Fuel filling problem.................?

Dutchman · Jun 23, 2004

Has anyone else experienced difficulty filling the fuel tank, given that the rubber insert at the bottom of the filler neck (not evident on previous BMW's I've owned) is a nice snug fit around the pump nozzle.

This means the filler nozzle forms a nice seal and doesn't allow the tank to expel air efficiently as it fills with fuel.

This in turn creates a fairly large air pocket at the very top of the assymetrically shaped plastic tank, which I would much rather held fuel.

To my way of thinking there's no point having a petrol tank that allegedly holds 20 litres when you can only ever get 18 litres in.........

So, I decided to mod the filler neck, just as I've done on the previous BMW's I've had......

After removing the shiny bits and stuffing rags down & around the metal filler neck assembly, I drilled three small (3mm) holes near the upper lip (shown in the pic. below) and then reassembled the whole thing.

A quick visit to the petrol station proved the exercise a success in that there was no coughing & spluttering petrol all over the bike and I could actually hear air expelling from the holes.

I also managed to get 21.5 litres of petrol in a tank previously drained to within about half a litre of being dry....

I'd like to think that this may have extended the range to about 230 miles, which is similar to my 1150RT, especially useful where petrol stations are few & far between..........?

Tobers · Jun 23, 2004

I quite fancy doing this. But....

Can you expand on the technique for "removing the shiny bits" please, and clarify what the shiny bits are.

And where did you stuff the rags, and why?

Couldn't you just hold the nozzle so the end doesn't go into the rubber insert?

Ta muchly old chap.

Kave · Jun 23, 2004

Dunno about the shiny bit's.
I guess he stuffs rags in the hole of the tank, so when he drills the small holes, metallic fragments won't go inside the tank. He just pulls the rag up when done and the metal fragments go up with it. Dunno what it would do with the fuel filter.

Dutchman · Jun 23, 2004

Shiny bits........

Okay......

Remove both side panels, via dzus fasteners & plastic quarter turn fastener inside, by forks.

Undo the six filler cap screws (if you open the filler cap & stuff clean rag in you'll stop metal swarf from entering the fuel tank or accidentally dropping a screw in!).....

Then undo two screws near the beak & two which hold the bottom of the the metal panels to the fuel tank and the whole painted tank top & metal side panels come off as one.

I then wrapped another piece of rag under the metal filler neck flange which now has about 2cm movement, restricted by internal plumbing. This rag is again to stop drilling swarf from entering the tank.

Then drill the holes & reassemble.

Clearly this whole exercise is unecessary if you don't mind waiting ages at petrol stations for it to cough & splutter fuel everywhere while you fill it to about 90% of it's capacity..........besides it was pissing down with rain here today & I didn't have anything better to do!!

Tobers · Jun 23, 2004

Excellent - thanks for that. I'm a bit worried about drilling into some important pipe or something. Anyone know if there's any pipes that are in the way?

In the meantime, the rubber neck can be removed by slipping a finger inside the hole (!) down through the rubber bit and then gently prising it upwards. It comes off with ease.

It doesn't solve the air exit problem unfortunately - that will need the hole method, but it should prevent fuel spurting all over the place.

Tobers · Jun 23, 2004

Ah!

Because you can pull the filler neck upwards by 2cm after removing the panels you can see where to drill. Is that correct?

Dutchman · Jun 24, 2004

Tobers said:
Ah!

Because you can pull the filler neck upwards by 2cm after removing the panels you can see where to drill. Is that correct?

You've got it, Tobers.......there is in fact one metal tube which exits at the top of the flange (shown as a hole in the pic) and which has a drain hose attached to the other end, to disperse any overfill......it's easily visible & therefore easy to avoid drilling into................?

As a matter of interest, have you investigated where the overflow pipe exits? On mine the fuel overflow exits right above the hottest part of the exhaust, the 'y' piece just forward of the rear wheel..........needless to say it's now been re-routed.....

Cheers

Dutch

Rupert · Jun 24, 2004

I wonder if this is designed to allow for fuel expansion in hot climates.

If you fill the tank to the brim and it heats up in the sun where can it go but out on the road (via your exhaust pipes!?!)

Rupert.

