Unable to completely fill fuel tank

[B_land]

Since owning my Elan I have never been able to fill the fuel tank completely the nozzle clicks at 3/4 full. I tend to fill to 1/2 tank anyway but it would be useful to completely fill the tank for those longe journeys. I suspect there is a fault with the vapour canister are these regularly available and easy to change or is it a specialist. Grateful for your ideas?

[Simon_P]

I presume that you mean that the gauge reads 3/4 when the pump clicks. That would suggest that the gauge is incorrect. How far do you drive between 3/4 and half?

The vapour cannister is available but has nothing to do with how full you can fill the tank

[B_land]

Thanks Simon - i don’t think the tank is full when the nozzle clicks as after filling the needle drops steadily from the 3/4 mark during driving. If it was full it would remain for sometime at the 3/4 mark? My first thought was that there is a fault with the vapour system where it is not allowing the air in tank to be released when filling.

[John_W]

How many miles do you get to a tank? I get about 290 from full to warning light on, which equates to about 29 mpg.
If I want, I can fill my tank to overflowing just by not stuffing the filling nozzle all the way in. I can’t see any reason (apart from a leak) why you wouldn’t be able to fill the tank.

[Brit-Car-Nut]

My Guess: The float could be cracked (fuel gets inside it so it doesn't "float" as high).

This could cause a 3/4 reading instead of full (when the tank is really full) and when it shows empty, you could still have around 1/4 tank still available - the float is on the bottom of the tank but because it is "heavy" so you are getting a false reading and there is still petrol available.

Not so common cause: The "resistor winding" in the sender could be damaged and stops at the 3/4 point on the sender, but you would still be able to fill the tank completely if you ran the fuel level toward the bottom of the tank. It would just stay on 3/4 longer than normal (until it gets past the damaged winding).

The tank can hold 10.2 Imperial Gallons (12.3 US Gallons). How much can you add when it shows "empty"?

How long can you drive after the gauge shows "empty"?

Carry a can of petrol as you get close to the gauge reading empty and see how long you can go before having to add more fuel.
Or-
Open the fuel tank and LOOK at the float and manually operate the sender to see what readings you get as you raise and lower the float.

REMEMBER, The fuel pump will operate for a few moments when you turn on the key, so make sure you put a hose on the outlet nipple and route the petrol safely into a container.

[HJ2]

I'm with John and I vote for a leaky float as well.
They are cheap as crisps and if you can open the fuel tank on top, replacement is pretty straight foreward.
I had the same problem and it was cured with a new float.

[lotusflasherman]

Thanks Simon - i don’t think the tank is full when the nozzle clicks as after filling the needle drops steadily from the 3/4 mark during driving. If it was full it would remain for sometime at the 3/4 mark? My first thought was that there is a fault with the vapour system where it is not allowing the air in tank to be released when filling.

Withdraw the nozzle to the end of the filler pipe and carry on filling carefully. When you can see petrol at the bottom of the filling tube you can consider the tank 'Full'. Then check the Fuel Gauge. You may just have to alter your filling technique... some pumps click 'Off' when I first start filling an empty tank if I push the nozzle too far in.

[Fredjohn]

I can only fill my tank to the very top (level visible in the filler pipe) if I remove nozzle slightly and fill gently, not "full throttle".

To be honest this applies to virtually every car I have owned. The auto shut-off of the pump can be overcome with slow careful filling.

No point in spending loads of time and effort in checking the float if the tank really isn't full.

Take simple solutions first, then the expensive one after!

[HJ2]

True!
After that: opening is for free and a float is just a couple of quid!

[lotusflasherman]

True!
After that: opening is for free and a float is just a couple of quid!

but if it ain't broke don't fix it...

[Rambo]

Thanks Simon - i don’t think the tank is full when the nozzle clicks as after filling the needle drops steadily from the 3/4 mark during driving. If it was full it would remain for sometime at the 3/4 mark? My first thought was that there is a fault with the vapour system where it is not allowing the air in tank to be released when filling.

Withdraw the nozzle to the end of the filler pipe and carry on filling carefully. When you can see petrol at the bottom of the filling tube you can consider the tank 'Full'. Then check the Fuel Gauge. You may just have to alter your filling technique... some pumps click 'Off' when I first start filling an empty tank if I push the nozzle too far in.

I've never found that pushing the nozzle too far in when you start is beneficial to either party

[John_W]

[HJ2]