Fuel mystery

[yatisr]

This morning I started my car (a 323I affectionately known as The Elephant) in preparation for my usual Monday morning 65km trip to work in Kuala Lumpur. I pulled out of the garage and noticed fresh fuel on the garage floor. Upon further inspection, I noticed fuel dripping in the vicinity of the right fuel tank. I suspected a leaking hose. I immediately decided that caution was the the better side of valour and parked the old girl in the garage and rode the train to work. Later in the morning, my uncle jacked the Elephant up and inspected the fuel tanks. He noticed fresh fuel stains around the right tank. However, when he started her up, there was no leaking fuel. He took her for a drive and there was no fuel leak. He left her idling in the garage for twenty minutes; again no fuel leak. Does anyone have any idea what may be wrong?

Some facts that may be pertinent:
(a) I drove the car down from Kuala Lumpur on Friday morning. The journey was about 65kms long. Average speed was 110 kmh. Nothing unusual was detected. At the end of the journey, there was no discernible smell of fuel from the area of the fuel tanks;
(b) The car remained unused until Monday morning. I did not start her up between Friday morning and Monday morning. When I started her on Monday morning, she fired up on the first crank;
(c) The fuel gauge was reading close to full, but with about 80km on the trip meter, the tanks could not have been full. (As is my habit, the trip meter is set to zero each time the tanks are filled up. The last fill up was on Thursday. Hence, upon my return home on Friday, the car had covered about 80kms since her last fuel up);
(d) On the weekend, I was examining the Bowden (accelerator) cable and pressed the accelerator a couple of times to check the movement of the cable. The engine was off when I did this;
(e) My mechanic inspected the fuel tanks last Thursday while attending to the air conditioning and could not find any leaks. He is puzzled that I claim that I noticed a leak this (Monday) morning;
(f) The fuel system is the standard Bosch K-Jetronic system. The entire fuel system is as one would expect on a right hand drive (UK specification) car.

Any ideas? Thanks for helping.
Yatis

[Jeroen]

Quite likely to be a burst hose on top of the tank, see the FAQ section on the fuel system viewtopic.php?f=38&t=18255

[yatisr]

Thanks Jeroen. My Uncle checked the car repeatedly yesterday (Monday) and could not detect any damaged hoses. He said that the hoses looked new. This morning (Tuesday), he drove the car up from Seremban (where my Mum lives and where I go home to on the weekends) to my apartment in Kuala Lumpur. This is a journey of about 75 kms. He stopped three times along the way. No leaks were detected. I then took over the car from him and drove her to my office this morning, a journey of about 13 kms. Again, no leaks. I checked with my mechanic yesterday too. He was adamant that the fuel hoses are relatively new. They were checked at the start of the year when there was in fact a leak. The leaking hose in that instance was replaced. The other hoses were fine.

My guess is that the pressure in the fairly full tank caused some fuel to escape through the vent hose as I started the car early on Monday morning after a weekend of inactivity. In any event, I shall have the fuel lines checked once again as you advise.
Thanks.
Yatis

[Jeroen]

It must have come from somewhere and usually you see traces on top of the tank if you remove the cover under the rear seat. Another culprit with a full tank can be the rubber seal between the fuel pick up unit (that goes into the tank) and the tank, that's in the same location.

Normally excess fuel or fuel pressure is led to the vent tank on top of the right rear wheel well, it doesn't just get to poor straight out of the tank, only if there's a leak somewhere. I always take fuel leaks very, very seriously. Imagine what will happen if it gets just a little bit closer to the exhaust...

[yatisr]

I agree that a fuel leak must be ruled out by a proper inspection before any other theories are entertained.

[uwbuurman]

Since the problemen seems to be dissapeard, I think that exces fuel has leaked out. So I'm pretty sure it will happen again after filling her up again. So to find the leak, I suggest filling the tank will petrol, carefully, litre by litre.

Tank it selve is still alright? No rotten seams?