Unwanted smell of Petrol!!

[MJH2454]

First time Spitfire owner, there is quite a strong smell of petrol when driving, no evidence of petrol leaking in or around the engine bay, car runs perfectly so apparently not an over rich mixture, no smell of petrol from the engine by either. However lift the boot and you get a definite whiff of petrol, had the fuel tank cover off and again no evidence of fuel leaking, seal on fuel cap appears to be good as well. Where do I go from here ??

Forgot to add MK IV

[AndyTV8]

Try having a check of the state of the sender sealing to the tank ...could be coming from there

....... Andy 

[Adrian Cooper]

Plus one for Andy's suggestion and the rubber collar that joins the filler cap to the tank neck is another weak point, especially if you have an increase in smell after spirited cornering or just after filling the tank. You don't say which model of Spitfire you have but I believe that the later versions have a vent pipe at the top of the tank which can perish and lead to petrol smells. Someone more knowledgable will be along to advise on that I'm sure.

Adrian

[Anglefire]

The 1500 and possibly others has a vent on the top of the tank that is blocked off - mine was knackered and did exactly this - replaced and all sorted 

[dave.vitesse]

On the top of the fuel tank there is a breather pipe. On the UK cars this is blanked off with a rubber cap. Over time the cap fails to seal and allows the petrol fumes to escape.

Dave 

[Pete Lewis]

https://www.canleyclassics.com/?catalogue=triumph-spitfire-mkiv/1500&diagram=triumph-spitfire-mkiv/1500-petrol-tank-all-markets-except-usa

shows as 158554  but not available  many use some fuel hose with a plain shank bolt  & hose clip to plug it 

Pete

[MJH2454]

4 hours ago, dave.vitesse said:

On the top of the fuel tank there is a breather pipe. On the UK cars this is blanked off with a rubber cap. Over time the cap fails to seal and allows the petrol fumes to escape.

Dave 

Thanks Dave,

Been in there and you are correct, piece of rubber has disintegrated, so just attach a piece of blanked off pipe in it's place or longer piece of pipe taken through boot floor to under the car?

 

[JohnD]

Good idea, but not just through the floor.   In the unlikely but possible case on getting inverted, then the contents of the tank will empty onto the floor, causing an awful fire risk.

Three possibilities:

1/  Blank it off again.     Short length of hose, with a bolt screwed into the end.   Smear thread with fuel resistant sealant (Red Hematite)

2/ Fit a one-way breather valve.   This will allow air in, as the fuel is used, but not fuel out, in the unlikely but possible, etc.etc.

3/ Run a length of hose from the breather pipe, right around the tank in a vertical plane, and then out through the floor. That will let in air, but in the unlikely, fuel will run into the hose, but won't be able to get any further.

On fuel smell, that can permeate through the wall of a hose, in sufficient quantity to cause quite a niff.   It's worse with old hose ad new, alcohol fuel.     New Alcohol resistant (R9) hose may help, but the only thing that will abolish it is Teflon, steel braided hose.    That will clear your nose, but also clear your wallet!

JOhn

[dave.vitesse]

The petrol cap is said to have a small breath in it. But as John suggested I added a pipe and a one-way valve. The pipe  came out through the floor.

Dave 

[Unkel Kunkel]

On 05/06/2020 at 07:29, Pete Lewis said:

https://www.canleyclassics.com/?catalogue=triumph-spitfire-mkiv/1500&diagram=triumph-spitfire-mkiv/1500-petrol-tank-all-markets-except-usa

shows as 158554  but not available  many use some fuel hose with a plain shank bolt  & hose clip to plug it 

Pete

Or a central heating brass 8mm micro bore compression fitting  stop -end

[yorkshire_spam]

Technically you shouldn't use silicone hoses/pipe parts where they have contact with fuel, but this seems to have lasted since 2014 without issue: