Hi All,

Thought I'd ask a for a few ideas before I get up to my elbows in petrol... On the weekend (after doing about 200km after filling up both the tanks) the fuel gauge was showing empty. The LHS tank was nearly completely empty (checked with a dipstick) and the RHS was nearly full.

After leaving it for a couple of hours at the Minikingdom show it levelled out slightly, and then I filled up on the way home and the LHS tank took 14L and the RHS tank took 6L. The breathers all look OK, my thought is possibly the pickup on the bottom of the RHS tank is getting blocked. Any other ideas?

This afternoon after sitting for 24 hours the tanks are level.

Cheers, Tim

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1970 MK2 Cooper S

Breather pipe blocked. Stick a 1.5mm drill into it at top of tank and twiddle with your fingers.
Happened to mine, same symptoms. [edit] It got blocked when I cleaned out the RH tank and used rust converter in it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks guys

All the pipes and hoses in the boot are less than 12 months old.

I’ll double check the breather is clear tomorrow

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Well the breather on the top of the tank was a bit restricted with dirt but not blocked. I opened it up with a drill bit as suggested.

The pickup in the bottom of the tank looks pretty clear


I’ll see if that helps, if not I’ll check out the fuel lines

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They should level out reasonably quickly. I often only fill one tank and though I’ve never timed it I’d say it levels out within 5-10mins.

Do you have the metal interconnect pipe or just rubber hose? Dodgy hose perhaps??


Sent from my iPhone using Tapatalk

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

It's got the metal link pipe and short connecting pieces similar to what the factory used.

I would imagine during normal driving each tank would be drained evenly, there wouldn't be a preference for either tank. There also shouldn't be a problem with vented/non-vented fuel caps if the tanks are vented. It's strange I only noticed it now after 6 months + of the extra tank being installed.

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Hi Tim, I had the same problem and it turned out the breather for second tank was blocked.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

If the tank filter was blocked, how on earth would you clean/ remove it?

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Stick a drill up it.
But on LH one you may be able to reach it through the fuel gauge sender hole.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Simple test.
Take both fuel caps off and see if fuel level equalises quickly.
If it does then the interconnecting pipe, tank filters and hoses are OK.
Problem is with breather tubes or tank caps.
Just remember the tank vent pipes need to go to the opposite side of the car and should be attached to the underside of the parcel shelf and exit through the boot floor.

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

If you want to de-rust your tanks, I used this stuff on my XJ6 and it works like a charm:

http://www.kbs-coatings.com.au/product/rustblast/

Drying the insides quickly using heat gun/compressed air/hot sunshine will avoid any flash rust recurring.

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Thanks all for the help

I filled the car up yesterday and noticed they still weren't even. This afternoon I removed the breather line from the top of the RHS and couldn't blow through it. There was a bit of a kink in the breather, but it's all sorted now!

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