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Spare Fuel Tank For 2002 Roundie


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Hey, I wonder if anyone would be interested in a discussion about spare fuel tanks, an extra capacity fuel tank for the 2002?

 

I used to do lots of cross country driving, Colorado to Maine to Florida to New Mexico to Portland, and Canada as well. I really hated being on the road with 'civilians' or what my wife calls 'The Great Unwashed' due to their unpredictable and dangerous driving habits. So, I used to do most of my traveling at night with the truckers, in my opinion the safest time to travel.  Problem I had was the smallish capacity of the tank, 12.5 gal. is the most I ever got into it.  Since I was out at all hours, I pretty much had to stop when I saw a station open, cause I never knew where the next one was, didn't want to get stranded at 3:00 am... but stopping for 5 or 6 gallons is tedious.

 

SO has anyone else done something to increase fuel capacity of their 02 with a permanently installed tank, or with another style in place of the stock tank, that held more fuel?

 

Yes, this is leading somewhere, since you probably guessed by now.

 

Andy

Edited by MoBrighta
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mlytle - You are correct. According to real oem, the March 1966 to April 1971 cars had 46 liter tanks, the late cars 50 liter tanks and the Turbos had 70 liter tanks. Of course the first two seem to be available but the Turbo tank is not.

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I suspected as much -- the dreaded NLA.  70 liters would be very nice, around 18.5 gallons!

 

I was looking for significantly increased capacity, so I got out my tape measure, climbed into the trunk, and designed another tank entirely.  It fit in the front of the trunk, up against the bulkhead, with less than an inch clearance on top and both sides. It was roughly rectangular, matching both angles of the rear bulkhead and just clearing the rear deck speakers.

 

All penetrations are in the top - fill, vent, supply, and a Stewart Warner 'generic' fuel gauge that was re-wired to match the stock sender's resistance range, full to empty. Plumbed it to a fuel selector solenoid valve, electric fuel pump, and filters of course. Switching the tank also switched the gauge input so I could see fuel level in both tanks.  Both tanks full, range was about 1,000 highway miles.

 

It's quite heavy, made of 14 ga. stainless steel with 3 baffles.  When you open the trunk, the back panel is at the front edge of the trunk opening, so there's still a bunch of trunk space left.

 

It holds about 28 gallons.

 

Anyone interested in pictures? I can pull it out and snap a few.

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The E9 fuel tank is the same shape and is larger. Its available in 70L (18.5 gal) and 72L (19 gal).

Max has them new for $830 - part number for the 72L is 16 11 1 112 233.

Or hit your favorite bone yard.

 

Dont forget you will need the longer sender/pickup to reach all that extra fuel.

 

Bill Riblett put an 02 tank in his E9 when he had issues with it years ago.

 

HTH Beaner7102

 

Try the Link for pictures in an old post (I searched: E9+Fuel+Tank)

 

http://www.bmw2002faq.com/topic/80971-high-capacity-fuel-tank-part-2/?hl=e9%2Bfuel%2Btank#entry397385

Edited by Beaner7102
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Lotsa luck finding a clean E9 tank.  But you could go over the interior with an Eastwood or POR-15 kit and maybe you'll be okay.

 

However, as you've already made your new tank and all... why not plumb the new tank directly into the old to have in effect only one tank, one sender, no switching between tanks.  Yes you'd have to seal the lower tank to the upper in order to make it effectively one, but why not?

 

You now have 50/50 balance F/R....?

Edited by Honolulu
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Lotsa luck finding a clean E9 tank.  But you could go over the interior with an Eastwood or POR-15 kit and maybe you'll be okay.

 

However, as you've already made your new tank and all... why not plumb the new tank directly into the old to have in effect only one tank, one sender, no switching between tanks.  Yes you'd have to seal the lower tank to the upper in order to make it effectively one, but why not?

 

You now have 50/50 balance F/R....?

As I said, the new tank is sitting in the trunk, the original is under the trunk floor. One is totally above the other.

Having one large tank, one supply and vent, and one sender is attractive, but there are other considerations...

 

Two good reasons why they should not be connected - gravity, and penetrations in the bottom of the tank.

 

I did not want even the remotest possibility of fuel leaking around the supply line, or at the weld where it penetrates the tank. You notice that the original fuel tanks have the pickup and vent and sender (and stage 1 pumps on later BMWs) all going in the top of the tank.  There's a good reason for that.  Sure, having one tank drain directly into the other with a single pickup point would be nice in theory, but practical and safety considerations did not suggest that answer. 

 

Here's a third reason: the stock tank's filler cap would be below fuel when the second tank was more than 1/4 full.  It is NOT designed to seal against a head of fuel, so if tied together, fuel would certainly leak past the gasket, don't you think? I mean, spirited driving with a full tank can cause weeping, so steady and significant head pressure might prove disastrous.

 

No, I thought about this long and hard before laying over three hundred clams on the line, and was quite satisfied with the outcome.  Plus what could be easier than flipping a switch under the dash? I was already using an electric fuel pump in the trunk, so adding a $12 fuel selector solenoid valve and a couple feet of fuel line was simple.  I had already re-wired the car for lighting and fuel pump, so there were plenty of wires from the dash to the trunk (I had run extras for things I didn't yet know I was going to need).

