Fuel vapour smell

Troubleshooting
1

Hi all, I have a JDM NA GTO. I’m hoping someone with more knowledge than I can give me a steer to save me from doing anything unwise!

I have a strong smell of petrol fumes/vapour at the rear right of my car by the wheel arch. It is immediately noticeable and has developed recently.

I would note:

  • I believe elements of my car’s EGR or vacuum system have been fiddled with. I know the vacuum line to the cruise control isn’t connected (if that’s relevant).
  • Rest of car and engine bay - No fuel smell near the front of the car at all or elsewhere around the car. None in the engine bay at the filter or the charcoal canister.
  • Boot access hatch - I have opened the access hatch in the boot floor and stuck my head just above it. There is no strong smell of fuel vapour like there is standing near to the filler/rear right wheel. I feel it’s important to say I really could not smell much if any fuel smell with my head down in the boot by the hatch.
  • Filler cap - I have inspected the filler cap which appears fine. I stuck my head right by the filler door and there is no strong smell in the filler cap area itself.
  • No fluid yet noted under car - I have looked under the car various times on dry days recently. I have not noted any liquid fuel or drips on the ground, just the smell of fumes.
  • Underside - I have got under the rear of the car and looked up. As with the fluid point above, I do not see any obvious drips or noticeably shiny petroly areas on the tank, filler neck or elsewhere. I have not removed the filler neck protector so far.

Looking at the workshop manual, everything I’ve described probably points to a vapour hose or line but I would appreciate any input people may have so I can go straight for the right area.

2

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Check the rubber house that allows air out the tank when filling with fuel- the smaller diameter one in this picture. It doesn’t take much to allow fuel vapour to escape- can be worth replacing some of the old rubber vapour hoses as they’re pretty old now.

3 Likes
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You haven’t really mentioned the general condition under the car. I have seen a number of the filler tubes completely rotten and leaking. Also check the rubber hose that connects the filler to the tank. If there is rust around the connecting points, vapour will seep through, especially on warmer days as the pressure builds up in the tank. Make sure you remove the plastic arch covers to get a really good look.

2 Likes
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Thank you both. I had the car up today with the wheel arch cover off, a bit cruddy on the whole but structurally sound. There is a little rust on the filler neck nearer to the top, the protector had 1 screw rusted away and the hose clamps near the tank are cruddy also (but not thoroughly rusted). It was dry weather and I couldn’t see any wet spots which would indicate obvious leaks in the area.

The vapour hose itself didn’t seem bad either but the clamps were fully browned. I’ve got some spare fuel hose and clamps so will replace that as a first call since it’s convenient then see if the smell persists.