Fuel vapour smell in the cabin of 1970 FHC

[Ropariva]

Hi,
We recently had the fuel tank out of the car to straighten the sump and for general refurbishing. The sump filter and all gaskets were renewed along with the fuel filler tube. There was a bit of confusion though when it came time to refit as there seemed to be more tubes than connections to the tank. Also we are not sure which tubes are supposed to go where?
Are there any diagrams available that will assist sorting this out.

Tank breather pipes



tubes




Alternatively does anyone have intimate knowledge of what goes where?

Much appreciated Alan

[MarekH]

These are vapour expansion tank connections.

Page 65 of the tan coloured series 3 Owners Manual has details of the connections and your earlier version is probably similar to this.

kind regards
Marek

[chrisvine]

Alan,

The smaller pipes are the connections to the expansion tank in the rear wheel arch, which has four pipe connections. Three to the petrol tank and the other one vented to the outside (I think it was connected to an emission system on US cars).

I took some garden wire to work out the lengths of the internal pipes in the expansion tank:



This is how I understand it works. When pressure in the main tank builds due to fluctuations in temperature, fuel passes from the fuel tank to the expansion tank. These pipe finish high up in the expansion tank and the fuel falls to the bottom.

When the external temperature falls, the pressure decreases and fuel is drawn from the bottom of the expansion tank via pipe A.

The corresponding connections on the fuel tanks are:



It shouldn't matter which of the long internal pipes is use for the vent to the outside, I just chose the one on the left.

Chris

[Ropariva]

Thanks guys for providing quite a bit of clarity with the tank connections and the excellent explanation of how it all works.
As the expansion tank wasn't removed the three small tubes were still in their relative positions when the tank went back in. I reckon these are connected correctly so have ruled them out as the culprit.
Now the fourth tube.....!??
That remains a mystery.
We know where it comes from and now we know its the vent line, but what we don't know is where it is supposed to go. Below is a picture taken soon after the removal of the tank. The vent tube was just sitting in the bottom passenger side corner and as it didn't seem to go anywhere or have a purpose, that's where it was left when the tank went back in. We are certain its the cause of our vapour smells as its clear this should be venting outside.



As my car has no emissions systems there is no provision for a return tube to the engine bay, nor does there appear to be a hole located anywhere near the tube for external venting.
Chris's series three shown below has a "Y" shaped connector to the external vent behind the wheel well. This seems like a logical way to use the one exit for two purposes. My series 2 doesn't have the "Y" connector or a separate exit, so we are still stumped as to where this is supposed to go.
Surely it hasn't been sitting in the bottom of the tank well for its entire life?



Anyone out there keen to pull the fuel tank out of their 1970 series two in order to answer this question?

[chrisvine]

I think the Y shaped connector highlighted should be connected to the LHS drainage point in channel around the boot lid opening and the overflow drainage outlet in the fuel filler housing.

I'm planning to put the vent for the expansion tank out through the small hole in the boot floor to the right of the fuel tank sump.

Chris