 

You mention a 50/50 balance F/R-- I just happens I had the car on load cells after some collision repair, and it did in fact weigh almost exactly the same on all four corners +/- about 28 lbs.  Part of the reason it was so much fun to drive, I guess  :rolleyes:

 

Off topic, kind of --- I also had the battery relocated under the back seat, right side, for three reasons- 1), weight balance and rotational inertia reduction; 2) protection from possible collision damage; and 3) protection from the elements and under-hood environment, like road salt, extreme heat and cold, grease and oil, antifreeze, etc. We built a box and welded it in the floor pan to provide a level mounting location and stay clear of the seat bottom springs. A hard hold-down too, naturally.  Worked out very slick with a mud-flap rubber cushion cut to fit under the battery.

 

I ran a 2-0 welding cable (the kind with a gazillion uber-thin strands of copper) from positive to the starter solenoid, and a nice beefy strap from negative to the body at the seat belt mounting point.  That battery lasted 14 years, through several bone-dead cycles after I left parking lights on accidentally - and I had 14 bulbs lighting in the parking light circuit... I guess that's why I'm the tail light guy.

 

Anyone interested in seeing the tank? 

Edited by MoBrighta
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What would be very interesting is the max depth from the mounting point and max height for the E9 tank.  That way an accurate comparison can be made of fitment.  

 

Tbone can you supply this info?

 

thanks

 

 

Dennis

Edited by zinertia
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Well, since you have offered twice, we should take you up on it. Pictures please.

OK, I got the tank out of it's hiding place, cleaned it up, took some snaps.

 

Dimensions of tank: width 28" (71.2 cm), height 15" (38.2 cm), front to back 16.5" (42 cm) at the bottom, 12" (30.5 cm) at the top.  This maximizes the volume of fuel by using every available cubic inch in the front of the trunk. It was installed with half inch closed cell foam padding below, both sides, and in front.  It was retained forward with a tie-down strap between the wheel houses.

 

Overall height with fittings, 16.75".  As you can see in the side view, the front (at right) fits snugly up against the bulkhead. From my experience it holds 28 gallons.

 

Material, welded stainless steel, 14 gauge.  Three baffles at 1/4 points, running front to back. You can see the welds in some of the pics.

 

Back view is what you see when you open the trunk.

 

Side view shows the front on the right, back on the left.

 

Front view shows the angled face that fits up against the back seat bulkhead, sloping back about 5.5" up.

 

Top view shows the fittings (l-r): sender, vent, fuel pickup, and filler neck.  There's no 'unleaded-only' restrictor in the filler.

 

This is an industrial strength fuel carrier; used for cross country travel so I could go all night without being forced to stop every 150 miles or so to top off (and finding the station closed). This also kept me clear of the amateurs, so I could make better time safely.

 

The 270 mile cruising range on the stock tank was extended to about 970 miles on both tanks.  I also found it handy going to Canada and back, with their much higher fuel cost. Fill up in Detroit, get in and around, and get back without having to pay for gas at $1.45 per liter!

 

I am considering selling it, just in case anyone else has a more rugged but than I do at my 'advanced age.'

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wow, I like this tank! Have thought about pulling the spare tire well out before and making something fit there. Now the question would be how much would you need for it, if you did sell it? Need to go measure the trunk, with the strut brace, not sure if it clears the space in there.

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I was planning to delete my spare tire compartment and current fuel tank next winter and run a big fuel cell. A turbo on the M20 could make it quite thirsty and I plan on going on some big road trips so its only natural. Alpina had a larger tank aswell

 

AlpinA+90L+Fuel+Tank+3+(2).jpg

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With all the idiocy on the road, I'd be afraid that a tank in the spare tire well would be vulnerable to rear end damage, what with these cars being well prior to 5 MPH bumpers and all...

 

Now with upgrades to double tail lights and brighter brake lights that I do, and a third LED brake light that Hella sells (model 38), you have a better chance of survival!

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wow, I like this tank! Have thought about pulling the spare tire well out before and making something fit there. Now the question would be how much would you need for it, if you did sell it? Need to go measure the trunk, with the strut brace, not sure if it clears the space in there.

A strut brace may sit down far enough that is does not clear - I didn't have one, so the only things I had to clear were the trunk lid torsion sprints and the rear deck speakers.

 

Go and measure, trunk floor to bottom of strut brace.  Also measure where the brace sits relative to the bulkhead sheet metal, how far back.  In the extreme case, I suppose you could cut the top off the tank, reweld it at a lower height, it's just stainless - easy to weld.

 

As it sits, I suppose it's worth about $250, ready to install and plumb and fill.  I suppose you first will want to clean the inside, just on GP. 

 

It could be used without connecting the sender if you didn't want to go through that exercise, I mean you know how many milles per gallon you are getting, roughly, right?  And if it was a secondary tank, you still have the stock tank, and can use that when the other ran out.  Or if you want, I'll provide a wiring diagram of how I had it connected, using a DPDT switch under the dash. I had it switch the sender and the solenoid so that it read the fuel level in whichever tank the electric fuel pump was drawing from.  I used a basic 'universal' sender from Stewart Warner, re-wired to match full and empty resistance values of the stock sender (4-70 Ohms if I recall). The fuel selector solenoid I just picked up at an RV parts store.

 

Let me know what kind of clearance you have under the strut brace.

Edited by MoBrighta
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