is complete magic because when you play around with these it just doesn't look up to the job, but they work amazingly well.  Now its easy to change the filter or service the pump without draining the tank or spilling fuel.

Fuel Pump: The SU Pump is another pile of crap so take away the worry of will is start, will it fail, will I have to tickle the contacts again and fit a modern Facet Pump.  These are virtually the same size and easily fit into the well in the boot left hand side.  The basic pump should be fine, but since I have a 2.2 litre engine and I don't want any fuel starvation I went for the red top version.

Fuel Pressure Regulator: This is a wise addition because the Facet fuel pump could be strong enough to force open the carburetor valves, so it is wise to be able to reduce and regulate the pressure.  I fitted a Filter King regulator.  You could fit one with a fuel filter built in, but I preferred the separate filter.

Fuel Filter: Plastic in line filters are a standard automotive item, but I have placed it in the well in the boot.   My original one was placed under the carpet such that the boot floor never fitted properly.  Is this standard?

Fuel line from the filter through to the Flowlock solenoid valve was completely replaced with new plastic fuel grade line.  Fitting new plastic tubing to the Flowlock is tricky.  Obviously it has to be heated up so that it will push on, but I could not get this right.  Apparently the trick is to heat the metal tube on the Flowlock valve rather than the tube!  The fuel line from the Flowlock to the carbs is a properly made metal braided line with crimped ends.

Carbs:

Not modified but there was a lot of work to get them tuned correctly for the 2.2 litre engine.  The original carbs were damaged by the fire so I bought another pair of second hand items, applied the rebuild kits, fitted new "O" rings and new Thackery washers. (Note: the original spring types are replaced by two metal cup washers and a rubber item that looks like a pulley.  Works the same way).  The carbs were fitted with the 2.2 jets as per the Lotus manual, but I also followed the advice of Contact Developments who are extremely knowledgeable.

It took a while to get the jetting right.  This was done on the basis that any flat spots were tuned out by changing jets, and the whole engine tune was possible for emissions, and the mixture  settings were in the right "band" (two turns).  Write to me if you want my jetting details. lotus75@btconnect.com

Tuning

I will write a whole section on this as I have it down to a fine art now.  I use a combination of Gunsen's CO2 meter, Colour Tune and a 4 tube manometer.  This item is superb.  It cost £50 and can be used to balance all four chokes simultaneously in real time.  It is a modern version of the old Mercury U tube design, where the Mercury is replaced by Stainless Steel rods.  This item is advertised in the Motorcycle mags and is purchased from a company in Northern Ireland.  Far better than listening down a rubber tube!

More on this to come.

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