mysterious fuel leak

[sklbase]

Hello, just looking for ideas. I have an 1989 325i that underwent an s54 swap at a local shop. Everything with the swap is working great except there is one issue - a fuel leak that is very small. The shop installed a full cell in the trunk to avoid starvation issues with tracking, and after the car sits for any amount of time, there is a fuel smell in the main compartment, but mainly the trunk. The shop had it for another two weeks after the swap was completed and thought they tracked it down, but the smell is still there. It does not smell when driving.

I knew that they had changed most of the fittings, so I tried and experiment - I wrapped all of the lines in the trunk with plastic wrap - not straight saran wrap, but that sticky stuff that will stick to your plates, and then ran the car and left it on for a couple of hours. I did not find any condensation, but when I took it off, four out of the five reeked of gasoline. Is it possible that all of the lines are bad? They are brand new, but maybe it came from a bad spool?

I am going to repeat the experiment this week with a control - some plastic wrap in the trunk that is not wrapped around a line and see if there is a distinct difference.

Thanks for any help.

[7pilot]

I would strongly recommend that you take it back to whoever designed/built the fuel system.

I'm trying to teach you to suck eggs. Raw fuel does not burn. Fuel vapour is explosive.
They have provided you with a dangerous product.

m

[sklbase]

mysterious fuel leak

I understand it's a problem, and dangerous. The question I am really asking is - is it possible all of the lines are seeping fuel vapors?

And don't worry, it will be going back there soon.


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[gearheadE30]

The only way that fuel lines would be seeping vapor is if the fittings are loose or if it's not actually fuel line. Anything rated for use with fuel should not have an issue.

Is the tank externally vented, either to a charcoal canister or to somewhere on the outside of the car? If it isn't vented, then you'll build pressure in the tank as it sits and you will probably get some of that smell from vapor pushing past seal interfaces. If it is vented into the trunk, it will have the same effect. All that vapor has to go somewhere, since gasoline is volatile and has a fairly high vapor pressure.

[Supratreo]

Find out what they used for the lines. If they have any rubber connections with the incorrect hose then it could sweat and cause that issue. Also, what did they run for a vent/EVAP system? Could be the system is pressurizing and letting the vapors go past the gas cap or something.

[Supratreo]

I read all of the posts except the very last one haha.