Petrol Smell

[alanrichey]

It's taken over a year but I am getting closer to tracking down the reason for the petrol smell on my Superspec. I had figured out it occurs ONLY after the car has been sitting for more than a couple of weeks. If I drive her regularly it doesn't smell. So coming back from Xmas from a 6-week holiday was an ideal opportunity to do some tests.

 

I exposed as much of the fuel lines as I could to try and see where it occurred. There was no smell initially so I turned on the ignition to let the fuel pump pressurise the system. Still no smell after about 10 minutes. So I started the engine, still no smell after a couple of minutes. So out for a 4 minute 'round the block'. The smell started after about a minute and by the time I got back it was quite strong (and is still there an hour later).

 

Using my trusty nose I could find no smell around the fuel injectors or in the boot around the senders, or at the back of the tunnel. But there was a strong smell coming from the front of the tunnel under the dashboard. So I guess the smell is emanating from somewhere between the dashboard and the fuel filter (about a foot of pipe), but feeling all around the pipe I can find no trace of any wetness.

 

So I'm a bit flummoxed. All I can think of so far is that I have a minute leak (or the pipe has gone porous) and that over a period of weeks fuel is pooling somewhere underneath that area. And then it smells once the car is moving and disturbs it, but eventually disappears when the hot engine has evaporated it. But again, I can see no area where this might be happening.

 

The fuel filter is buried at the back of the engine and incredibly difficult to access so I would like to avoid changing the pipe unless I know for certain that is the problem.

 

Anyone any bright ideas ?

[fry61]

Is it possible to get some very clean/white tissue or kitchen towel under the pipe to see if smell/stain is transferred? if no hint of transfer would leave well alone. We have a petrol smell in Florin's boot if left shut for days/weeks but have never traced any sign of leakage.

[Guest Gargoil]

If the system is pressurised and still no smell.I would be looking at the unpressurised side, before the fuel gets to the fuel pump. I had a leak a few months back but it was easy to trace, the fuel filter had become detached. Like I said, that was an easy one................

I still get a smell of petrol if Betty is stood for any length of time, but that goes as soon as she starts.

What about ignition on so fuel pump on and throttle wide open (don't start the engine), any vapours then?

Edited January 12, 2015 by Gargoil

[alanrichey]

Your under bonnet air is being pushed through the tunnel too - so is it possible the smell/leak is under bonnet but you are smelling it behind dash/tunnel in the high pressure area?

I actually had the bonnet removed when I did the run to try and avoid that. And tracing the smell was done while stationary in the garage and it was defiantly coming up from the gearbox area and not the engine bay. So I suspect not.

[alanrichey]

If the system is pressurised and still no smell.I would be looking at the unpressurised side, before the fuel gets to the fuel pump.

Does that apply in my case ? There are 2 fuel pipes from the pump to the filter, out and return. So isn't the whole system pressurised ?

 

What about ignition on so fuel pump on and throttle wide open (don't start the engine), any vapours then?

I'll test that next time I have let her sit for a bit (might be quite soon looking at this weather )

[alanrichey]

Is it possible to get some very clean/white tissue or kitchen towel under the pipe to see if smell/stain is transferred?

Good thought, I'll try that.

[Guest mower man]

Hi Alan is the pipework the black braided stuff ?it does go porus and smells but hard to find an actual leak , modern fuels containing ethanol also bu--er it up so changing is really the only route mick

[steve in stockport]

Any rubber pipe in your system need to be at least R9 rated to withstand the latest unleaded fuel with all it's additives, otherwise it will degrade and allow fumes without showing an actual leak. I had the braided black hose from swirlpot to high pressure pump and it stank, because of the size I had to swap it for 100% bioethanol resistant hose at £20 metre.

