Fuel Tanks Pre & Post Facelift

Post Mon Dec 09, 2013 9:37 am

Will a facelift fuel tank fit a pre-faceluft car? Need a 325 tank for my 316 chromie.

Thanks

Post Mon Dec 09, 2013 9:43 am

It's 55 and 62 litre tanks rather than pre and post facelift. The smaller tank was still used in lesser models right up to the end of production.
Tank will fit, but needs matching fuel pump and fuel gauge, plus changes to the plumbing and wiring.

Post Mon Dec 09, 2013 9:45 am

That was quick!!! Thanks.

Post Tue Feb 25, 2014 1:46 pm

Got what looks to be a 63l tank. Have another quick question.

My old tank only had one sender. Whilst I got another loom with this larger tank from a 325i, it's not the correct one (seller did tell me this so no problems there). The loom is for a single sender also, but has the correct plug for the fuel pump which my old one didn't.

I know I need to connect the 2 senders in series, but do I need to connect in a certain way? Is there a positive and a negative on the sender unit, or does it really not matter?

Post Tue Feb 25, 2014 2:04 pm

Connect it any way from what I remember, just break into the wire on the LHD side of the rear seat area for the extra sender

Post Tue Feb 25, 2014 2:18 pm

Great - Thats what I thought.

I was just going to cut the existing sender plug (it has the wrong connections anyway), and take one of the wires to right terminal on sender 1, the other wire to left terminal on sender 2, the run a new wire between the 2 remaining terminals on each sender.

Bloody difficult to explain but easy to do !!!!!!

Post Tue Feb 25, 2014 2:23 pm

Only thing that has a positive and a negative is the pump. Senders need to be connected in series, but it doesn't matter which way.
You will need a matching fuel gauge though. Fuel low level light will be accurate, but the gauge will read empty when you have half a tank left.

Fuel return hose has to connect to the side of the new tank, not the pump assembly as on your existing tank. Without the hose connected there, the LH side of the tank won't be used.

Post Tue Feb 25, 2014 2:25 pm

Brianmoooore wrote:Only thing that has a positive and a negative is the pump. Senders need to be connected in series, but it doesn't matter which way.
You will need a matching fuel gauge though. Fuel low level light will be accurate, but the gauge will read empty when you have half a tank left.

That was going to be my next question as I thought I'd read that somewhere in the wiki. Assume I need a gauge from a 325?

Post Tue Feb 25, 2014 2:32 pm

Any touring or 320/325 saloon. I've added a bit to my last post since you quoted it.

Post Tue Feb 25, 2014 2:44 pm

Yep, got it. I need to run a new fuel return line as the car wasn't previously fuel injection, just carb.

I'm wondering whether to put the fuel filter in the normal location next to the fuel tank or in the engine bay (it was previously in the engine bay with the 316 M10 engine). Any down-sides to it being in the bay? (Its a new 325i filter)

Was also going to use 3/16 brake-line pipe which I assume is similar or the same as fuel pipe. It's the nickel kunifer stuff. Will I get away with 3/16 for the return or does it have to be 5/16 /8mm?

Post Tue Feb 25, 2014 8:00 pm

You can buy the complete pre shaped return line from the dealer for under £20, also, make sure you only use hose that has "SUITABLE FOR USE WITH UNLEADED FUEL" printed on it

Post Tue Feb 25, 2014 8:32 pm

DanThe wrote:You can buy the complete pre shaped return line from the dealer for under £20, also, make sure you only use hose that has "SUITABLE FOR USE WITH UNLEADED FUEL" printed on it

Bloody hell!!! Really??? Why am I pissing around trying to make them up. Is that the same for brake pipes? Do they come pre-shaped and flared?

Post Tue Feb 25, 2014 8:45 pm

Yep, brake pipes come in straight lengths though, with brake nuts and flared ends. Problem is steel is a git to bend and just rusts anyway

Kunifer is much better for brake pipe

Post Wed Feb 26, 2014 1:23 pm

Cheers. Will get the petrol pipe ordered.

Noticed the tank is a little furry around the edges. Thinking is I will rub down to metal, then zinc 182 and hammerite black. Is the tank OK to paint?

Post Wed Feb 26, 2014 2:57 pm

Take a long,hard look at the inlet stub,the swines tend to fail there first,closely followed by the top/bottom seam.They are such buggers to replace that it may be easier to fit a pattern replacement whilst you have the thing in bits.

Post Wed Feb 26, 2014 6:49 pm

Prise the seam around the tank apart with a large screwdriver and shake out the dried up seam sealant and rust. The actual weld is about 12mm in, and won't break if the tank is anything like savable.
Wire brush in between the seam as far as possible, treat the remaining rust with phosphoric acid, paint with primer, add seam sealant, then work your way around the tank squeezing the seam back together.
When you refit the tank, make sure that the rubber hose on the inlet stub isn't pushed hard up against the tank, and position the hose clip as close to the end of the hose as is safe.
This eliminates most of the water trap that causes the inlet stub rust problems.

Post Thu Feb 27, 2014 9:04 am

That's some fantastic advice. Thanks to all who have given me help on this topic. Really appreciated