Petrol Smell

[MK IA Norway Viking]

Good morning - I have fuel odour in the boot of my car and it is seeping into the passenger compartment. Mine is a 3-litre MK IA. Fuel hoses are old but seemingly intact / no cracks. What is the likely culprit ? The main/reserve tap o-ring ?

[Eric R]

I experienced that. I found the rubber seal under the fuel cap lid needed replacing - fixed. Make sure the overflow pipe is not obstructed.

[Phil Nottingham]

There is no reserve tap on P5 3 Litres. The Mk1 and Mk1a were notorious for it and it was only a partial improvement on Mk2s although ours is good. The M3 and P5s had a better arrangement.

It is most likely the cap seal but the filler neck hoses can become porous so not good for E10 fuel?

[lagain]

The seal for the fuel cap is poor. When mine leaked several decades ago I went to Halfords and saw a radiator cap that came with a circular thin sort of washer. It was perfect to stick on the underside of the cap and she has not leaked since. If the underside of the cap is turned it does not seal properly so check that it is seating on the filler evenly.

[dhb5610]

I've been struggling with this for ages with my P5B and can't find it. the smell is in the boot and there are no apparent leaks it's frustrating to say the least. I will report on any further progress

[MK IA Norway Viking]

Good morning gentlemen, and thank you for the kind advice/sharing of experience. I shall test out these various points and report back to you. The fuel we have in Norway is still with 5% ethanol in it; as petrol is a global commodity I expect that E10 will also slip in to our local market. So, in any event, I will replace the various fuel hoses in the boot with hope that this will contribute to "cleaner air" 

Wishing you all a nice weekend.

[percy]

1) Assume you have removed the panel in front of the tank and checked all connections? There are quite a few connections large & small.
2) Is the fuel cap seal in good condition and not spilling any fuel with a full tank on sharp right hand turns. This tends to run down the boot gutter and cross the seal especially if the seal has seen better days.
3) Is the fuel cap water drain pipe in good condition, clear and exiting through the hole in the boot to the road?
4) Is the small breather pipe by the spare wheel cradle in place/ not blocked?
5) Is you engine running rich and exhaust being drawn into the boot by vortex action?
 

[MK IA Norway Viking]

Thanks for the good points !!!

1. All hose connections in the boot are tight and fine.

2. Fuel cap seal is the domed version, and it has some cracks.

3. The drain hose is intact and runs through the hole in the boot.

4. Breather pipe from boot into the spare wheel well is not checked

5. Engine running OK, however smell develops also when car is standing still - for instance, when opening the boot lid the smell of petrol comes out.

6. I suspect the issue could be with the ventilation / breather system in the double skin above the tank OR the culprit could be a bad o-ring in the solenoid device switching between main and reserve tank

7. It could simply be that petrol travels through the rubber hoses. I plan on renewing those in case there are cracks or bad sections I have not noticed.

[percy]

Norway Viking, sorry I should have been clearer, I was replying to dhb5610 as he has a P5B. I don't know much about the early P5's fuel system.

[dhb5610]

Thank you Percy most of what you mentioned is fine. The smell is definitely in the boot, however it is also there when driving, the engine is running really well however the mixture could need adjusting i'll get it checked Thank you

[Sam Bee]

If you have or are contemplating nitrile rubber hoses be aware that it will allow passage of petrol vapour.

[djm16]

with my MkIIb, whenever there has been a petrol smell, it has been coming from the double pump. There is an overflow pipe about 1/8" going from one side of the pump only through the floor of the boot to take away petrol that leaks through the rubber diaphragm.

I think I eventually fixed the recurrent leak past the paper gaskets in the pump by spending some hours flattening the mazak spacer between diaphragm and valve body, then reassembling with anaerobic sealant (silicon will decay, and hylomar blue will leach its plasticiser in petrol).

If you have the car outside in a mild breeze, you should be able to localise the smell to drivers side / near side / high / low.

[MK IA Norway Viking]

Good morning, and this is terrific advice. I shall definitely see to this as well !

Happy Rovering !


Kindest regards,
Christopher
Oslo
Norway