E34 - Running Rich? Fuel Smell when Cold

[cheshiref1]

CAR: 1993 520i 24v M50 (dont know if VANOS or not). Full SH 107,500 miles. (5k miles in 2 1/2 months).

Hi all - newby here, but have been hanging around in the background for a while and used the search tools / posts a few months back to find out info on E34's and subsequently bought a good one!!!

Ever since i have had her, the only niggling problem seems to be the smell of fuel when she is cold. I tend to use her on long motorway runs (what she was bough for!!) and never really notice it, but if i run her locally to the office i notice this problem more...... (PS - have searched, but nothing specific found apart from this very short post!! http://www.bimmer.info/forum/showthread.php?t=27111&highlight=rich)

Basicaly, start the car - all ok - drive as normal. When the temp gets to about 1/4 warm and you stop at lights / junction / in traffic, you get a strong fuel smell. This is the case each time you stop / crawl in traffic until it reaches full temp 1/2 way on gauge and has been there for a minute or two (fully warm). The smell then goes away NEVER to return, until you park her and leave for 30-45 mins to cool back down to 1/4 and you get it again until warm!!! The fuel smell is never evident whilst moving.

I have parked the car up and got out once to see if the smell is coming from the engine bay / rear of car etc. but nothing!! The smell is strongest inside like it is coming through the vents or something.

Car has Full SH and documentation points to new thermostat / coolant back in early October '06 (i bought her 1st week in November). Has also had a new water pump fitted 12 months ago and does not suffer overheating.

Car is PERFECT apart from this - needs some new wheels though as i'm running on original wheel trims and steelies!! Maybe they are antique....

Can anyone help me out??

Many thanks!!! :)

[Tiger]

Pull spark plugs out to see if you have some symptoms first. Otherwise, you will ruin your cat converter if you keep driving.

[Mr G]

I had exactly the same problem, turned out to be the rubber fuel lines on the injector rail...they develop small cracks in them and become brittle over time.

If you pull on them slightly you may see these small tears/cracks in them....or they could even be loose on the rail...pinch the jubilee clips up a tad as well

When the engine is warm the lines become more supple and they dont seep fuel as easily

Cheap and easy fix if its the lines, it seems to be in most cases

[Omega]

Oh yes. Know this one very well. Mr G. has also been there by the looks of things.

Check the U-shaped rubber pipe that comes from the metal fuel pipe into the fuel rail at the front of the engine (on the RHS as you look at the car from the front). It's under the intake manifold. These have a habit of perishing.

Replace the rubber pipe with the BMW part and use good quality jubilee clips. Don't try and be cheap and replace it with a long straight piece that you can bend. I did this (twice) and both times it perished in under 6 months. Genuine BMW part lasted the rest of the 5 years I had the car.

If you are going to ask further/future questions can you please fill out your details in your profile bit. Others won't help you without this.

Are you UK based? Mention this also as it sometimes makes a difference to the location of parts.