Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Petrol tank fuel return block

  1. #1
    Active Lancista
    Join Date
    Nov 2013
    Location
    Nottingham
    Posts
    24
    Downloads
    39
    Uploads
    0

    Petrol tank fuel return block

    I have a S2 with blockage in the fuel tank return. The blockage is inside the tank and I have tried wire coat-hanger and compressed air but its not working.
    does anyone know what the design is inside the tank is their a pip in their or filter ?

    My garage reconnected the return to the main fuel line (using a t connector)which works but isn't right and it doesn't allow the air to escape.

    Paul

  2. #2
    Legendary Lancista lancialulu's Avatar
    Join Date
    Sep 2007
    Location
    Colchester
    Posts
    2,159
    Downloads
    55
    Uploads
    0

    Re: Petrol tank fuel return block

    Weird. No filter only on main feed. S1 cars did not have a return so you could run like that with the return blocked off but care with fuel pump ressure if you have changed to electric. I would be more inclined to get the return clear. I have not done an autopsy on a tank so dont know the structure of the return pipe but it must be simple I would have thought even for Lancia. With the fuel tank cap off can you not air line the pipe??

  3. #3
    Master Lancista Fen Fulvia's Avatar
    Join Date
    Aug 2013
    Location
    Huntingdon
    Posts
    189
    Downloads
    41
    Uploads
    3
    Blog Entries
    282

    Re: Petrol tank fuel return block

    Hiya,

    I've had a look at the tank I have in the attic, and the return pipe follows the feed pipe down towards the bottom of the tank.

    First photo is taken from the filler pipe and shows the feed pipe, the return is hidden behind it. The next photo is taken from the fuel filter holder, and you can see both pipes. The return is on the right, and fits outside the fuel filter. It's possible that the return is just full of gunk from the bottom of the tank, as it's outside the filter..

    hope it helps!

    Fen Fulvia.



    Attached Thumbnails Attached Thumbnails 0.jpg   1.jpg  

  4. #4
    Active Lancista
    Join Date
    Nov 2013
    Location
    Nottingham
    Posts
    24
    Downloads
    39
    Uploads
    0

    Re: Petrol tank fuel return block

    Hi
    Thanks for taking the time to look, this explains why the coat-hanger didn't work its probably to rigid to get round the bend.

    I will try a softer wire, failing that I think its take the tank out and give it a good clean out.

    Thanks again.


    Quote Originally Posted by Fen Fulvia View Post
    Hiya,

    I've had a look at the tank I have in the attic, and the return pipe follows the feed pipe down towards the bottom of the tank.

    First photo is taken from the filler pipe and shows the feed pipe, the return is hidden behind it. The next photo is taken from the fuel filter holder, and you can see both pipes. The return is on the right, and fits outside the fuel filter. It's possible that the return is just full of gunk from the bottom of the tank, as it's outside the filter..

    hope it helps!

    Fen Fulvia.




  5. #5
    Legendary Lancista lancialulu's Avatar
    Join Date
    Sep 2007
    Location
    Colchester
    Posts
    2,159
    Downloads
    55
    Uploads
    0

    Re: Petrol tank fuel return block

    You can get an idea of the gunge by undoing the drain plug. Also you may see the filter around the inlet has disintegrated over time so make a new one. If the tank has not started to rust internally gunge should imho be minimal.

    When i did mine a few years ago the plug was very tight but worse was it just came out 1/2 inch and jammed due to the filter housing (I did not know the structure of the filter at the time) had come apart and sprung open causing the remaining petrol to spray out sideways. Heart stopping moment but luckily no naked flames about at the time....

  6. #6
    Active Lancista
    Join Date
    Nov 2013
    Location
    Nottingham
    Posts
    24
    Downloads
    39
    Uploads
    0

    Re: Petrol tank fuel return block

    I wasn't aware their was a filter in there, thanks for the heads-up.


