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How do I get my Austin A40 Mk 1 to stop conking out?!
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LRossi



Joined: 04 Nov 2008
Posts: 2

PostPosted: Tue Nov 04, 2008 8:15 pm    Post subject: How do I get my Austin A40 Mk 1 to stop conking out?! Reply with quote

Hello all, my name is Marco Rossi and I'm currently looking after my son's 1960 Austin A40 Mk 1 while he's at uni. It's a bit of a saga, this one, so I'd make sure you're nice and comfy with a foaming stein or a fortifying cuppa close at hand before getting into this...
Basically, more or less since we bought it a year and a half ago, the car has been plagued by a tendency to splutter to an ignominious halt mid-journey. It flatly refuses to start again either, unless you walk away in despair and leave it for a couple of hours then return, at which point it will usually start again with the first turn of the key then drive off again as sweetly as you like, as though the whole embarrassing and potentially bloody dangerous episode hasn't taken place at all.
Steps taken to alleviate this problem - by a mechanic, I should add, since shamefully neither I nor my son have even the merest scintilla of a clue regarding anything mechanical - have so far included:
(a) the purchase and application of a carburetter service kit;
(b) the replacement of the fuel pump with an electric pump, which you can hear ticking away nicely when you turn the ignition key after the car has conked out... so we know the pump works, at least;
(c) the cleaning out of 48 years' worth of gunk from the fuel tank and fuel lines;
(d) examination of the fuel tank itself, using a mirror, which revealed that the pipe inside it which conveyed the fuel to the engine had come adrift. This was our eureka moment: I had noticed that the car usually seemed to conk out when going uphill, and this seemed to tally with the notion that the pipe would lift out of the petrol at an 'uphill' angle... therefore fuel starvation, therefore conking out. This was rectified, and for a couple of blissful months the car ran as beautifully and unfussily as any car I've ever driven. Then, a couple of weeks ago, it got up to its old tricks again, going up a hill, at 6.40am on my way to work. I came back at lunchtime and it fired up straight away - still facing uphill, of course - so I drove it directly to the garage and got them to drop the tank out and examine it... but the tank was fine. The mechanic then said that he'd heard that Mk1 A40s were prone to having their carburetters freeze on cold mornings; and this did happen on a cold morning, though nowhere near freezing. It did it again a few mornings later, again cold but nowhere near freezing, and this time while driving along on the level. Yesterday, a comparatively warm morning, it conked out again, this time going uphill...
I like to think that I have a reasonably lengthy tether - matron - but I am absolutely swinging off of the end of it now. What on earth is up with that A40? It's not even as though there's anything complicated about them. I'm warming to the theory that the car is in fact haunted.
If anyone can offer any suggestions as to what the trouble might be, I'd be indescribably grateful: and I do apologise for taking up so much of your time if you've managed to read this far...
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47p2



Joined: 24 Nov 2007
Posts: 2002
Location: Glasgow

PostPosted: Tue Nov 04, 2008 8:50 pm    Post subject: Reply with quote

You say you hear the fuel pump ticking away when it conks out, if the pressure was up to the settings you wouldn't hear the pump, so I would be looking at the needle jet in the carb.
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Rick
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Joined: 27 Apr 2005
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Location: North-west UK

PostPosted: Tue Nov 04, 2008 9:13 pm    Post subject: Reply with quote

I wonder if it has the wrong type of elec pump fitted? some pumps push the fuel (mounted at the back near the tank, often under the boot floor), others pull (ie are usually mounted under the bonnet near the carb). I'm not sure though how to spot the difference when looking at a pump on a table.

The Mk2 A40 had an electric pump I think, it'd be worth checking to see where that one was located and make sure your installation is the same. Saying that a mechanical pump should work fine though, my Mk1 A40 had a mechanical pump and had no problems, although I had a 1.25" SU carb fitted to that, rather than the original Zenith.

A pump ticking away continuously, if that is what is happening? does suggest a supply issue of some kind. It should stop ticking within a few seconds of turning the ignition on.

Was the elec pump a new one? has your mechanic tried swapping it for another to see if it makes any difference?

Of course the fuel thing could be a red herring and it may be part of the ignition system breaking down when warmed up.

Rick
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pigtin



Joined: 23 Nov 2007
Posts: 1882
Location: Herne Bay

PostPosted: Tue Nov 04, 2008 9:38 pm    Post subject: Reply with quote

Sounds like the coil breaking down when it gets warm. Might be worth changing it.
Don.
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Keith D



Joined: 16 Oct 2008
Posts: 962
Location: Upper Swan, Western Australia

PostPosted: Tue Nov 04, 2008 10:42 pm    Post subject: Reply with quote

Hi Marco,

A friend had the same problem many years ago with a Ford (Capri?) and it took many months of hair tearing and abusing the car before he found the answer.

The air hole in the filler cap gasket had not been punched properly or was blocked, (I can't remember which) and air could not get into the tank to replace fuel used. He put a hole into the gasket and had no further trouble.

I hope this is all that is wrong with your Austin

Keith D.
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peter scott



Joined: 18 Dec 2007
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Location: Edinburgh

PostPosted: Tue Nov 04, 2008 11:17 pm    Post subject: Reply with quote

Keith's suggestion sounds very interesting but if it's not that it would be helpful to establish what the fuel pump is doing when the car conks out.

The continuous ticking could be due to pumping air rather than petrol. This will normally result in very rapid ticking, almost a continuous clatter. Alternatively the pump could be pumping petrol into a flooding carburettor. This is more likely to be a slower tick, maybe one per second.
A look under the bonnet would confirm this as you will see a wet carburettor and a strong petrol smell.

