Lotus Elan

Leaking fuel cap

PostPost by: simon.mitchell » Fri Jun 17, 2005 3:32 pm

When my Plus 2 returned to the road a few weeks back it quickly became apparent that all was not well with the fuel cap. Every time I went round a corner it was dumping fuel all over the new paintwork that I'd laboriously applied last summer. At Castle Combe the other weekend it seemed that I wasn't the only one with the problem, with a number of other plus 2's having dirty brown stains around to fuel filler. I worked out that the fuel was getting out through the breather holes in the cap.

Anyway, after trying a couple of unsuccessful temporary fixes including a bung in the filler neck(!) I think that I've finally cracked it. I've fitted a non- return breather valve into the filler neck and sealed up the breather holes in the cap with a couple of blobs of solder.

First impressions are good with not a drop having been spilt so far!

If anyone else is interested in doing the same the part you need is tank breather valve part number TBV45 from these people:


You just need to remove the filler neck, drill an 8mm hole to fit the valve and then solder up the breather holes in the cap. Make sure all of the rubber parts in the cap are in good condition while you're there. As a belt and braces fix I'm going to fit a pipe to the breather valve, loop it high up in the boot before exiting it though a hole in the boot floor.

Worked for me!
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PostPost by: john.p.clegg » Wed Dec 03, 2014 9:27 am

You could try one of these,I've got one on order and will report back...

http://www.mx5parts.co.uk/fuel-filler-r ... -2643.html

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PostPost by: Galwaylotus » Wed Dec 03, 2014 2:10 pm

I'd be careful about having a non-return valve as the only pressure equalisation. Installed one way and you can pull a vacuum on the system as the fuel is used. Installed the other way and the system gets pressurised in warm weather. There is a significant expansion of fuel in summer. I used to get significant overflow when I'd fill the tank almost full unless I took a reasonably long drive before parking.
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PostPost by: gus » Wed Dec 10, 2014 1:36 pm

The cap seal dies pretty quickly and I have replaced mine several times. I don't think the flip caps have venting, as the dual tank vents should do the job.
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