Keith Chapman · Jun 24, 2004

I assume that this mod would work on the 1150, using the same procedure apart from removing the the side panels and the panels on the tank.

Do you need to wait for the seal on the filler cap to dry and go back to normal size before you replace the six screws?

Dutchman · Jun 24, 2004

Keith Chapman said:
I assume that this mod would work on the 1150, using the same procedure apart from removing the the side panels and the panels on the tank.

Do you need to wait for the seal on the filler cap to dry and go back to normal size before you replace the six screws?

There's no reason why it won't work.......and yes the large 'o' ring seal that fits under the flange will need to dry thoroughly to return to normal size before refitting.

The 1200 has a shaped rubber seal which fitted straight back into place....

Spout · Jun 24, 2004

"Do you need to wait for the seal on the filler cap to dry and go back to normal size before you replace the six screws?"

I recently had problems getting mine to seat. A good smear of petroleum jelly allowed the o ring to slide into place easily (although still oversized).

BJEast · Jun 24, 2004

needless to say it's now been re-routed

Build fault??? Pre-warned I suppose, any dealers watching then please note this for a PDI check!!!!!

B

Quentin · Sep 20, 2004

Hi

Thanks all, this works -- just filled visibly up the neck for the first time.

Cheers

Quentin

PS Drilled only one hole on the RHS of the bike, but slightly larger than the ones you show -- it was the only sharp drill I could find in my toolbox!

After the care I had to take with the swarf on the outer side, I decided to quit whilst I was ahead. I chose the RHS because this is the highest point when filling on the side stand.

finglonga · Sep 20, 2004

Did mine (1150) a few months back used the rags method.

But I also placed an old speaker magnet next to (but not touching) the filler neck base and it caught all the swarf. The rags were used as a safety net .

I just need to remember If I fill up to the brim I must do at least 20 miles before stopping the bike as fuel spills out of the overflow pipe.

:beerjug:

SQD8R · Apr 12, 2005

I've been thinking about this for a while and I think 've figured out why I get better mileage without this mod.

1. I fill up while staying on the bike and I fill it up in a vertical position.
2. I never fully insert the nozzle, I still leave a bit of a gap

I think maintaining this vertical position and the gap from the nozzle might have the same results. What do you think?

GSmonkey · Apr 12, 2005

SQD8R said:
I've been thinking about this for a while and I think 've figured out why I get better mileage without this mod.

1. I fill up while staying on the bike and I fill it up in a vertical position.
2. I never fully insert the nozzle, I still leave a bit of a gap

I think maintaining this vertical position and the gap from the nozzle might have the same results. What do you think?

I've done the mod, fill the same as you and can get over 22ltr in.....I don't think you can do this without.

The mod allows you to fill above the bottom of the filler neck, which otherwise you wouldn't be able to do.

The main reason people do it however is fillup speed.

Schtum · Apr 12, 2005

GSmonkey said:
The mod allows you to fill above the bottom of the filler neck, which otherwise you wouldn't be able to do.

You can. I've filled it level with the cap. It takes a bit of patience but it can be done.

SQD8R · Apr 12, 2005

see I've done that too. Filled ti to the point where it's level with the cap. Are you guys saying that I'm still missing areas, even when vertical, because of venting fuether down?

I'm just confused on how there are air pockets, or whatever you want to call them, from vertical and how I'm not getting all fo the fuel in when I've filled it up to the brim?

JayGee · Apr 12, 2005

As I see it, the mod allows the air to escape cleanly and quickly whilst putting in the fuel. If you fill the last bit slowly with the fuel nozzle clear of the black rubber bit then you can get the same amount of fuel in. If the fuel is up to the top of the black rubber bit then it's completely full. I got nearly 21Litres in yesterday with this technique (but I only had 5 miles to go on the clock thingy). However I might well do the mod soon as refilling would be quicker and easier.

Geriatric Germ · Apr 12, 2005

On my GSA, I seem to remember that I took out the filler neck completely to drill, for safety reasons (petrol doesn't burn but the vapour is highly volatile, and a small spark from the drill, Poof

) and also to prevent the swarf entering the tank as the drill pushes the last cuttings through. But I know nuffink

Fuel filling problem.................?

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