Fuel tank vent

[Sidcoupe]

Is the fuel cap supposed to be vented as when I’ve gone to open the fuel cap you have to pull but you also hear the tank popping

[h20hamelan]

Are there vent holes under your cap

Fuel needs to be replaced with something

[Sidcoupe]

There’s no vent holes the centre plate moves

[types26/36]

Yes it should be vented.

[Sidcoupe]

Just drilled the hole it will stop noises coming from the petrol tank only got the car yesterday there’s quite a few things needing fixed it was supposed to be perfect

[alan.barker]

Sid,
Just to confirm you have an Elan and not a +2.
Alan

[RichardHawkins]

Sid,

As luck would have it, I am about to fit my new fuel filler cap (S4 Elan FHC) there is no hole in mine either. However, the part of the fuel cap that you mention as moving is quite a slack fit, which I would have expected to act as a vent.


Richard Hawkins

[smo17003]

I also remember having to drill a hole in my new S4 cap when I fitted it last year. The old one had the drilling.

The (original) cap on my S3 project is also drilled, but the centre plate is held with a peened over stud, not a screw or split pin.

Pure guesswork here, the caps for Elans and +2's appear to be the same (they're certainly the same part numbers on SJS's list). Because the +2 has a different tank breather system I don't believe it needs the drilling in the cap.
It's just a shame that the suppliers don't tell us this stuff.

[Gordon Sauer]

Yes, my + 2S 130 is not drilled and I presume it’s because it has that big tubular recovery tank over the fuel tank and the early +twos had those lines that went up through the roof or something so maybe with those reliefs for the fuel tank, none of the +2s needed the drilling, Gordon

[fatboyoz]

Hi Sid,
Ceandess, is still operating today.
https://ceandess.com/shop/?wpf_fbv=1&wp ... r_cat_0=46

The raised annular pressing in the cap is the cap vent. The caps with no hole are not vented. The caps with the hole are. When I purchased a new cap, many years ago, it had a visible hole, but the tank was always under a vacuum when time to refuel. I dismantled it, and discovered that it did not have a hole on the other side. The holes are supposed to be 180 degrees apart, top and bottom, to allow venting, but not to allow fuel to slop out.
If you have drilled a hole straight through, you may have some leakage after refuelling to a full tank.
Cheers,
Colin.









quote="Sidcoupe"]Just drilled the hole it will stop noises coming from the petrol tank only got the car yesterday there’s quite a few things needing fixed it was supposed to be perfect [/quote]

[Sidcoupe]

It’s a lotus elan se s4
Drilling the hole seems to have stopped the tank noise so thanks for that , seemingly the car has not been used for 15 years plus, the other problems are main beam and dip headlights don’t work , lights don’t pop up , horn parts missing on the steering wheel , fuel gauge doesn’t work , the solid drive shaft conversion the rubber boots are off at both sides, I’m sure I will find other things it was sold as a perfect car but in fairness I never saw it before I bought it as it was 500 miles away

[smo17003]

Hi Sid,

Here is a thread that explains the headlamp vacuum circuit viewtopic.php?f=38&t=21376 - it should be the first thing to check before you start looking at the lighting electrics. There are microswitches on the headlamp pods that "switch on" the lamps as they are raised by the vacuum. Get the pods working and the electrics might sort itself out. If it's been stood 15 years then hopefully the problem is in the pull switch or perhaps the non-return valve. If you're really unlucky you might have a leak at the tank due to chassis corrosion.

A tip for a new lotuselan.net member is to use the "bookmark topic" button at the bottom of the page. This saves the topics of interest for future reference. Find them again by clicking on "forum profile" (top right of page), and then find "manage bookmarks". Basically you are creating your own reference library.

Mike