Petrol Smell

[D Murton]

For the past few weeks I have been suffering with a smell of petrol.

So far I have replaced all the underbonnet flexible fuel hoses (all of which looked OK) & the rubber hose between the filler cap & tank (which was well past its best). I've checked the mechanical fuel pump & that seems OK.

I thought I'd cured it until today.

Today when doing a very sharp right hand turn with a lot of right foot again a very strong smell.

I'm fairy sure that its not the tank as I've removed the boot board & interior trim & there is no smell from this area.

Could it be high fuel level in the float bowls causing fuel to come out of the overflows.

The carbs are HS6 AUD209 so there is no obvious way of adjusting the float level.

 

If anyone has any suggestions I'd be grateful

 

Thanks

 

Dave

[littlejim]

On the run from the tank to the petrol pump there are (on mine anyway) a couple of short sections of rubber hose. On mine these were not fitted with hose clamps. They are now. During my fiddling with the fuel pump and fuel bowl fittings I managed to work the foremost bit of rubber tubing loose.

Would recommend having a shoofty at them (the rubber bits) just to make sure they are not loose or perished.

They appear as #50 in the Moss cattledog diagram for the fuel pipe system.

[Andrew Smith]

Dave

 

I had a similar problem on TRK which has HS6s fitted and it turned out to be a perished float bowl gasket which was difficult to detect at first as the petrol kept evaporating(!!) , so worth checking these little chaps.

 

Moss provide the gaskets, so an easy fix.

 

Good luck.

 

Cheers

Andrew

[riverstar]

I have the same problem. When the car is stationary there is no petrol smell at all however as soon as I start driving I can smell petrol and when I park it is very strong for five minutes but then dissapears. I have checked everything over and can't find any leaks and my carbs were recently refurbished. I did suspect that it was comming from the tank but would have thought that the wind when driving would leave the smell behind also if parked in the sun I would have expected to smell petrol when the tank heated up.

[RogerH]

Mr Riverstar,

if you have a convertible, the wind will blow forwards when driving forwards. With a surrey top not so defined.

 

Roger

[Ade-TR4]

Hi

Check the gaskets as suggested.

Also check the needle valves are seating properly and not being held open by crud: There are newer "delron" tipped needle valves that seem to be a bit more tolerant of minute bit of crud.

Also, it may be worth checking the fuel pump pressure. If it's putting out more than a few PSI, it may be overpowering the floats and flooding the carbs.

Cheers

Ade

[Badfrog]

My experience in the field concurs with most posts: it's almost always overflowing carb bowls:

 

1) excessive fuel pressure (no more than 3 psi). Buy filter king regulator, set at 2.5-3 psi

2) leaky bowl gasket

3) punctured floater

4) poorly adjusted valve actuators. If you have the full plastic floaters, change for those with metallic arm.

5) crud blocking the valve open

 

Alone or in combinations.....

 

Been there, done that, ruined the T-shirt....

 

Badfrog

Edited July 21, 2010 by Badfrog

[Ade-TR4]

I've fitted this in-line regulator: All OK so far...

http://www.fuelpumpsonline.co.uk/sytec-flo-pro-fuel-pressure-regulator-carburettor-1-5psi-30-p.asp

 

Cruising at Higher revs on minimal throttle or on the over-run with throttle closed seems to cause the standard pump to overpower the floats.

 

You may see some yellowy staining, from evaporated fuel, down the sides of the float bowls (usually the rear-most).

 

Cheers,

Adey

[TorontoTim]

All of the above is great advice and places to go hunting.

 

However, don't rule out the tank - especially if the smell is in any way related to how full it is. Take a look at the flexible hose linking the fillr cap to the neck on the tank and check for cracks/age and also tightness of the Jubilee (or similar) clips holding the hose on.

 

Tim

[Steve Priest]

All of the above is great advice and places to go hunting.

 

However, don't rule out the tank - especially if the smell is in any way related to how full it is. Take a look at the flexible hose linking the fillr cap to the neck on the tank and check for cracks/age and also tightness of the Jubilee (or similar) clips holding the hose on.

 

Tim

 

 

I had a leak from the tank. Turned out to be the gasket (or lack of) on the fuel level sender located on the top of the tank. If the tank was more than about half full, petrol sloshed against the top and leaked out. The sender had been fitted with what looked like a bit of cardboard from a cornflake packet! The correct cork gasket is easy to get hold of and solved the problem.

[D Murton]

Thanks all

 

New float needles & gaskets have been ordered & I'll have a crawl underneath this weekend to look at the pipe from tank to pump.

 

It never occurred to me that the original pump could create too much pressure for the float needles to cope with.

 

Thanks again

 

Dave

[MikeF]

Thanks all

 

New float needles & gaskets have been ordered & I'll have a crawl underneath this weekend to look at the pipe from tank to pump.

 

It never occurred to me that the original pump could create too much pressure for the float needles to cope with.

 

Thanks again

 

Dave

 

 

Hope not too late, but I went all throught the above and finally solved by buying a pair of Gross ball valves for float chambers to replace the SU types. Takes about 5 minutes to swap them in and the result is immediate. Cheap too at less than a tenner. Had big impact not just on smell, but also on carb setting and economy. May not be the same for you, but my carbs are less than 3000 miles from new, so you would not think new valves should do anything.

 

The adjustment on the float chamber arms is to bend them, you can do this with your fingers and by eye or follow the instructions in the manual. I bent them so the fuel level was about 2 cm from top of chamber. Later when I measured properly I found no further adjustment required.

 

 

MIke

[Ade-TR4]

Be careful with Grose jets: Some work perfectly, in others the ball bearing binds in the cage and locks partly open! Viola: worse flooding than ever

On later HS6s, the float height is factory set (I seem to remember). Early ones can be adjusted as Mike says.

Cheers

Adey