Fuel Vaporisation

[Peetee]

After a cold run of 20 miles where the heater struggled to provide hot air (yes it has been cleaned out - several times) on the return journey I shielded half of the radiator and down the motorway enjoyed toasty conditions in my 40 year old moggy whoile outside the frost glistened. However, as soon as the speed dropped and I stopped for the motorway exit the engine started to faulter and the last mile was stutter jump pop all the way. two hours later I was back on the road and all was well. I guess that was fuel vaporisation caused by additional heat in the engine bay - despite the fact that I have aluminium tape on the vertical fuel line and a sheild on the upper, curved section of fuel line.

[Chris Morley]

Peetee, thats nothing to do with fuel vapourisation. Last year I shielded half the radiator and soon got the same thing (overheating of the cooling system). Clearly a Minor needs more than 50% of it's radiator capacity.

I see BMCecosse is getting a hard time from some people. To those who think his opinion is worthless, consider that just because your Minor and many others has a problem it doesn't mean that all minors invariably suffer the same way. I've never had an exploding coil, faulty rotor arm or sticking fuel pump points - but I don't dismiss others who have experienced these problems.

Although I've known the fuel pump to click quickly, my Minor has never stopped due to fuel vapourisation, despite once being used in stop-start traffic when the temperature was a sizzling 99F . My engine is standard and the fuel pipe is right by the manifold. So what is it about some minors that causes this problem? I would bet that it is not a problem caused by the basic design because Minors sold well in far hotter countries than the UK and a fault like this would have quickly scuppered export sales.

My best guess? - maybe some minors get too hot because their cooling system simply isn't good enough - or maybe it's because modern standard unleaded fuel in the UK makes the engine run hotter than it did on 4 star. Both could cause unusually high under-bonnet temperatures, leading to fuel vapourisation.

[rayofleamington]

So what is it about some minors that causes this problem?

There are a huge amount of variables, including the exhaust make and the location of the fuel pipe. It is easy to imagine one exhust being a couple of inches nearer the fuel pipe than on another car. Underbonnet temperature will be another variable (e.g. efficiency level of the radiator). Other variables will come from the fuel pump - some pumps will cope with vapours far better than others as they do not all work as well as each other. Some carb inlet needles will slightly restrict the free flow of vapours helping to keep the fuel pipe vapour locked whereas others will be less restrictive.
The quality of fuel that you have in on that day will be different from other days as man/all fuel companies buy their fuel from different sources and the fuel itself will vary.

When commuting in the Midlands approx 15 years ago I regularly got fuel vapourisation in a regular 25 minute queue at 5-Ways island near Heath Hayes. I got this half a dozen times a year but was lucky that the queue wasn't 30 minutes long as the car was only just running by the time I got into the roundabout and despite spluttering and jerking round the island I always managed to get onto open road, and the problem was cleared in under 30 seconds.

I've not had it on the other cars (yet) but as you mention - some cars are more prone to it than others.

[Packedup]

or maybe it's because modern standard unleaded fuel in the UK makes the engine run hotter than it did on 4 star. Both could cause unusually high under-bonnet temperatures, leading to fuel vapourisation.

Another reason to pay a bit more for super/ Optimax/ Ultimate etc then

[Kevin]

Never had the problem - and have never heard of anyone having the problem either - until this thread !

Well if you had been in the queue to the National at Donnington last year you would have found a fair few drivers who would have disagreed with you.

I see BMCecosse is getting a hard time from some people. To those who think his opinion is worthless,

Actually Chris no one said his opinion is worthless, just that his view is ALWAYS correct (in his opinion) and no one else knows what they are talking about (in his opinion) but as you said just because you have not experienced it, you dont disbelieve others suffering from the symptons and if it was a bit of Minor Mythology why did Grumpys make a kit (that didnt make any difference anyway) to help with the problem and next time there is a big queue to reach the National (well over a hour) you will see the effects first hand.
I fortunatly didnt suffer to badly but the pump did try to impersonate a small machine gun at times in that queue.

[bigginger]

I don't think anyone dismisses other peoples problems with their cars because they haven't suffered them except Mr Ecosse. His opinions are just that, and just like mine, they're frequently wrong. I guess the difference is just that I try not to express them quite so emphatically and frequently.

[Chris Morley]

Kevin, Andrew, I'm not saying it doesn't happen to some Minors - clearly it does and it's been mentioned on this board many times in the past. However it doesn't happen to mine and it may well have never happened to any of BMC's either. Of course Scotland's temperature tends to be a bit lower on average....

If it were a basic design problem with the Morris Minor then everyone with an original car would have had this problem on every warm summers day since 1949. Because they haven't I suspect that fuel vapourisation is really only a symptom of overheating, not the actual cause.

In terms of dealing with the problem when it happens, I wonder how many of those cars in the Donnington queue were sitting there with their engines running? When the combustion stops the heat source vanishes. And of course you can always switch the heater on - yes it is uncomfortable on a hot summers day but its also a good way of reducing the water temperature very quickly.

Everyone's entitled to an opinion - and there's no law to say an individual has to change theirs just because loads of other people disagree with it. On a subject like this there's never going to be a real consensus because it's not covered by manuals or technical literature. Live and let live is the best solution.

