Finally got my A14 running right in the 120y coupe when i notice a small wet patch on the ground at the rear drivers side. I could smell straight away it was fuel. After some testing it seems only to leak when electric fuel pump is on. I thought this would mean a simple leak from the connector hoses to and from the pump but they seem to be fine. I checked the top of all the breather hoses and filler and they seem fine so i am completely stumped. Anyone got any ideas? I just simply cant work out how it can only leak when the pump is on yet not be either line to or from the pump? The fuel is seeping out right at the back of the drivers side chassis rail near where the back of the leaf spring bolts on.

Cheers
Trav

Return line set up? No connected right?
Make sure they are all good hoses too some weep through under pressure I have found. Pin holes or tiny nicks in them

Ok so replaced hose to and from fuel pump itself. Still leaking. Replaced fuel return hose from fuel return rail to a T piece above tank next to filler(see below). Still leaking. Stumped again.

Does anyone know if a aussie 74 120y coupe had a standard return line? The reason i ask is mine has the return rail that ends before the tank. It then has a hose from the return rail up to a brass t piece next to the filler in the boot. One side of the t goes back into the top of the tank. The other side seems to run up into the breather system above the filler. Does this sound right? Im thinking this could be an aftermarket return setup that was done when the a14 turbo setup was built. It was using a lot more fuel and pressure with the turbo but now i have converted back to carby im thinking maybe the excess fuel is flowing through the breather system due to the T piece just being plumbed into what would normally be a simple breather? This is a complete guess though? Any thoughts?

Thanks
Trav

They just plumbed it Into the filler vent. Not stock.

I need pics. I re purposed a tank vent as a return 2nd top one so the top one will still vent fuel vapor on a hot day.

Sure the pumps not leaking?

Yeah im positive the pumps not leaking. I just simply cannot find the leak. Ive been trying all night. There just simply is no leak in any line to or from pump or return that i can find. The fuel is seeping out of a really funny spot at the rear end of chassis rail as i said. How in the hell can it get in there? Its a fair old leak too. I had the pump running for about 3-4 mins and there was a wet patch on the driveway about 20cm in diameter. I used a very small rubber hose, wrapped it in tissue paper and stuck it all over the top of the fuel tank from every angle i could and it was bone dry. Im completely baffled.

Is there any way do you think it could be a split in the tank itself? I dont think so because it only leaks when the pump is on. Surely then it can only be in the lines that have fuel pumped through them by the pump itself?

I will try and get some pics up tomorrow and show you what i mean.

Trav

I would remove the plastic panel from inside the coupe and see if its leaking at the filler.

I took a video this morning but haven’t been able to upload it to youtube due to WiFi connection being down at work. So I have just taken a screenshot and will explain it for now. I will try and get the video up tonight when I get home.

1. This is the line from the fuel tank into the pump which has been replaced and is not leaking.
2. This is the line from the pump to the fuel rail that runs up to the engine bay. This has also been replaced and is not leaking.
3. The return line is a rail back from the engine bay and stops just after the diff. There is then this hose that joins to the brass T piece at 3.
4. This line leads into the top of the tank. This hasn’t been replaced as I would need to drop the whole fuel tank to get to it but there is enough room to get my fingers in there and I cannot feel any leak where the hose connects to the top of the tank. I have also used tissue paper wrapped around a small hose and stuck it all around the connection into the tank and it is bone dry.
5. This line is the top of the breather line where they have tapped the return line in. I was thinking maybe there is too much pressure and fuel volume in the return line and I am getting fuel push up into this line and through the breather system. I checked for leaks right through the breather system and couldn’t find any and therefore if excess fuel was running through it, I would assume it would just flow back into the filler or back into the tank via the other breather pipe (red hose at the top).

The arrow is pointing to where the leak is exiting from under the car. As i said at the rear end of the chassis rail just behind where the leaf spring attaches. The video later will show this better.

One last thing I am going to try tonight is to remove the T piece and simply connect hoses 3 and 4 together so that the excess fuel will just run straight into the tank. This will eliminate or confirm any theory of excess fuel in the breather system.

Thanks
Trav

Attach file:

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  2015-06-10-08-01-513.jpg (142.49 KB)

If you save the photo as a JPEG you can get a 800x600 or maybe a 1024x768 to upload. The PNG type it is now takes up too much file space. As it is it is too small to tell much.

Definitely not a stock setup. It looks like some hoses are cut too.

So 3 ts back into 4 and 5?
You need at least one vent tube at the highest point to vent vapors.

With the t peices too you need to ensure the 90 degree t is the one you don't want direct feeding Into. So I would re orientate the t so it flows from 3 straight into 4 with the branch to 5.

Looking closer I think it's pushing fuel up the 5 line and it's leaking out possibly where it joins fuel filler. Is your large fuel filler tube split near the clamp?