Fuel Filler Tubes

[Mike’S-a-loon]

Hello folks,

Winston (now residing in Portland, Oregon) has been suffering a petrol smell inside for a while now.

I previously noticed some petrol around one of the rubber connectors that join the filler inlet to the tank via a section of metal tubing, and ordered a new pair from Wadhams.

Today I finally found some time and pulled the whole lot out (not the tank), and was surprised so find a second corrugated tube running inside the outer tube.

This runs from the filler nozzle down into the tank. The outer shrouds are also fully exposed to fuel at both the filler and tank ends.

So, here’s my question: what is the point of this inner tube? It doesn’t seal at either end, the cavity around it is open at both ends, so what is the point of it? Is there any reason I can’t just delete it?

Attachments:

[enigmas]

Hi Mike, the outer tube is there in all probabilty to vent air out of the tank as fuel enters from the inner liner. Fuel entering a closed container displaces the air within. Tanks with poor venting (whilst fueling up) usually and to use an Aussie term, will "spew" fuel out of the filler neck as the tank reaches it's full status. The air is still trying to evacuate from the tank so an inevitable push and shove occurs with the result that both fuel and air gush out of the filler neck.

I hope that explanation suffices.

Nil desperandum. 😎👍

PS. As Winston was fully repainted, the filler cap would have been removed and replaced, possibly without a sealing gasket or perhaps with the original gasket but in poor condition. This area also needs to be sealed as any gaps between the filler cap mounting and the body may allow fuel vapour to enter the boot space.

[dmaxwell]

I had the same question when I went to replace the rubber filler hoses (from the tank to the metal elbow and from the metal elbow to the body fitting). I removed it altogether and have had no problems. The elbow below the filler spout has always caused the gas to foam as you fill the tank, meaning that it takes FOREVER to fill the tank! I think it is due to the sharp bend, rather than a more gradual bend that would help the gas flow easier to the tank, just my opinion!

David
California

[Mike’S-a-loon]

Winston has always had in issue with fuel spurting out as the tank fills. 

I think I will leave the inner hose out and see what happens. If it gets worse, it's a very quick job to refit it.

[enigmas]

Another option you could try is to increase the size of the air vent holes.

The inner "hose" fueling portion of the petrol filler system should also (I believe) extend into the tank only "slightly" (perhaps 1" or 25mm) beyond where air is trying to exit at the tank end of the filler tube. As the tank is being filled with petrol, air is also rushing out; so there should be no conflict/interaction between fuel entering and air exiting the tank.

[lagain]

May 16, 2023 4:37:13 GMT Mike’S-a-loon said:

Winston has always had in issue with fuel spurting out as the tank fills. 

I think I will leave the inner hose out and see what happens. If it gets worse, it's a very quick job to refit it.

One of the few faults with the P5 is filling the fuel tank, due to curves in the pipe.
If you can find a garage with a sloping forecourt, where the car leans away from the pump it will fill easier.
Before there were pumps with automatic cut off it was a nightmare.

[Mike’S-a-loon]

May 16, 2023 9:34:53 GMT lagain said:

May 16, 2023 4:37:13 GMT Mike’S-a-loon said:

Winston has always had in issue with fuel spurting out as the tank fills. 

I think I will leave the inner hose out and see what happens. If it gets worse, it's a very quick job to refit it.

One of the few faults with the P5 is filling the fuel tank, due to curves in the pipe.
If you can find a garage with a sloping forecourt, where the car leans away from the pump it will fill easier.
Before there were pumps with automatic cut off it was a nightmare.

This is really good to know, thank you! I have always assumed this was a quirk of my particular car.


I guess I will refit the internal tube after all, as it was probably the original engineers best effort to mitigate the issue.

[Mike’S-a-loon]

Actually, I wonder if the original tube being corrugated is part of the problem, and creates turbulence. I will see if I can find a smooth sided option…