Petrol Fumes

[Guest Gizmo]

I keep getting (usually when tank is low) petrol fumes in the cockpit whilst driving.

Once this starts we are talking strong smells! not just a whiff.

Not there when car is standing, no smell in the garage. Car has to be (or very recently been) moving.

Checked and replaced all flexible pipes in the engine bay. Had the carb off, cleaned gaskets (all ok), float level checked and reset (I have the official settings on DGAV 32-36 and DGAS 38 carbs if anyone wants them).

I am absolutely certain there are no leaks, so I am working on the fact that this must be vapour.

The tank takes pressure/vacuum (I get a "hiss" when I remove the cap) so I don't think it's from there.

I have a chrome Piper-Cross filter and all unwanted pipework has been blocked off.

Crankcase breather hs been replaced.

 

Anyone got any further suggestions, 'cos I am right out of ideas ???? (apart from dropping a match under the bonnet as suggest by one area sec who shall remain nameless !).

 

I should add that this is a series 3a with a 2ltr Pinto.

[Big Jim]

The tank takes pressure/vacuum (I get a "hiss" when I remove the cap)

Nothing to do with the smell of petrol, but it shouldn't do that, this means that you tank breather isn't!! this can cause all sorts of problems. I'll not go into the remedies, as it was on this board only a couple of weeks ago.

 

Right the smell of petrol. This has to be a leak. Places to check:...

Where the fuel lines go into the engine bay, under the side "lip" of the chassis.

The connections around the sender unit in the boot.

The grommet and surrounding area of the filler kneck.

Last but not least, the fuel tank itself. you don't need much petrol to cause an awful smell. The boot floor on the monocoque cars carries the rear of the diff, and it's just not strong enough, so in time the boot floor collapses at the back, this alters the angle of the tank mountings, then the tank starts to rub on the rear panel of the boot, thus causing leaks. I know! I've just been there!

 

good luck

[Guest Gizmo]

Hi Jim,

Thanks, I feel much better now ... not !

 

I will take a look at the boot floor next week (break for short hol.) but I don't think I have that problem yet. Mine is a 3a (RHSC's SVA special) so I have a few differences to the earlier models (not all good!), particularly at the rear end.

Just in case though, how did you strengthen your boor floor?

 

As for the tank pressure issue, I am sorry but I missed the notices you mention. Is there any way I can get the "back issues" ?

Cheers G

[Big Jim]

here are a couple of threads that talk about fuel tank breathers etc. To find this sort of stuff, just hit the "search" button at the top and put in a "keyword" eg. "fuel tank" "breather" or whatever else you can think of, and it will come up with all the posts with that word in.

 

I found that my tank was rubbing on the rear panel of the car & leaking, I lifted the carpet in the boot, to find the boot floor had been "pulled down" by the rear of the diff (equal & opposite forces etc when doing wheel spins & doughnuts!)

I took the tank out & got that sorted. Meanwhile, I jacked the boot floor back into it's proper shape, then made a 1" angle iron frame with a 3mm plate between to go into the boot & take the weight of the diff, with 2mm outrunners from it to pick up the front fuel tank supports. it's all nice and strong now.

It's a mark 3, which is probably the same as yours, if you're at Donington, ask me, and i'll get the carpet out & show you.

[Guest Ianz]

Jim

 

I've got a 3a ,and I,ve put a sheet of 3/4 ply in to cover the whole boot

floor and bolted my diff through that!!!

 

Seems ok to me!!

 

Cheers Ian

[Big Jim]

I,ve put a sheet of 3/4 ply in to cover the whole boot

floor

 

What you building then, a Morgan!

 

Wood! Noah should have been the last person to use wood to build transport! get some scaffold in there!!

[Guest Andy Rathbone]

i'm Sure its been said before on this board Noah was an amature working alone and the titanic was built by a team of experts.

 

Noahs boat was wood and the titanic wasnt

 

just an observation

[Guest Ianz]

Whatever!!!!!!

 

I do'nt have any probs ,with my floor collapsing!!!!!!!

or petrol fumes for that matter

 

Cheers Ian

[Peter Bell]

Gizmo, just a thought, if your tank filler hisses when you open it then apart from the fact you need to vent it, it also means it is not your tank that is leaking cos' it would suck air in if it was! So the leak must be else where.

Peter

[Guest Andy Rathbone]

my boot floor is also ply although not a structural part its SVA approved now too

and dont smell of petrol either.

 

gizmo it sounds like you have a leak someware along your fuel line

(just clutching at straws realy, sorry )

[Guest Alasdair]

Wood! Noah should have been the last person to use wood to build transport!

De Haviland did a pretty reasonable job with the Mosquito though.

[Peter Bell]

Don't forget Marcos! their early ones were all wood and the nice 1800 etc ones had wooden chassis.

Peter

[Guest micky bigthumbs]

it might seem silly but i had a brand new 2ltr Siera which went back to ford several times with fuel smells they tried everything , finally they found the filler cap had dust in the little hole next to the locking key and did not vent properly the cleaned the filler cap with a Pin and it was ok after that.

[Guest Gizmo]

Thanks to all. Just back from hols, and the first thing I did was start stripping the boot out. I really cannot find a leak, but the pressure in the tank (thanks Jim, I thought this was normal until you mentioned it) may well be the problem. and after Micky's last comment i reckon the lack of venting is causing a pressure build up in the tank that is finding a very small gap in the seals and blowing fumes into the cockpit..

I'll let you know as soon as I have it all to bits.

 

Sorry to read about your cracks Jim - hope you get it fixed soon. I tried searching for hits on "venting" without luck. If you happen to find any please let me know, else I will drop "Mat d Rat" a line and see if he has any archived...

[Longboarder]

This is what I did. Little hole in the fuel cap. This would leak if i roll the car. You are supposed to put in a vent tube from the top of the tank that has a free flow air valve but that stops fluid flow (get from demon tweeks, etc) or a loop of tube going as high in the car as possible and then exiting, open, below tank level.

 

Nigel