[bigginger]

Live and let live is the best solution

My feelings exactly, and very much what I was saying. As I say, it's just that the sheer repetition gets to me every so often, my fault...

[Packedup]

The cars were last made in what, 71/72? So that's 33 or more years for everyone to have and then repeat the same opinions etc - And worse, only a hadful of years for them to have the world wide interweb to do it on!

So just think, all that concentrated opinion-ness being unleashed after years of bottling it up!

Maybe if it could be harnessed all that opinion energy from all sides could be distilled and used to power Minors in a greener future...

[Willie]

I too have never had this vapourisation stoppage over a period of forty
two years of driving Minors although I have had some frantic pumping at
times! It is obvious that the problem occurs under stationary or near stationary conditions which to me says that the cause is under bonnet heat
build up because there is no through air flow to disperse the heat. If I did have this problem I still think the answer would be to remove the fuel pipe
from the pump,straighten it, and run it forwards along the chassis leg to a
re-mounted pump which would now be on the inner wing just behind the radiator AS LOW AS POSSIBLE bearing in mind that the Minor pump is a 'puller' not a 'pusher'. Since heat rises, the lower fuel feed pipe
and pump positions would probably remove this problem for ever without
adding additional fans etc? It would also be interesting to know how many
of those who have had these problems are running hotter than standard
thermostats.

[rayofleamington]

It would also be interesting to know how many of those who have had these problems are running hotter than standard thermostats.

The Minor I had that gave these symptoms was running the standard thermostat. As mentioned already I've only had it on that car, and even then it never stopped completely - it only got to the spluttering stage.

If only I'd not been in Germany this week, then I'd be a lot closer to my first attempt at fuel line relocation.
I've just got to change the cylinder head, manifold, carb, exhaust, steering rack, steering column, gearbox, clutch linkages, m/c location, brake pipe routing, dash position and a few other things and then I'll be straight on to the fuel pump...

[MikeNash]

Just seen that today is Pride Day! Hope it all went well, Kate. Suppose you're resting now.

Ashamed to say that I saw a good idea a couple of months ago that much reduces the fuel vaporisation problem and forgot to pass it on.
Ian Bewster, a member out a Wellyn (?) Garden City and an all round clever bloke has rolled his fuel pipe from the tank out flat so the fuel pump is now on the engine bay floor over the forward hole - probably the coolest place in the engine bay. I think he said he'd been able to use the original fuel to carb flexible pipe which now passes up ahead of all the manifolding and exhaust pipery. All that's needed is a bit more wire for the electrical supply to the pump.

Now the fuel is hardly raised at all on its journey to the pump (reducing negative pressure in that bit) and the remainder of the run to the carb is under pressure as before with everything probably running cooler. All in all, a recipe for less vaporisation.

Brilliant, eh? How come no one else has though of this? Regards, MikeN.

[Willie]

MIKE, if you read back you will see that that is exactly what i suggested.

[MikeNash]

Sorry Willie!
Nov 16th last year I see. So much on this item I lost the thread of it! (Sorry about that.) But it wasn't till I saw an installation I fully understood it and realised how simple it was. Regards, MikeN.

[bigginger]

Discovered on the way back from the national, BTW, that tipping water over the fuel pipe to cool it DOES seem to mean that the engine will run again fairly quickly. Repeat as necessary - but it does get you home. Thank you to the good people of Uxbrige for the help pushing

[Pyoor_Kate]

Just seen that today is Pride Day! Hope it all went well, Kate. Suppose you're resting now.

Cheers Mike! It went fine, no problems at all - I actually had some mild vaporisation issues with the mech pump at some point (I can't recall when) - so bodged a heat shield between the exhaust and the upper section of the fuel line (the routing is a bit different on the Ital engine with a mechanical pump). Rebecca was flawless and astonishingly popular - *waves at the relevant thread* - the only problem being my left leg getting *really tired* after lots and lots of miles... I think the clutch may have suffered too from being slipped all the way round the Pride route. But it was no worse than a bad traffic jam really

[ColinP]

BigG,
Thanks for the info about the water - I had thought about lashing together a "simple" cooling device:

Take a length of cheesecloth (dishrag) wrap around the fuel pump and inlet pipe. Add water, and the cooling as the water evaporates should reduce the vapourisation.

Stage 2: use the windscreen washer pump to add water while driving....

Stage 3: use a temperature sensor & electric pump to do it!

I didn't get beyond stage 0 - so far (touching wood rapidly) I haven't needed it....

Colin

[minor_hickup]

How about that exhaust wrap you see advertised for manifolds? Surely if it can keep heat in it can keep it out! I don't know how easy it would be to put on the supply to the pump. Sorry if this has been suggested before.

[Kevin]

that tipping water over the fuel pipe to cool it DOES seem to mean that the engine will run again fairly quickly

You have jogged my memory with that one Andrew many moons ago during a very hot summer I had problems with an Anglebox that I was running at the time and was told part of the problem was caused by the glass domed top of the pump causing fuel starvation and the easiest way to cool it was to cut an orange in half and put it over the dome for a short while to cool things down (and it worked) its the only time I can remember having an orange as part of the spares kit.

[bigginger]

Sounds good Food AND a running engine - mmmmmmm...