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I am hunting down the source of gas fumes in my trunk.  I have replaced all of the cloth-covered hoses with new rubber hoses, replaced the gasket on the pump supply unit, and replaced the filler neck and gasket. 

 

 

image.thumb.png.3dcfd5ce5b10b6549bcb4724c6e83f54.png

 

Obviously the fuel sending unit is all goobered up, but I do not find a reference to the #5 gasket in the OEM catalog.

 

image.png.05c5fa9c35cc1370749adac7105f5aa3.png

 

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What is normally used there?

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(edited)

Since BMW used two different types of tii pickup tubes, there are two different seals.  #5 is the sealing ring (o ring shape) for the twist in style tube.  Ring is BMW # 16-12-1-105-332

 

 

 

 

 #3 is the flat rubber seal with pre-punched holes for the bolt-in style.

Edited by jgerock
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Your sender unit is not a Tii one, its a carb car unit with a fuel pickup tube. Is that old tube suitably goobered to stop fuel spilling out??

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@Swiss 2002TiiI've been fighting with an intermittent fuel smell in my trunk as well.  As a veteran of odor elimination, I have done ALL the standard tests and parts replacement.

 

Here are some tips:

-  confirm that the 6mm bolts are not leaking from the threads.  An old pickup gasket will allow fuel to seep up the threads, especially with a full tank.  The gasket will split around the holes because of over-torquing of the bolts.  Lately I used some blue loctite on the thread to seal them as well.

 

I bought a new pickup gasket from W&N and found it to be too soft.  It easily split when I torqued the bolts.  So I visited a local gasket manufacturer and bought a sheet of fuel-rated (Nytril I think) neoprene in 3mm thickness.  It's beefy and firm. I had fun creating my own gasket.  Now I have no leakage around the bolts.

PickupGasket1.jpg.a33197a4935aeef8172f18503fc3774c.jpg

 

 

-  I think you need another sender unit.  A tii sender unit and a new o-ring.  That will eliminate the possibility of the sender leaking.  A cool DIY tool for removing and replacing the unit: a butchered PVC plumbing pipe cap.

SenderWrench1.jpg.0ab93508d6bbca359e49e0ca809c5066.jpgSenderWrench2.jpg.792a236708fd0e1ae0ad05e80a0eefdb.jpg

Makes it Sooo easy to remove and replace the sender.

 

Having said all that, I still have a minor smell of "old" fuel in my trunk.  Not raw gasoline, but "dirty rag" type of smell.  Still  trying to determine where it is coming from.  I'm leaning toward the breather system in the tii - from the aircleaner to the catch-can to the filler neck.  I still haven't tested to see if there is a plugged plastic pipe or crimped hose in the long path from the engine to the filler neck.

 

Good luck and get yourself a new sender unit. ☺️

 

 

 

 

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Thanks All,  W&N currently does not show the sending unit, but I will check with Paul W. at Maximillian.  I've been assembling a care package of bits and bobs (drain valves, fuel barbs and tees, etc.) with my sister in NC, so I may add to that package.

Actually, I don't see the sending unit in the drawing, only the suction tube.  Does anybody have that number handy?

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Check Rogerstii.  They have a European Tii sending unit shown under Fuel System.  Pretty pricey.

Good luck in your obtaining one.

Glen

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(edited)

Holy Moley those things are expensive!  I think I'll start by pulling mine and cleaning it up, finding the O ring, etc.

 

I put Vaseline on my bolts when I inserted them into the suction unit, but thinking about gas splashing around, that would be gone in minutes or seconds.  I'll give the blue Locktite a try.

 

The re-purposed PVC cap is a cool tool!

 

That standard 2002 sender in my tank... isn't the Tii tank deeper?  Wouldn't it actually require a longer sending tube?

Edited by Swiss 2002Tii
additional info

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2 hours ago, PaulTWinterton said:

I had fun creating my own gasket. 

So the beige piece on the left is the cardboard template you made from the gasket in the rear, and the new Nytril gasket is on the right?