[alanrichey]

I have the usual red and yellow fuel lines (I assume they are safe) from the tank. The extra black pipe connects to the red (feed) pipe just level with the dashboard and goes abut 12" to the filter. The yellow (return) one continues on to the pressure regulator (I don't think there is an additional black pipe, difficult to see). But if the black feed pipe was leaking/porous it wouldn't explain the symptoms, i.e the smell only starts after driving the car for a minute or so after a layup then goes away after a couple of runs.

 

Having read the Haynes manual it tells me the yellow return line is used only if the pressure regulator on the injection rail senses a pressure of more than 1 bar. So I am thinking the return line only starts to get used after you accelerate the car leaving the house. So I wonder if there is some sort of seal/gasket associated with the return line that dries out during a layup so starts to leak when it is first used, but then gets damp, swells, and stops the leak after a couple of runs.

 

Think I will have to get the car up on axle stands and try and access the filter from underneath and check the return line.

[Al Milton]

Hi Al,

I have just renewed my fuel hoses. Like you, I had a wiff of petrol, admittedly constantly in the garage, so with no obvious leak (pressurised or unpressurised), I could only guess at porous hose.

Because I had the same hose at either end of the system, rather than try to track down the guilty section, I replaced the whole lot.

 

8mm id ethanol proof hose from CBS, £12/metre, ordered before 4pm, delivered next day : http://www.carbuildersolutions.com/uk/ethanol-proof-fuel-hose-8mm-516 It's also pressure rated.

 

I don't have a whiff of petrol in the garage now.

 

Hope this helps

Al

[alanrichey]

OK, thanks to all the advice on the forum I think I have convinced myself of the reason for the smell. Following the original post I found the garage had a very strong smell of petrol a couple of hours after I parked up, but this morning there was no smell at all, or any marks on the paper towel I used as per Bob's suggestion, and when I took her for a 20 mile run there was no smell at all. The design of the fuel feed is

and the previous owner tells me he replaced the braided hose between the filter and the injector a couple of years ago as it had gone rotten. So, as many of you suggested, this all points to the second piece of braided hose going 'off'. Although it is OK for normal use, if the car is left stationary for any length of time that hose must absorb petrol. Nothing shows during starting, but when the engine reaches working temperature (a couple of minutes into a run) it will start to evaporate the petrol and the smell will be localised to the front of the tunnel. Once the car is stopped in the garage it will continue to 'cook', so the petrol smell will remain strong for a couple of hours. But by the next morning all the absorbed petrol will have evaporated so no more smell.

 

So in the short term, based on the difficulty of replacing the fuel line in a standard Rover engined Superspec. I will live with it, in the full knowledge that a blast around the block and leaving it in the garage overnight will solve the problem. However, I will take Al's advice and buy a metre of cable for when I can fix it.

 

Thanks to everyone for their input and I hope other people with the same problem find the thread useful.

[fry61]

& don't light your garage with candles in the mean time!!

[stevedohc2b]

I would fix this ASAP we had a french member who's garage burnt out from a fuel leak problem and lost car. Think he had a heating boiler in the garage. I am sure that a local garage could replace for you if not able to access your self.

 

Stephen

[alanrichey]

I've got the new pipe in the post so will definitely take a look soon. Although at this stage I don't have any trace of a leak, just a slightly porous line, so I reckon I have some time yet

[Guest chrispine]

The fuel pipes on my Superspec come up the top of the transmission tunnel, above the chassis rails under the cover between the seats, the original rubber pipes disintegrated and gave lots of problems with the carb, the pipes were covered in shiny metal braid so looked nice, when I went to injection I put a swirlpot in the boot, drilled through the front/bottom part of the boot and ran the new pipes straight through instead of underneath the boot, quite easy to do. Also used to have a very strong smell of petrol when cornering on right hand bends/roundabouts, that was fuel coming out the top of the sender unit, removed it, drained the tank and scraped out the many bits of rubber (used a fish slice), sealed the sender gasket with Black Bob, no petrol smell and now far more to the gallon.

 

Chris