    Quote Originally Posted by lancialulu View Post
    You can get an idea of the gunge by undoing the drain plug. Also you may see the filter around the inlet has disintegrated over time so make a new one. If the tank has not started to rust internally gunge should imho be minimal.

    When i did mine a few years ago the plug was very tight but worse was it just came out 1/2 inch and jammed due to the filter housing (I did not know the structure of the filter at the time) had come apart and sprung open causing the remaining petrol to spray out sideways. Heart stopping moment but luckily no naked flames about at the time....

  7. #7
    Master Lancista Fen Fulvia's Avatar
    Join Date
    Aug 2013
    Location
    Huntingdon
    Posts
    189
    Downloads
    41
    Uploads
    3
    Blog Entries
    282

    Re: Petrol tank fuel return block


  8. #8
    New Lancista
    Join Date
    Nov 2017
    Location
    London
    Age
    58
    Posts
    1
    Downloads
    1
    Uploads
    0

    Re: Petrol tank fuel return block

    thanks for all the tips here. This forum is a Godsend.

    Postscript on unblocking the fuel return pipe, as I had the same issue on my berlina. The car ran dry when I was tuning it and I left it overnight. Had blocked fuel pipe and fuel return pipe as a consequence - I think of solidifying sludge. The car hasn't been on the road for 10 years or so.

    The fuel pipe was easy to clear using a bicycle pump to push (and a brake-bleeding negative pressure pump to pull petrol through) leading to a satisfying bubbling sound in the tank. The return pipe less easy. I got the main pipe along the body clear using the pump but the steel pipe in the tank was blocked and no amount of pressure (well, up to 100psi) would shift it. So I tried the 'rodding' approach.

    a)coat hanger - as mentioned above too thick
    b)thin garden wire - too bendy
    c) thick garden wire - got stuck at the bend
    d) welding wire - did the job!

    The engine of course then refused to start. So much investigation of fuel pump, filters, jets (one was blocked -more deployment of bicycle pump) etc. Then in desperation I pulled the plugs out which where wet but fouled after all the crud and rich running. Result, a start!

  9. #9
    Experienced Lancista carcrank's Avatar
    Join Date
    Jan 2017
    Location
    Rokeby, Victoria, Australia
    Posts
    54
    Downloads
    23
    Uploads
    0

    Re: Petrol tank fuel return block

    It there some sort of pressure relief valve in the carburettor that then vents to the return line?

  10. #10
    Legendary Lancista Marnix's Avatar
    Join Date
    Aug 2011
    Location
    Belgium
    Posts
    1,167
    Downloads
    59
    Uploads
    8

    Re: Petrol tank fuel return block

    Nope, no valve in the carbs. On the rear carb, there is connection piece that passes fuel to the rear car (and trough the connection on the carb passes also fuel on to the front carb). The fuel feed is connected to the 8mm tube connection. The fuel return line is connected to the smaller 6mm tube of the connection piece. It is worth knowing that at the inner end of the smaller connection tube, there is a 1mm (approx) diameter restriction. This is to ensure that there will be fuel pressure on the carbs, and not ALL the fuel will just be pumped trough the fuel return line back to the tank. So it is not a pressure relief valve, but just a restriction with a tiny opening.

    It is possible that this restriction is blocked by dirt that has been going to the rear carb. It is fairly easy to take the connection piece off, and have it checked and if necessary cleaned. Inside the connection piece is a brass mesh fuel filter.

    If there is dirt in the carbs, it may be necessary to proceed with a more extensive cleaning out of the fule system (pump, carbs). I always fit a disposable plastic fuel filter between the endpoint of the copper pipe line coming from the tank and the fuel pump (there are delicate valves in the fuel pump too that need protecting against dirt).
    Lancia Fulvia 2C 1964
    Lancia Fulvia Coupe Rallye 1,3 1968
    Porsche 924 1979
    Alfa Romeo 33 1.4IE 1993

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •