Petrol smell

[Edmason]

Having got the Stag back on the road I noticed a smell of petrol today which I can’t locate the source of. I’ve checked all the fuel line connections, but I notice that the overflow pipes from the carbs simply discharge at the front of the engine, rather than running back to the tank. Is that as Triumph intended?

[wilf]

Yes, it is.

[MikeParker]

There is a small blocked-off tube from the top of the tank that has a knack of getting unblocked-off. The smell then permeates the whole car. I had that for several years before bunging it up with a piece of rod.

[jbuckl]

Wise to replace the tank to filter pipe with a single piece of nylon.

As mike says for tank pipe blocking off.

Filler cap seal is also a favourite.

Check fuel pressure & delivery…. If it’s too high it’ll find a way out…..and stink!

Check stromberg choke discs for weeping fuel…. They do. And can be awkward to stop weeping.

Check, check and check again for fuel pipe security / integrity.

Carry a good extinguisher or two.

Ensure they are easily accessible.

Have recently seen sad pics of a stag that probably had not had these things attended to.

[Stag About Town]

How old is the tank? Stag tanks tend to develop pin holes underneath which may not be obvious apart from the smell until they result in a serious leak when the corrosion develops. Mine flooded the garage with petrol when this happened when I was away on holiday. Bought a new tank and a battery isolator after that scare. Also, the vent pipe under the car can give off fumes sometimes. John

[NorthernLad59]

I also have a petrol smell, though mine seems to be around / in the boot. Following jbucki's list I checked the filler cap seal. I have a brand new shiny filler cap so the seal is perfect. However I spotted that below the filler pipe there is a small drain hole that goes to a stub pipe into the boot. Presumably this is to drain water out of the filler cap. On my car there is no pipe connected to this. Should there be one and where does it go? Anyway it's made me realise that both times I've filled the car up with petrol the pump didn't cut out in time so petrol spurted out into the filler cap and over the rear wing. Presumably petrol also went straight down the drain hole into the boot. I'm leaving the boot open and the garage door partially open to see if the smell eventually dissipates.

[badenstag]

Maybe this old threads with images are of any help:

https://www.socforum.com/forum/forum/stag-owners-club/soc-forum/13425-petrol-tank-vent-pipes

https://www.socforum.com/forum/forum/stag-owners-club/soc-forum/26013-pipe-from-fuel-filter-in-the-boot

[gowerboy]

Check the banjo connections on the fuel pump, the petrol smell on mine came from there I got new nylon seals from LD Parts, solved the problem

[Edmason]

Julian says "Wise to replace the tank to filter pipe with a single piece of nylon."
Do you mean replace the entire pump to underbonnet filter with a single nylon pipe? From the Rimmers diagram it looks as if that line is in 3 parts joined by short lengths of fuel hose?

[jbuckl]

Yep the pump to filter… all in one piece of nylon.
no rubber until the filter to carbs.

Add a reflective shroud where the pipe is close to the left silencer.

May require a few new clips .

nylon to banjo just needs heating to push on.

after the filter, use high quality rubber hose and matched size high quality stainless fuel pipe clips.

[richardthestag]

Mk1 stag had a single length of nylon* pipe, however the tight radius at the base of the engine bulkhead was replaced with a short length of rubber fuel hose on most mk2 stags that I have seen. Often missed when replacing all fuel lines with new. also on the oe setup this fuel hose section was not clamped to the nylon, it was just a push fit. not really ideal so I clamp them using double ear hose clips.

Using very gentle heat on brand new nylon pipe you can create reasonable tight bends and do away with hidden and inaccessible joins under the car.

Tell tale for any issues in the boot area is that the interior of the car stinks of fuel, especially after filling up. If you are not getting this then I would concentrate efforts on engine bay and carbs

[wilf]

Oops - wrong thread

[Edmason]

Well I've been looking for leaks in the boot as that's where I thought the smell was coming from, so I changed the washers on the banjos yesterday. However this morning it wouldn't fire, and I realised that the fuel pump was ticking frantically. When I got out to investigate I found a pool of petrol on the garage floor, flooding over the exhaust from the short connector hose at the base of the bulkhead. Lucky it didn't fire up, - literally!
So, a new length of 8mm fuel hose solved the problem for now. I think there's a similar connection at the back so I'll check that tomorrow. What was that you said Julian?
Cheers all.

[ColinFesterBesterTester]

Unless its definitely in the boot, worth also checking the plug at the bottom of each carburettor. I've just replaced the O-rings in mine as one was dribbling fuel. On one of the carbs the O-ring just crumbled upon removal and I realise now that it had been seeping fuel for a long time, creating a petrol smell whenever the engine had run.

[jbuckl]

Well I've been looking for leaks in the boot as that's where I thought the smell was coming from, so I changed the washers on the banjos yesterday. However this morning it wouldn't fire, and I realised that the fuel pump was ticking frantically. When I got out to investigate I found a pool of petrol on the garage floor, flooding over the exhaust from the short connector hose at the base of the bulkhead. Lucky it didn't fire up, - literally!
So, a new length of 8mm fuel hose solved the problem for now. I think there's a similar connection at the back so I'll check that tomorrow. What was that you said Julian?
Cheers all.

I tried replacing as much as possible with nylon.
The nylon can be warmed and pushed onto the pump banjos…. As per original.