I think I might have a fuel leak, how do I find it??
 

I have been out of town for a couple of days, and recently managed to find a single garage to rent for my SC. Yesterday I took a quick trip over to the garage to check up on the car after having been away for a week, and there was a distinct (not heavy, more of a subtle but disturbing) smell of fuel in the garage when I opened the door. I did have a good look at all points that I could think about and could not find any signs of a leak.
As I have never had my SC parked in a single car garage since I got it, I do not know if this is normal or not - I am assuming it is not....

Any advice on how to start investigating and locating a small fuel leak would be greatly appreciated. Is my best form of attack just to replace all soft fuel lines (front and back)??

If you smell gas after storing the car for a week you have a leak somewhere. Be careful, gas vapor is extremely flammable.

You can place clean paper or cardboard underneath the car to determine the location of the leaks.

Find The Leak, yes, but not a fix
 

Cardboard and paper does the trick, but to find the leak fast ... well. Take a Bic lighter under the car and strike it a few times. Ohhhhh, I couldn't resist.

Don't try this at home kidz. Just a joke.

Pursuant to the Idiots Code of Honor I -- and Pelican Parts -- will not be held liable for said opinion/joke and/or its representative haunts and stupidities inherent in said interpretation/implementation forewith the reader(s) finds truth or faleshood in aforementioned opinion.

But if you're gonna do it, videotape it so we can have proof for the next round of Darwin Awards. Cause you baby are gonna be a winner.

That is what I was worried about. I did have a look under the car etc, but could not find any signs of fuel dripping etc. Yet another problem to fix :(

I'm thinking the most likely locations for a leak are:
1. at the fuel pump
2. at the accumulator and filter
3. gas cap (vapor getting out)
4. connections at the tub (front and rear)

My 76 used to give off a faint fuel odor, and when I replaced the gas cap (for CA smog purposes) the smell went away.

Thank you for the recommendations Jon. I know my fuel pump is on its way out - sounds really bad, so I am planning to replace it and all the related soft fuel lines. I am also about to do the annual service, so that will fix the filter - maybe I will have to try to replace the accumulator as well then. I did replace the gas cap recently with a new one - I wonder if that could be the problem??

Your car has plastic lines from the FD to the injectors. I would check the plastic lines. Later cars such as my 82 SC came with steel lines from the FD to the injectors.

Hmmmm, I think the lines to the injectors are quite new. As you can see the engine area is not so dirty :) But I will have a close look, even new parts can have problems!!!
http://forums.pelicanparts.com/uploa...1156012462.jpg

My bet is on the pressure side from fuel pump to the back of the car. The rubber section of the supply line, for example. To inspect this area, the belly cover that goes over the fuel pump and steering rack has to come off. A small leak here will drip into the cover and fuel will evaporate before hitting the ground.

Don't freak out, if you can not find it right away, you may have to run the car to make it come out. Just make sure that if you start or drive it, only do so with a large fire extinguisher at hand.

Keep us posted what the culprit was!

George

Paul did you backdate the heating system on your SC?

Did you modify the airbox to remove the inlet "snout"http://forums.pelicanparts.com/uploa...1156012462.jpg

George, thank you for the good advice. As I have already said I am going to replace the fuel pump up front and the rubber lines at the same time. I will still have to drive the car so I do hope it will still be OK until the winter comes.

Ruf-porsche, yes I did do the heater backdate (http://forums.pelicanparts.com/porsche-911-technical-forum/295291-old-school-heating-best.html). The air box is a replacement open flow unit that I got cheap on ebay :)

Not sure if you want to replace the supply and return lines if they do not leak and the rubber section looks decent. They are going all the way through the tunnel, to meet up with metal lines at the transmission mount. Not a fun job. :(

George

Thank you for the info George. I was not planning to replace any lines within the tunnel. As I understand it is not a fun job. I am hoping it is just a joint that has a leak. Would be nice to have an easy fix for once on this car!!

Also, the fuel level sending unit has a gasket. Good idea to replace this as well. When installing, match the holes up since they are offset slightly. Another thing to check is the gas filler neck. These have been know to rust and have small pin holes.

Good points Jim. I will have a look at these as well...

Pål,

Few more pointers regarding supply and return lines, as I just did this recently ...

Unfortunately, for supply and return, Porsche chose to use hard plastic lines that go through the tunnel and then crimp onto rubber in the front, to clear the steering rack. The rubber section is crimped to the hard plastic and you can only change the entire shebang.

Here a pic from a return line. You can also find them on our host's parts pictures ...

http://forums.pelicanparts.com/uploa...1154497495.jpg

And a picture of the typical (supply line) leak as I had it. This was the last thing I fixed on my SC before I sold it. I think that section being under pressure after you shut off and the 115 degree (F) heat had to do with it.

http://forums.pelicanparts.com/uploa...1156109374.jpg

If it turns out to be one of these lines, post again or hit me with a PM, I can help you with some pointers on how to make it pretty painless.

Keep us posted!

George

Thank you George. I am travelling again this week, so will not get to work on the car again until next weekend. I will PM you when I start to investigate, would be good to have some assistance with this...

Kroggers- Check around the bottom seal of the fuel tank. See if it looks to be wet or deteriated. My fuel tank had two pin holes in it and the gas had the seal completely saturated and smelled horrible. Should be able to see this from underneath. Just my .02.

Thank you Duke, I will look at that as well.