Those tanks will grow due to water absorption. SOME people have had success with emptying the tank completely and letting it air dry for a week or two. Unfortunately, it will never go back to its normal shape or size. YAY for ethanol.

 

I agree, same problem numerous times, got the front bolt in, then enlisted the aid of my ( construction working) stepson, together we literally 'squeezed' the Tank, to align...just.....the rear bolts

Don't blame the Bike, as much as the Ethanol loving fuel barons........Ducati amongst others are having exactly the same problems.....and their Bikes came at a 'premium' even amongst Triumphs!!!!!!!

 

I've posted in other threads about my misshapen plastic tank. I only took it off a couple of days to fix the damn fuel gauge and then it wouldn't go back.

I put in the front bolt, with difficulty, and then have the back bolts in place with home fashioned rubber grommets holding the tank. Maybe your tank has stretched too much for that.

 

BruceG,

You might try setting the tank out in the sun for a while and getting it nice and warm, then (with a helper) muscle the tank back into position.

Make sure you vent the tank before you start fighting with it, as it may 'balloon' a bit when heated.

As stated above, this isn't a Triumph-specific problem. Compared to the Ducati's, it's only an annoyance. Several Ducks have required new tanks. My 'local' dealer has rows of bad tanks in his shop, replaced under warranty.

 

I just pulled my tank two days ago to replace those cheap plastic fuel couplings, and since I'm waiting to get the replacement parts I left the tank off. I just ran out and throw it back on just to play it safe and it seemed to line up with everything and went in, but I was scared for a minute. I hope you get your tank back on sooner than later. I really love my Sprint but little things keep popping up that remind me more and more of my 83 VW GTI that I used to own. I think besides that just having parts more readily available are my two biggest grips about Triumph.

 

I think besides that just having parts more readily available are my two biggest grips about Triumph.

Triumph parts availability in the UK is superb. Order before 3.30pm and with the dealer next morning, even for my 20 yr old Trophy 900. Sadly, something goes very wrong with the system in the US.
Try Lings (http://www.worldoftriumph.com/section.php/4276/1/triumph_parts). I undersdtand they ship worldwide next day and are often cheaper than buying locally even allowing for postage.

 

I just reinstalled mine by myself, put the front bolt in but not tight. Then I checked the rear grommets and tried to feel if one wall is thinner than the other, every little bit helps.

Removed my battery and used a 2 x 4 for leverage. 2 x 4 is about 3 ft long and place one end down into the battery box and leveraged on the rear of the tank.

Good luck, its a pain.

ps - check front and rear of tank for grinding on frame welds. I dremel tooled off some big burrs from the frame welding.

 

Contracting Plastic Fuel Tank



Empty the tank of fuel, place in a deep freezer for 30min, this should 'shrink' the tank and allow the three bolts to line up with the threaded holes.

 

Does this work?

Empty the tank of fuel, place in a deep freezer for 30min, this should 'shrink' the tank and allow the three bolts to line up with the threaded holes.

I've got the same problem with a 2002 ST tank that won't go back on the bike. I'm about to try this method after I clear out the freezer.

I'll post results when I get done trying it.

 

Hi everyone. I've just registered to resurrect this old thread, say thanks to kapton for the battery box tip above and give a hand to any other poor unfortunates like me who end up here via Google.

I was doing some repairs, took the bolt out of the back of the tank and then ran the engine for ten minutes, because I'm an idiot. The heat made the tank change shape and it was misaligned by 1/4". Enough that there was no way the bolt was going back in.

Struggled for ages and eventually did this, bracing some short lengths of wood diagonally against the frame and then tapping them straight with a hammer until the tank was pushed forwards enough. Worked for me! It took a bit of teasing to line up but got there in the end.

 

It's not actually the heat from the engine that causes it to elongate. It's the water/ethanol content of the fuel that gets absorbed into the nylon the tanks made of so it expands and distorts. Once you unbolt it the tank goes 'ahh' and then you can't get it back on.

 

This has been an issue since the bikres were new, but it is interesting to note that aprilias have the same tank material but do not suffer as badly. The sprint 08 onwards has a steel tank, which rusts badly.
The only solution for the incoming biofuels, is to use stainless steel (316 grade) tanks, but no one here makes them, only India seems to produce them for Enfields.

 

The sprint 08 onwards has a steel tank, which rusts badly.

Curious why you say that. My 09 is rust free and I've seen plenty other Sprints of similar age with no rust issues on the tank.

I could see it being an issue (not just with Triumph) if there was water in fuel tank and it was allowed to sit for a long time but bikes that are used frequently with regular fuel top ups are not likely to have the problem.

 

Wot I did

I had the fuel tank problem (as you might guess from my signature) from some years ago - thought I was losing my marbles at first as I hadn't heard about the phenomenon... "I'm sure it fitted here like this before!?"

This is what I have done over a couple years to deal with it FWIW:

• Trimmed the front nose of the tank and sculpted the underside of the nose a little so it can move about 1cm further forward towards the headstock
• Trimmed a bit off the backside too though that was more about getting it to fit against a new battery. BE CAREFUL not to go too far if you do this as the fuel reaches some way into the partly hollow mounting lugs.
• Drilled and tapped a new front mounting hole into the frame about 1 cm in front of the original
• Trimmed a bit off the front underside of the lower front rubber to allow it to sit flat on the slight slope to the headstock
• Eventually had to fit bar risers as bar ends were hitting the ballooning tank on full lock (not enough room for fingers and almost certainly an MOT test fail in the UK)
• To try and prevent further worsening of the problem I lined the tank with Flowliner Armourcote epoxy treatment. Before applying the epoxy, not having a huge empty freezer to play with, I left the tank to air for a week with the pump panel off then filled it with A3 molecular sieve dessicant and sealed it up (with plywood and polythene) again to assist in extracting moisture from the plastic (not sure if this really did anything much, and it was a bit of a dusty pig to throughly clean out of the nooks and crannies afterwards - but belt and braces).
• (Whilst I was at it I drilled out and removed corroded water drain nipple and epoxied a larger diameter plastic pipe fitting (it still gets some corrosion blockage though a bit further up the pipe though 😫))

The last part of this saga (epoxy lining) was about 2 years ago and the tank size has remained stable so far and doesn't require use of hydraulic rams etc to put it back on, so cautious optimism.