Peter
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LRossi



Joined: 04 Nov 2008
Posts: 2

PostPosted: Tue Nov 04, 2008 11:58 pm    Post subject: Reply with quote

Thank you all for your prompt, kind and helpful suggestions! I'll print these off and take them to the garage with me after I've got my own car through its MOT, sigh...
I should also have added that the A40 lay dormant for three months or so outside the mechanic's garage after a Calor Gas truck helpfully reversed into it when it was parked in the yard awaiting attention, and insurance blamestorming commenced: another saga which is running to this day! Suffice to say, a replacement front wing didn't cure the problem either...
I'll report back with an update on the conking out scenario as soon as is feasible: many thanks again in the meantime!
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Guy



Joined: 25 Apr 2008
Posts: 25
Location: Wakefield

PostPosted: Wed Nov 05, 2008 7:55 am    Post subject: Reply with quote

The first thing I would look at if a car stops when hot then starts when cold is the radiator and cooling system.
Is the car overheating causing a vapour lock in the fuel lines or carb?
Cheers
Guy
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Greeney in France



Joined: 06 Mar 2008
Posts: 1173
Location: Limousin area of France

PostPosted: Wed Nov 05, 2008 8:55 am    Post subject: Reply with quote

I would suspect the electric pump too, I have heard that changing an electric pump from a mechanical one can cause pressure problems and cutting out because of flooding or lack of fuel there are pressure regulators to correct it.
Do you have a filter in between the tank and the pump? a good idea especially after having tank problems before
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peter scott



Joined: 18 Dec 2007
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Location: Edinburgh

PostPosted: Wed Nov 05, 2008 11:59 am    Post subject: Reply with quote

Greeney in France wrote:
there are pressure regulators to correct it.


There are two types of SU pump, high pressure HP and low pressure LP.
I think it's true to say that the HP is used when mounted at the tank and the LP when it's mounted in the engine compartment.

The only difference between the HP and LP is the strength of the diaphram spring and this is an easy to obtain part and easy to change.

Peter
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clascar



Joined: 27 Oct 2008
Posts: 83
Location: mid cheshire

PostPosted: Wed Nov 05, 2008 7:28 pm    Post subject: Reply with quote

I would start with the basics when it conks out again, take a mechanic with you. Has it got a spark? is fuel getting to the engine? is there enough compression? If all three are there assuming the timing is undisturbed it should run. If it is fuel then it should be evident by nothing or little coming out of the pipe from the pump to the carb. I had a corsa that nearly drove us mad until we found moisture lying in a low point on the fuel line. When the weather went cold it froze causing the car to stop. It took ages to find. Another suspect could be the condensor. These terrible little things give all sorts of symptoms when faulty.
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ka



Joined: 03 Dec 2007
Posts: 600
Location: Orkney.

PostPosted: Thu Nov 06, 2008 8:41 am    Post subject: Fuel pump, Reply with quote

Just to add to the confusion, all the advice relating to the SU pump is probably correct, but what kind of pump is fitted? My Facet ticks all the time!


KA
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euronerd



Joined: 13 Oct 2008
Posts: 16
Location: Yorkshire

PostPosted: Thu Nov 06, 2008 11:44 am    Post subject: Reply with quote

It would help if you could ascertain exactly how it stops. As clascar suggested, take a mechanic with a good ear along, and the exact manner in which it stops should give him plenty of clues. This will ensure of course that the car performs perfectly. There's no point my trying to put every scenario into words here but it's worth bearing in mind that about 90% of involuntary stops are caused by electrical faults. If as you say, the car came with this fault, you could also look for clues the previous owner left as s/he searched for a cure, but you've probably done this already.

Geoff.
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Nic Jarman



Joined: 05 Oct 2008
Posts: 1035
Location: Stoke by Clare, Suffolk

PostPosted: Thu Nov 06, 2008 2:16 pm    Post subject: Reply with quote

Hi, as keith said the filler cap vent may be blocked, I had this on a motorbike and it caused similar symptoms. A plastic push in cap would let you know this one. Electrics are often best tested by substitution, borrow a coil if you can and replace the condenser. My Midget conked out in traffic and that was caused by the fuel vapourising in the float bowl with a strong smell of petrol. A heat shield cured that. The clues are all there you just have to use your ears and nose. Good luck.
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Jim Walker



Joined: 01 Oct 2008
Posts: 124
Location: Chesterfield, Derbys.

PostPosted: Fri Nov 07, 2008 11:26 pm    Post subject: Reply with quote

I cannot remeber what kind of petrol filler cap an A40 has, but Morris Minors often suffered similar symptoms. The reason was simple. The Minor used a vented cap with a small hole in the centre. If the cap was lost an apparantly identical cap was sometimes fitted with no hole, causing a vacuum in the tank as petrol was used. I never found out for what the unholy cap was correct fitment. With this problem a sucking sound is heard when the cap is removed.
If your car has SU carb(s), freezing is a distinct possibility and is more reliant on humidity than ambient temperature. All carbs work by causing a depression in the choke tube. The pressure drop causes a temperature drop and if the air is very moist can cause the piston to freeze in its chamber. Fixed choke carbs like Zenith and Solex are less prone to freezing in cars (though they can in aeroplanes). A Morris Minor I had suffered this problem sometimes, but it always stopped in about the same place after leaving home. After two or three minutes it re-started normally.
"Long Range" diagnosis is a tricky and often misleading business. My neighbour once asked about a 'squeak' which seemed to happen 'when I turn a corner' and 'disappears when I put the brake on'. I suggested play in a front wheel bearing was allowing the brake disc to tilt and rub on the pad. After he had spent all day playing around with (and over-adjusting) the wheel bearings with no success he asked me to call round and listen. To me his 'squeak' was a 'creak', immediately recognisable as a dry and worn out prop -shaft universal joint. It seems he also always pressed the clutch when he braked (!)

Jim..
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