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MG Midget and Sprite Technical - 1975 Fuel leak

Hi

I now have my midget running thanks to the help that I received from this forum, however I now have a even bigger issue!

The car now runs but leaks quite a lot of fuel onto the exhaust which is obviously not good.

It appears to be coming from something that looks like a swirl pot in front of the carburettors. If it helps I can post a picture tomorrow.

Any thoughts gratefully received

Rylan
R Williams

Do you mean the float bowls next to the carburettors?

If it is leaking from the base of these items then the sealing rings need changing but if it is from the top (overflow) then the needles need to be changed Not the needles in the float bowls are different to the needles in the carb.

A photo would confirm
Robert (Bob) Midget Turbo

Picture included sorry about the poor quality, as I only had my mobile on me at the time.

Im sure they are the float bowls but confirmation would be useful, I have put a circle to indicate where I am on about.

The strange thing is that only one of them leaks, the other seems ok.

Rylan

R Williams

yes that's one of the float bowls, as Bob said. If leaking from the overflow on top then probably the needle valve has a bit of dirt stuck in it preventing a clean seating and seal. That would explain one is OK & the other leaks. Undo the 3 retaining screws, remove the float and needle carefully, clean out the fuel and anything else in the bowl - often get a pile of silt and sometimes a hard residue in the bottom. OK to scrape *carefully* with a small screwdriver, and clean out with rag or Q-tips.
David Smith

Thanks for the quick replies everyone with great advice

Thanks David for the detailed instructions, just what I needed! Hopefully this will solve the issue and there will be no more fuel leaks!

Then I can start on some of the other things
R Williams

I mean no offence but looking at that air filter I assume(?) your at the start with your car or servicing so (as always) I recommend

buying a owners Handbook - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html

doing a full and proper 36,000 mile service and maintence

driving as regularly as you can to improve the car and your ownership and enjoyment

oh, and by my experience IF you have to replace the carb bowl needle and seat then consider used if you know of any
Nigel Atkins

Hi Nigel

Your assumptions are correct, I am at the start with the car as I only purchased it in the last week or so.

I plan on doing a proper service in the next week or so, anything you would particularly recommend me doing?
R Williams

Rylan
If you want to try a quick fix tap the float bowl with a srew driver handle when the engine is running, this can sometimes do the job and sometimes it doesnt, worth a try though.
Rob Newt

Yes I can Rylan and I honestly mean it and believing especially as the car is new to you (and you to Spridgets or a long time away from them)

Buy a owners Handbook and do a full and complete 36,000* miles service it shows in the Handbook

That and keeping up regular servicing and maintainence along with regularly driving the car will help no end with you actually driving and enjoying the car rather than messing about with it when you don't want to

Always have a digital camera and notebook to hand and use BEFORE you start dismantling things (not that I always remember - do as I say, not as I do)
Nigel Atkins

Hi again

I cleaned out the float bowl and the silt in the bottom which has resulted in it still leaking from the top but not as badly.

The large orange float was visible, is the needle inside?, if so how do I open the float?
R Williams

Remove the pi tha retains the float to the top of the bowl

this can be done with needle nose pliers

once removed, the needle can be removed as it sits above the float in a chamber of its own.

then you can get to cleaning it or replacing as required.

then dare i say it, rebuild is the reverse of disassembly.
PeterJMoore

Rylan,

Just to clarify Peter's comment I have attached a photo from the Burlen / SU website which unfortunately has some parts with the same reference number!

From your photo it appears you have HS type carbs as expected. The pivot pin I have shown as A, the needle valve and seat as B and the float as C.

The point of the needle valve should be smooth without any ridge where it sits in the seat. If worn, I recommend you change it [for both carbs].

HTH

Doug Plumb

Thanks for that Doug it was rather helpful

I could not get the pivot pin to come out no matter what I tried. Any idea's or is there something I've missed?
R Williams

From memory, the pin can / should only be pulled out from one side as it has a 'ridge' on it to secure it in the lug. Try gently pulling from one side, if it doent move try the other side. Alternatively, gently tap the end of the pin whilst supporting the lug. Again if it doesnt move, tap the other end. A bit of WD40 on it might also be useful.

HTH
Doug Plumb

Quick update

I managed to get the float off and have a clean up, petrol is no longer gushing out (which is good!)

There is however still a very small leak, merely a very small dribble, obviously I would prefer to get it stopped completely, would replacing the float chamber gasket stop this completely?

If not, any other suggestions?

Thanks for the help and knowledge so far everyone, I really appreciate it!

Rylan
R Williams

Here i was thinking
"Fuel leak since 1975?!
there can't be that much left"

;)
Onno Könemann

Yes you should replace the float chamber gasket, buy a few spare

parts (B) 19 in diagram needle valve and seat may need cleaning and where they sit in the head

then fit new gasket and see how it goes

or they may need replacing and you should replace on both carbs - but - I found when I replaced both carbs with new needles and seats that I still had to replace the leaking side with second hand needle and seat to solve the problem, but that's just how things go for me

let us know how you get on - I may have a s/h needle and seat but try sets of first they're not dear
Nigel Atkins

This thread was discussed between 02/03/2011 and 20/03/2011

MG Midget and Sprite Technical index

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