1992 730 - Smell of petrol

Hi all, I'm kinda scratching my head a bit here ...
Yesterday whilst driving I noticed a strong smell of petrol in the car. I immediately stopped and switched off the engine. When I opened the
bonnet there was a pool of petrol in one of the exhaust manifold valleys (between cylinders 5 & 6).
Starting the engine I could see a steady drip of petrol coming from the fuel line that runs just above this point. There is a short length of flexible tubing held on with two jubilee clips and although they didn't appear to be loose I did manage to get one to tighten 1/6th of a turn. The leaking stopped and I soaked up the residue from the manifold.
After a short while the smell went away from the cabin and I thought that was it ... until this morning when the smell came back. This time though I can't see any evidence of a leak, but there is a definite smell of petrol under the bonnet.
Has anyone else come across this, or have any suggestions as to where to start looking?
--
Regards

Steve G
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No,. but you should fix it soon else we will use the past tense when we refer to you. Jim

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Jim wrote: <snip original post>

Thank you for your concern, Jim. Likewise I appreciate a quick fix might be beneficial ... except for the wife who has just upped my life insurance :-))
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Steve G
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That's no reason to be suspicious.
However, if she hands you a box of matches to help you find the leak, then you should be worried.
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Pete wrote:

Yeah, I'd better watch out for her smoking near the car when I'm heads down in the engine bay sniffing for fumes too :-))
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Steve G
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The problem is with old fuel lines. They start to "sweat" petrol, but they look good as new because they the moisture makes them look black. I had exactly the same problem. If you feel them with your fingers you will see that they are moist. Replacing all the fuel lines solved the problem.
Cheers.

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tech27 wrote:

Thanks for the tip. I'll take a look tomorrow :-))
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Steve G
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I had a similar situation develop when the fuel pressure regulator failed on my E30. The fuel pressure more than doubled so any places with marginal sealing started leaking. First it leaked from the hose connecting to the injector manifold. After I tightened that clamp it started leaking from the hose connecting to the filter. After the third leak appeared in two days, I got the message and checked the pressure. Another symtom was that the idle got pretty rough.

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Jack wrote:

Jack,
Funny you should mention the regulator I've been wondering about that. I was trying to decide why it would happen just the once and some sort of temporary blockage (e.g. the regulator stuck shut) seamed a possibility. Also I remember that the idle was a bit rough when I had the leak.
There's an air hose connected to the top of the regulator which disappears down a hole in the inlet manifold casting. I haven't tracked it yet but I guess it connects to the manifold somewhere so that fuel is only circulated when the engine is running.
There is a short flexible fuel hose between the regulator and the solid return pipe which sometimes shows evidence of the fuel inside pulsing and at other times looks like the fuel must be flowing smoothly. Any idea which is correct?
Looks like another job for Saturday afternoon ;-)
Thanks for your help.
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Steve G
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Although petrol is forced through the injectors at moderate pressure - somewhere roughly about 40 psi, the vacuum state of the inlet manifold influences this too by the 'suck' on the injectors. So the regulator is controlled by engine vacuum, and counteracts this effect. So when the engine vacuum is high, like at cruise, the regulator reduces the fuel pressure. At full throttle, the vacuum is at its lowest point, so the regulator is wide open, and the pressure is at maximum.
So the rest position of the regulator is fully open (no vacuum). Any vacuum leak to it (or elsewhere) will tend to produce a rich mixture. A regulator which was stuck open would likely make hot starting and idling impossible or difficult. Fuel consumption would also suffer.
It's a crude but effective system.
--
*I am a nobody, and nobody is perfect; therefore I am perfect*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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When my fuel pressure regulator failed I disassembled it to see what had caused the problem so I would like to offer this clarification on the operation of the fuel pressure regulator. The regulator is downstream of the fuel rail and injectors and the fuel that is allowed to pass it is on it's way back to the tank. So if the regulator valve were to fail open there would be no fuel pressure at all. The rest position of the regulator is fully closed with the return path to the tank closed off by a small metal disk being spring loaded onto the the end of the pipe that is the exit path from the regulator. When fuel is pumped into this chamber the fuel pressure acts on the diaphram that the metal disc is attached to and lifts it off from the exit path allowing fuel to flow through to return to the tank. The manifold vacuum is plumbed to the other side of the pressure diaphram so that the resulting regulated fuel pressure is relative to the manifold pressure instead of relative to atmospheric pressure. My regulator failed because the metal sealing disk became detached from the diaphram so the return path was always blocked regardless of the pressure generated by the pump. It was 20 years old with 300k miles on the car when it failed so this problem should be fairly rare.
London SW

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Not so. You'd simply get the full pressure the pump can deliver.

Think you're wrong. They reduce the pressure in proportion to engine vacuum to compensate for that vacuum sucking fuel out of the injector.
And engine vacuum is high at low throttle openings,so the pressure needs to be reduced. At full throttle you want the designed maximum pressure.

Which will tend to pull the diaphragm down and reduce the pressure?