Boy Paul, you really love makin'  stuff! ? (As do I!)

Knowing how you like your tools, I was looking for the string to create the circle with that X-acto knife, but I'm sure you have a tool for that circle cutter!?

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The rubber O-ring used on the fuel pickup/sender (carbureted cars) and sender only (tii's) is made from some sort of synthetic rubber that swells when exposed to gas.  Old tech tips books warn against getting an appropriately sized O-ring from the hardware store or plumbing supply house as they aren't affected  by gas exposure. 

 

A trick I've used when installing a new O-ring is to lube it with silicone grease to make it easier to reinstall the sender without bunching up the O-ring as you turn the sender to lock it in place.  

 

mike

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30 minutes ago, Swiss 2002Tii said:

 

That standard 2002 sender in my tank... isn't the Tii tank deeper?  Wouldn't it actually require a longer sending tube?

 

I think the tii & standard sender are same length....fuel tanks are same capacity.. i have a standard and tii sender here which are the same length...i am assuming that was true for all regions/years

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Yep, researching further, only the Turbo had the larger capacity tank.

Fortunately, this isn't one of those show-stopper urgent issues!

 

Good to know about the special gasket, Mike.

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Not to thread highjack but I'm dealing with the same gas smell in the trunk also.

I was told I have a tii tank in my carbureted 73.  The fuel pick up gasket is NLA if I read correctly.

Option suggestions ? I'm I making one if possible.

 

IMG_3026.thumb.JPG.6e576d6502a913b874a68db7ec2afa0a.JPG

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42 minutes ago, jp5Touring said:

Not to thread highjack but I'm dealing with the same gas smell in the trunk also.

I was told I have a tii tank in my carbureted 73.  The fuel pick up gasket is NLA if I read correctly.

Option suggestions ? I'm I making one if possible.

 

IMG_3026.thumb.JPG.6e576d6502a913b874a68db7ec2afa0a.JPG

I had the sealing ring special ordered from BMW for my twist in pickup tube.

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For the sender, I think it is the same as the O Ring for the fuel pumps and senders for the E30.

 

16-12-1-150-391

 

As far as the non-Tii nipple, I have used a "Plasti-Dip" vacuum fitment with no leakage for oh, 200,000 miles.

 

Check the vent tube where it exits the trunk just below the license plate. The rubber fitting may be a conical stopper with a slit cut in it. Sometimes it comes loose or the fumes can come in from the slit. An alternative is a grommet with the same consequences. Do you have a plastic vent tube or the old metal part? Check for nicks or cracks in the plastic vent.

 

In very rare occurrences, the seam of the tank can rust through and have weeping leakage there.

 

Check the return fuel line where it attaches to the pick-up. Do you need that plastic piece for a larger fuel hose?

 

 

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3 hours ago, Swiss 2002Tii said:

I was looking for the string to create the circle with that X-acto knife, but I'm sure you have a tool for that circle cutter!?

 

Not really.  Just used the compass to draw circles on the cardboard and protractor to mark the degrees for the bolt holes.  Hole punch for the cardboard bolt holes.  Leather punch for the rubber bolt holes (tight holes for 4mm shanks).  X-acto to cut cardboard by hand.  Shears to cut rubber by hand.  Nothing fancy.  

 

You want fancy?  Talk to @conkitchen  Cardboard Magician.

 

 

3 hours ago, Swiss 2002Tii said:

I think I'll start by pulling mine and cleaning it up, finding the O ring, etc.

 

That should work fine.  A proper "fuel rated" seal on the end of the fuel line fitting is also critical.

 

3 hours ago, mike said:

Old tech tips books warn against getting an appropriately sized O-ring from the hardware store or plumbing supply house as they aren't affected  by gas exposure. 

 

It seems to me that back a few years all generic o-rings were for plumbing.  Now you see more "fuel rated" descriptions on bins at ACE, for example. 

 

I made sure that I bought the proper "neoprene/rubber/whatever" from a gasket supplier, which we fortunately have in our neighborhood.  Most of their business is fuel-related.

 

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