Erling G-P

Car's been smelling of gasoline around the hind quarters for a while. Noticed the other day, that the fuel tank had traces of something running down on the sides, and some wet areas on the bottom too. Took a pic today after arriving home:



Does this look familiar to anyone and/or does anyone know of likely culprits for fuel leaks in this area ?

Spoke to the mechanic at my regular workshop today and he might be able to look at it sometime next week. He would naturally perfer the tank as empty as possible, and of course it's almost full now, so looks like I'll have to drive it although I'm somewhat uncomfortable about the situation.

Anyway, input and suggestions will be very much appreciated.

Cheers,
Erling

Bob in Socal

this will expose fuel filter and pump this is where the leak is
DO NOT Drive this ( gas/electrical) until you fix it.

soontobered84

My leak showed up like yours, but it was from the vent hose that goes between the two sides of the top of the tank. The tank basically wraps around the "frame" and Porsche had to vent between the two to allow proper filling of the tank. Mine only showed up when full. YMMV.

Dennis Wilson

The leak could be the fuel pump plumbing, a bad seal at the sending unit on top of the tank, a broken/cracked vent line (runs from back of fill tube into the bumper then back into the tank) or a cracked/leaking tank. If it leaks all the time, it wouldn't be the sending unit seal or vent tube as these are higher up on the tank.

Again, don't risk driving it until it's sorted out.

Dennis

Erling G-P

Thanks for the replies guys.

Bob, the two 10mm nuts you mention; are they readily accessible without removing something else and/or lifting the car ?

Cheers,
Erling

85fortheDrive

Erling:

First of all, do me a favor and sweep those dried leaves out from under there...!

I'm not sure where the fuel pump is located on a 91. On my 84, it is located under the shroud shown in your picture. In other models, it is in the right rear wheel well. As long as your fuel pump is under that shroud and the shroud does not contribute to the support of the tank, you should have no issue investigating this area first.

Otherwise, the next thing I would do is syphon your tank into holding container(s). I had to replace the tank on my 84 and believe me, if you do need to start undoing support harnesses, you want as little weight in the tank as possible. Easy enough to get the gas back in. The tank is a strange shape (featuring a sort of gooseneck to the point at which you fill gas in it) and can be challenging to maneuver.

If it turns out to be a nick in the tank itself, then I'll be happy to provide removal help if you need it. I had no luck trying to seal mine with an epoxy, but found a replacement on eBay.

Good luck!
Tim

Erling G-P

Tim, thanks for the reply and good wishes.

Don't worry; the leaves have been given their notice - in fact they've been chased out several times this winter, but they seem to move back in again the moment I turn my back...

Fuel is a problem, as I have absolutely nowhere to put 70+ litres of it. Would be a legal pain too, as I believe it's way above the legal limit of how much you're allowed to store at home here (20 litres I think).

Hope I can get the cover off and spot something that way.

Cheers,
Erling

ajmarton

I think I have a leak from the vent hoses as my tank leaks when I fill up. How do I get to the vent hoses? I have an 81 928 5 speed.

Dennis Wilson

If it is the vent hose leaking, the only way to access it is by dropping the tank. I would check the seal at the fuel sending first.

Dennis

soontobered84

AJ-
Disconnect the battery. Remove the fuel pump cover which is held on by 2 nuts on the fuel tank strap. Disconnect the fuel pump and fuel filter from the tank and from the car. The fuel tank will hold a lot of fuel at the bottom of the tank. Have several large containers available to catch the gas when you disconnect the fuel pump. When it stops leaking, there are 4 bolts that hold the fuel tank straps to the body of the car. There is also a bolt at the filler neck that will need to be removed. Remove all the fuel lines and vent lines you have access to. The last vent line is the one between the two sides of the tank and you probably won't be able to loosen it until the tank drops down a little. It is a large vent hose that goes through the fram/subframe. You have to get at least one side loosened/off to be able to push the tank down and out of the car. That large vent hose is what was leaking on my car. YMMV. IMHO this is the best time to clean out your tank/tank filter etc.
Reassembly is reverse of the disassembly.
Good Luck.

Note: Make sure and do this in an area with lots of ventilation.

Erling G-P

Got this fixed this week.

Was a copper gasket according to the mechanic, so a relatively easy fix without need to drop the fuel tank.

Cheers,
Erling