Most are sealed units anyway, so you just fit a new one.
--


Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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"" wrote: > Hi all, I'm kinda scratching my head a bit here ... > > Yesterday whilst driving I noticed a strong smell of petrol in > the car. > I immediately stopped and switched off the engine. When I > opened the > bonnet there was a pool of petrol in one of the exhaust > manifold valleys > (between cylinders 5 & 6). > > Starting the engine I could see a steady drip of petrol coming > from the > fuel line that runs just above this point. There is a short > length of > flexible tubing held on with two jubilee clips and although > they didn't > appear to be loose I did manage to get one to tighten 1/6th of > a turn. > The leaking stopped and I soaked up the residue from the > manifold. > > After a short while the smell went away from the cabin and I > thought > that was it ... until this morning when the smell came back. > This time > though I can't see any evidence of a leak, but there is a > definite smell > of petrol under the bonnet. > > Has anyone else come across this, or have any suggestions as > to where to > start looking? > > -- > Regards > > Steve G
Hi, total newbie here, not only to the site but to BMWs in general (I just googled "smell of petrol on starting" and this is where I ended up, to be honest). The thing is I am currently test-driving a J-reg 316i for a month - the sellers a neighbour of mine, asking 1500 - and have noticed just the same problem. Do you any of you have any advice to someone who has precious little idea what goes on under the bonnet (the shame of it!) as to whether this is pricey to have sorted at a garage? I defer to your greater wisdom...
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"Nathan_Jo" wrote: > Hi, total newbie here, not only to the site but to BMW's in > general (I just googled "smell of petrol on starting" and this > is where I ended up, to be honest). The thing is I am > currently test-driving a J-reg 316i for a month - the seller's > a neighbour of mine, asking 1500 - and have noticed just the > same problem. Do you any of you have any advice to someone who > has precious little idea what goes on under the bonnet (the > shame of it!) as to whether this is pricey to have sorted at a > garage? I defer to your greater wisdom...
I had a similar problem on a 91 318i, I had it back to the dealers on 2 seperate occasions and they couldnt find anything. I changed the hoses mentioned earlier. In the end a friend of mine found out where it was leaking from, the "o" ring seals on one of the injectors. They are hidden away under the intake manifold on top of the engine. The replacement parts were quite cheap ("o" ring seals) and the job was done by my friend in about 1 hour. I have never smelt fuel since.
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"dandaire" wrote: > I had a similar problem on a 91 318i, I had it back to the > dealers on 2 seperate occasions and they couldn't find > anything. I changed the hose's mentioned earlier. In the end a > friend of mine found out where it was leaking from, the "o" > ring seals on one of the injectors. They are hidden away under > the intake manifold on top of the engine. The replacement > parts were quite cheap ("o" ring seals) and the job was done > by my friend in about 1 hour. I have never smelt fuel since.
Thanks for the tip. Guess Ill look at the fuel lines / regulator / injectors, and if that doesnt work Ill buy another car. Another 3-series that is - hooked on them now...
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Hi.
I am new to this newsgroup.
I've onwed (and still own, amazingly) my first BMW 318i E36 1993 model since 2001.
My car used to also emit the petrol smell. Initially, I was a little worried, as it was quite strong when the car was initially started. Of course, at the same time, my car had damaged rockers, camshaft, and tappets due to infrequent oil changes.
I have recently had the rockers, camshaft, and tappets replaced by my trustworthy mechanic, and now I do not smell any petrol.
I will confess that the annoying tapping noise that could have been considered noise pollution was the primary reason for taking my car in for the repair.
Kind Regards,
-- Jason Tepoorten @HOME snipped-for-privacy@tepoorten.com 8MP Australia

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"" wrote: > Hi. > > I am new to this newsgroup. > > I've onwed (and still own, amazingly) my first BMW 318i E36 > 1993 model since > 2001. > > My car used to also emit the petrol smell. Initially, I was a > little > worried, as it was quite strong when the car was initially > started. Of > course, at the same time, my car had damaged rockers, > camshaft, and tappets > due to infrequent oil changes. > > I have recently had the rockers, camshaft, and tappets > replaced by my > trustworthy mechanic, and now I do not smell any petrol. > > I will confess that the annoying tapping noise that could have > been > considered noise pollution was the primary reason for taking > my car in for > the repair. > > Kind Regards, > > -- > Jason Tepoorten > @HOME > snipped-for-privacy@tepoorten.com > 8MP > Australia >
> > > "dandaire" wrote: > > > I had a similar problem on a 91 318i, I had it back to > the > > > dealers on 2 seperate occasions and they couldn't find > > > anything. I changed the hose's mentioned earlier. In the > end a > > > friend of mine found out where it was leaking from, the > "o" > > > ring seals on one of the injectors. They are hidden away > under > > > the intake manifold on top of the engine. The replacement > > > parts were quite cheap ("o" ring seals) and the job was > done > > > by my friend in about 1 hour. I have never smelt fuel > since. > > > > Thanks for the tip. Guess Ill look at the fuel lines / > regulator / > > injectors, and if that doesnt work Ill buy another car. > Another > > 3-series that is - hooked on them now...
Thanks Jason useful to know. In my case the tapping isnt that loud but the smell of petrol can make my eyes water at times! Pollution of a different kind I guess... Out of interest how much did replacing that lot cost you?
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