Lotus Elan

Plus 2 petrol smell

PostPost by: Dieschelan » Mon Nov 05, 2018 8:04 am

Hi

I know that the fuel smell is a common problem in the plus 2. Before I started the restoration of my plus 2 I had the same problem. Now I have a new aluminium tank but I don’t know the best way to solve the problem with the petrol smell.

Best Regards

Diego
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PostPost by: mbell » Mon Nov 05, 2018 10:21 pm

There a lot of information on here about re doing the tank breathers so that you don't have two large breathers venting to atmosphere which is biggest issue with +2.

You probably want to do that and replace/update all the rubber connections with modern ethanol safe rubber while there.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: DavidLB » Tue Nov 06, 2018 11:12 pm

If you search the archive on here there is a mod using an MX5 non return valve in the fuel filler and venting the tank back to the filler neck i've done this on my 130/5 and it works although the tank fills slowly
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PostPost by: gus » Wed Nov 07, 2018 1:35 am

The only thing you need to do is join the two vents into one.

two vents creates airflow across the tank and fumes.

join the two just above the tank, loop one line above one side vent and down rather than over the headliner

done
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PostPost by: alanr » Wed Nov 07, 2018 6:28 pm

Hmm.. This is interesting! Like Diego I am also interesting in solving the fuel smell issue on my +2S130 and the idea that gus has put forward I haven't heard before and seems a much easier a fix, if it works, than the filler pipe and MX5 non return mods.:D
It would be interesting to hear if others have tried this and how successful?
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PostPost by: mbell » Wed Nov 07, 2018 8:44 pm

Personally I joined the vents in the middle, added large vent to filler and added narrow vent to atmosphere inside one of the original vent tubes. Seems to have done the trick but I've not put more 1/4 tank in my car....

The tank needs wide vent pipes to enable filling, as the filler enter half way up you need a method to allow the air from above the filler neck entrance point in the tank to vent fast enough to allow the petrol in quickly. So you need to keep a wide vent somewhere for filling which makes it easy for the fumes to escape if that is a permanent vent to atmosphere

The other purpose of the vent pipes running over the roof is to stop fuel escaping in a roll over. If you have a vent that just loops up on one side of the car it maybe possible for the fuel to leak out via it in a roller over situation. Which isn't very desirable.

The method I used is the tried and tested method used for years. If you go this route you can also use purposed design valve on the narrow vent line that only vents at high tank pressures, allows air in under normal usage and provides roll over protection.

A MX5 valve can be added to the filler neck to address full spillage from the filler neck on to the body under cornering.


So you If you just join the two vent tube together the top of the tank is sealed and the air can't escape which is likely to cause you problems filling the tank past ~1/2. I haven't tried it like this so can't vouch that this is the behavour you'll see
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Bigbaldybloke » Sat Nov 17, 2018 12:59 am

I’ve done the mods on the vents, the bit that stops fuel running out if you happen to roll your car is the fact that the vent lines finish in the wheel arch below the bottom of the tank (with the car the right way up!). Hence if the car is upside down, these pipes are above the tank so fuel won’t run out.
Mine still has a slight smell of fuel and I’ve found that it seems to be coming from the banjo fitting to the new alloy fuel tank has the tiniest weep from the fibre washers used on the bolt. I plan to change them out for alloy washers. It can’t be coming from anywhere else as I only put a couple of litres of fuel in the tank.
Change is inevitable, except from a vending machine!
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