Fuel Filler Cap - to vent or not to vent....

[alan.barker]

My theory is that the problem isn't so much that the filler cap leak, it's more that the filler cap are being lifted by the weight/force/pressure of the fuel when Corning. Allowing some fuel to leak out.

The mx5 mood works by peventing that force being transmitted to the filler cap, there for the cap stays seated and no fuel leaks.

I plan to do it to my car at some point but don't keep much fuel in it so not an issue for my usage and there fore not a major priority.

+1 with 50 Litres in the Tank plus cornering that's 50Kilos pushing the Seal off it's Seat.
Alan

[Chrispy]

Yep! I tried new seals, additional tension on the seals, lubing them and all sorts. Only thing that worked was keeping <1/4 of a tank of fuel, or the MX5 filler valve. I can fill the tank to the very top and zero leakage now.

And that pissy litle hold in the cap would not be enough to allow the amount of fuel I had coming out of mine that's for sure!

[JonB]

My experience of the MX5 mod was different. Basically, it didn't work at all. So I cut a piece of sheet rubber into a circle the size of the fuel pipe and screwed it to the underside of the cap. Result? No more leaks, even if the tank is full.

Of course, this is a temporary repair until I can find out why the MX5 valve is not working properly. I suspect it's not fitted right. When I got the rubber pipe reducers I found that they didn't actually fit in my tank's pipe, so I had to bodge it into the rubber elbow section. That's probably why it wasn't a successful installation.

[alan.barker]

Hi Jon,
Good to hear your comments.
I'm sure one day when you're feeling zen you will have a flash of genius and it will work.
It took me 40 years of tinkering on +2 Elans before i saw the guiding light with the MX5 Mod.
I hope you decide not to sell your +2 they are so good to drive, almost as good as my Sprint.
Alan

[JonB]

Hi Alan

[off topic]
Thanks for the kind words. You'll be interested to learn that I pulled the Car & Classic ad yesterday, although this had more to do with the lockdown than wanting to keep the car. That said, I may carry on with it for now. If the propshaft firm was still trading I'd have sorted that, but I do not want to immobilise the car indefinitely by removing the prop right now. I do have the radiator fan wiring to fix (it's developed an intermittent fault) and I might revisit the fuel valve installation.. it all depends on whether I need (and can obtain) parts.
[/off topic]

[john.p.clegg]

" I might revisit the fuel valve installation "

I hope you've not fitted it reversed?

John

[JonB]

Of course not..!

[alan.barker]

Are you sure, we don't want you eating Humble Pie
Alan

[john.p.clegg]

OK , I'll admit to fitting it the wrong way round...only found out when I went to fill up....It took quite a while...

John

[DJW]

[JonB]

Tell you what, I’ll feel a right tit if it turns out I did put it in back to front.

I mean if Cleggy can do it...

[HCA]

i have a brand new one that you could have. I have done the mod and it works David

..new cap or new MX5 valve? Do you still have it? I'd be interested either way - I should insert an MX5 valve whilst I have the tank out and my Monza filler is a bit pitted.

Let me know please?

thanks
Hal