Is there a knack to filling with petrol?

[gibbon]

I have just tried to fill a plus 2 for the first time, I only managed to get around ?15 of petrol in. I can see the fuel when looking into the filler. The gauge only read to half.

I have since driven roughly 15 miles, i can still see the fuel when looking into the fuel filler.

I didn't particularly fill it slowly, I just filled at full flow until it stopped, as I would my modern car.

Am i doing something wrong or do i have an issue? I am aware these cars have a rather 'interesting' fuel breather system, but I can't smell any fuel, am I still a victim of this?


Many thanks in advance.

[Sea Ranch]

Lovely. Welcome to the club.

Presumably you have a giant air bubble/air lock in the tank. The fuel enters the tank on the side of the tank, about mid-way. In order for fuel to continue filling the tank past the fuel filler pipe, the air above that inlet pipe has to be evacuated. This is (one of) the task(s) of the air breather tubes, one on either side at the top of the tank. If these have been plugged or removed, the air can't escape and fuel cannot rise into the upper half of the tank.

Check them out.

Regards,

Randy

[gibbon]

Thanks.

So would I be right in assuming as the fuel gets used up and the level in the tank falls below the filler level the fuel I see in the filler will drop into the tank as normal and wish slow careful filling I should be able to fill the tank?

[Sea Ranch]

Yeah, sorry, slow computer . ..

The curious thing about your situation/description is that it seems you have NO venting of the upper portion of the tank, because you talk about driving 15 miles and the fuel is STILL up in the fuel filler pipe.

When the venting is installed and breathing freely, the upper half of the tank has to be filled slowly or it will overflow the filler pipe. But it can be filled.

So I would check inside the boot, behind the forward trim panel, to see if the pipes are installed, and then check their outlets, under the car, ahead of the rear wheel wells, for obstructions. I'm scratching my head trying to think of ways to confirm they are fully open without having to remove the tank-end of the hose.

Thoughts, anyone?

Here's the Lotus parts diagram (courtesy of the ever-helpful Ray at RD Enterprizes) . . .

[paul m]

it may be full but have a faulty sender or gauge, mine never reads more than half full even when briming. If you are unfamiliar with your cars little idiosyncrasys just run it for a while and see what happens

[Harvey]

Gibbon,

Note that Randy's posting of Ray's fuel tank diagram shows two different systems for venting the tank. My '71 +2S has the system on the left which does not have vent lines running over the tank like the earlier system. With either system make sure the tank is vented as Sea Ranch suggests. I have struggled over my years of +2 ownership with the awkward filler tube which prevents filling the tank quickly and doesn't allow (in my experience) the tank to be filled completely. In order to avoid spilling gas over the rear fender (wing) while filling the tank I slowly trickle the gas from the nozzle of the pump. However, even by this method I have never been able to fill the tank more than 3/4 full on a calibrated gauge. I think this equates to about 12 US gallons.

My biggest problem with the fuel filler has been sloshing gas over the wing when cornering with a full tank. I have taken several measures to cure this issue but that is another subject not raised by your question.

Lee

[mbell]

On the diagram the left tank is the federal evap tank. The right one is the UK/Europe setup.

There a few common mods to the fuel system breathers. Somewhere on here is a write up I did on the fuel system on the plus 2.

The leak from the filler is normally either bad sealing or filler cap with a breather hole that is not required for the plus 2 system.

[gus]

The tank is not full until it is all the way to the neck. The fuel filler enters partway down the tank, meaning you see fuel in the filler neck when it is far from full. To truly fill it you must back the nozzle out and slow the fuel flow and you will get several gallons more. Newer evap nozzles are a pain, but I have been dealing with that for over 20 years.

[vxah]

Bit late here i know but, if you have not done so i would recommend you do the breather mod where they vent into the filler neck then, fit a new cap and seal with a small vent hole.
If your oe vent hoses have been blocked and you re-do them you might get fed up of the constant smell of fuel...
Specially if you keep it in a garage.
I blocked mine for several years and put up with half a tank rather than the smell.. Modded the system now though! Just got to finish the rest of the rebuild! Body is back on, dash in, most of wiring in..

[bill griffiths]

I have had the problem of spending 10 minutes attempting to get a reasonably full tank for the last 39 years!
And usually I am rewarded with fuel on the rear guard anyway.
I recall once running the breather pipes in a slightly different manner, perhaps crossing them over but I cannot recall exactly the procedure except that it came from a modification perhaps in the workshop manual.
Since my plus 2 is an early model, the modification might have been simply an update.
I recall also reading somewhere of the fitting of an extra breather by welding a pipe in the filler pipe and providing a breather pipe from there.
Having a newly tissue coated and painted body, could some kind person direct me to the source of this idea, and whether it proved successful?

[bill griffiths]

I should add that I have searched the forum. Plenty of information, but no apparent cure without using a jigsaw!

[Robbie693]

Bill,

Is this the one you were thinking of?:

[bill griffiths]

Thanks, Robbie. Exactly what I was after. Given that the two tubes at the top of the tank seem too small to vent air sufficiently from the tank while filling the top half, I am thinking of making them bigger, joining them and then running an even larger diameter pipe from the join to below the petrol cap.
Am yet to design the tube below the cap so the larger pipe can be unscrewed to allow the filler pipe to pass upwards throught the rear guard. Perhaps will fabricate a pipe with a flat of sufficient size and thickness.
And, of course, a smaller pipe from one of the tubes at the top of the tank routed as originally designed, to avoid a partial vacuum while fuel is being withdrawn.
Too much work on the finish of the body to continue getting fuel on it!
Thanks, again.
Regards,
Bill

[john.p.clegg]

Similar to...

one of these helps

which is..

John

[gus]

modern cars have no way to vent quickly and work just fine. I assure you it is not a vent issue, but a tank design issue. Now that most of the old snorkle fuel pumps have been retired, filling it is only a minor nuisance