Lotus Elan

Fuel tank / petrol smell

PostPost by: Erwillia » Sun Apr 11, 2021 4:38 pm

Hi
When I purchased my lotus Elan plus two it had a very bad smell of petrol coming into the cockpit. I have connected the two vents to each other and the filler pipe and then also connected them to a one way breather check valve but I am still smelling fuel. What are the latest thoughts on the breathers should I reinstate the 2 breathers looping over the rear screen - this doesn't seem right to me

A further problem is the twin webers which have leaked fuel into the engine bay through the gasket when trying to start once - do these just need a new gasket or is there something more serious.
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PostPost by: Donels » Sun Apr 11, 2021 9:37 pm

There’s lots of information available on the site on fuel tank breather and what to do with the pipes to fix the smell. Just type in fuel tank breather into the search function.

Ref the leaking Webers. Any carb fuel leak is serious as the distributor is immediately under the carbs so a fuel fire is a big risk. There could be several different causes for the leak, from split O seals, loose carbs, stuck needle valves, in addition to leaking gaskets. You need to isolate the electric to the distributor then see where the leak is safely with no sparks. It may be necessary to remove the carbs and check/ replace all seals etc.
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PostPost by: mbell » Sun Apr 11, 2021 9:56 pm

The breather mods are to reduce the fuel smell out side of the car. It's still common to get fuel smell in the car and it's not really addressed specifically by the mod unless a lot of care is taken.

Unfortunately the fuel vapour can escape past the not very good stealing surfaces on the main pipes, breather pipes and possibly even the sender. Also care needs to be taken with section of material as porosity of the various hoses can also allow the fuel vapors to escape through them.
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PostPost by: LaikaTheDog » Mon Apr 12, 2021 9:12 am

This is a repeat of info I read myself when addressing the same problem;

The breather pipe goes over the rear screen so that in the event of a roll, the fuel won't just pour out.

I found that I had to use proper SAE J30 R9 fuel hose for my breathers as cheap eBay hose quickly allowed fuel smell to return.

If you have fuel bypassing your Weber to manifold seals they will also be leaking air and causing rough running so need checking properly, the rubber rings have probably cracked. Any fuel leak is very bad thing in a Lotus.
I have multiple extinguishers and a blazecut in my engine bay.
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PostPost by: gherlt » Mon Apr 12, 2021 11:01 am

Donels wrote:Ref the leaking Webers. Any carb fuel leak is serious as the distributor is immediately under the carbs so a fuel fire is a big risk. There could be several different causes for the leak, from split O seals, loose carbs, stuck needle valves, in addition to leaking gaskets. You need to isolate the electric to the distributor then see where the leak is safely with no sparks. It may be necessary to remove the carbs and check/ replace all seals etc.

I would add as possible cause: too high fuel pressure, mostly from electric fuel pumps.
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PostPost by: Erwillia » Tue Apr 20, 2021 11:00 am

Thanks guys for all the useful comments. Connected breathers together and to the filler pipe. Fills really good. Cap is vented so put check valve in vent line to allow air in. Alot better but still some fuel smells.
I have got mechanical fuel pump and no carbs - may have over pressurised it when trying to start from cold. Will replace all seals on carbs. Many Thanks
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