Fuel Vaporisation

[Multiphonikks]

Well okay then

N

[MikeNash]

Thanks Mr Cam!
Your installation seems the definitive solution. Is this braided line the same as we often see between the pump and the carb ie attatched by jubilee clips? Is the Facet pump easily obtainable?
Finally, what do you think of an SU mounted low? I think their output pressure is about 2 psi. Am I right? MikeN.

[Cam]

Here is a picture of my FACET pump in situ:



and the regulator in place of the original pump (ignore the black pipe):



The braided line is similar just a bigger bore. The pump is available from most motorsport places and Mini centres.

An SU pump mounted low would improve things, but if you are going to THAT trouble then I'd rear mount a pusher pump and leave the original copper line in. The original pump MIGHT be able to be left in situ (not working) but I'm not 100% sure on that.

That way, the car looks original unless you look under the back!

The original pump's output will be just below 2 psi I think as that's around the pressure than the needle valve in the float bowl fails to shut off. Anymore pressure than that and it won't close and you'll have fuel everywhere!

[bmcecosse]

I have NEVER had any form of fuel vaporisation problems - either with any of my Minors or any of my Minis - and on the Mini the fuel pump and feed pipes are very close indeed to the lcb exhaust - no problem at all - either in heavy traffic or when hammering up hill and down dale. I suspect your problems are somewhere else - don't blame the poor old fuel pump ! On a Minor it's miles away from the heat sources !

[Multiphonikks]

Hi BMC.

We are talking SLOW - ie, sub 5 mph for a few hours after being stuck for 45 mins with the engine running

[bigginger]

All the tales of the Minor fuel pump being prone to vapourisation must be wrong then...

[MikeNash]

Bmc,
I don't think anyone blames the pump. Its the fuel getting too hot and turning to gas whch is then vented out the float chamber breather so starving the engine that stops the car.(Unless like me you direct it back into the carb.) If you've never had trouble it doesn't mean you've not had vaporisation. With a fuel pump counter fitted you can see the short bursts of pump activity at short stops like traffic lights, or better still, railway level crossings which occur most times except in winter. It may be that in Scotland you're at an advantage by being just that bit cooler.
MikeN.

[Cam]

Bmc,
I don't think anyone blames the pump. Its the fuel getting too hot and turning to gas whch is then vented out the float chamber breather so starving the engine that stops the car.(Unless like me you direct it back into the carb.)

It starts to vapourise BEFORE the pump and the pump is then left trying to suck vapour and not fuel whereby it ticks away rapidly. The float bowl is then left with no (or a sporadic) fuel input and consequently runs dry which stops the car.

If you've never had trouble it doesn't mean you've not had vaporisation.

Very true!

With a fuel pump counter fitted you can see the short bursts of pump activity at short stops like traffic lights, or better still, railway level crossings which occur most times except in winter.

You can hear the ticking over the engine at idle so you don't really need a counter.

It may be that in Scotland you're at an advantage by being just that bit cooler.

Quite possibly so, also less traffic jams compared to say inner London!

BMC,
The fuel pipe arrangement is totally different to the Mini and so you can't compare the two. Minis usually either have an electric pusher pump at the back (pressurising the fuel and eliminating the problem) or a mechanical one low down on the engine block which pressurises the fuel BEFORE it gets to the heat source, again, eliminating the problem.

The low (neg) pressure fuel line on a Minor runs right next to the manifold so it causes problems. If it was further away or pressurised it would not be an issue.

[MikeNash]

Thakns for the piccies and details, Mr Cam.
Mr Cam says
"..it starts to vaporise BEFORE the pump..." Exactly.
and then
"You can hear the ticking over the engine at idle so you don't really need a counter."
Well, that not the purpose of the counter, but my point is that at the onset of vaporisation, you'll idle away quite safely and as you pull away and when the pump is inaudable the vapour is pulled through in rapid strokes. No problem - you've got away with it. But shows that the onset of vaporisation is ahead of the pump and I suspect that a big part of the problem lies where the exhaust pipe is close to the fuel line - in my car they're only 1 3/4 inches (4.5 cm) apart. Others may be better or worse.
But what are we doing for poor old Kate? Perhaps a wedge of household glassfibre insuation between the exhaust and fuel line and some more stuffed between the carb and exhaust manifold? MikeN.

[ColinP]

Mike,

Thanks for pulling us back to topic!

Suggestions update:

1) for immediate relief use "Deep Freeze" aerosol. This is a cooling aerosol, so it will cool down anything you spray it on. This is sold by Chemists - other varieties are sold by Electrical component shops (e.g. Maplin). DO CHECK TO SEE IF THEY ARE FLAMMABLE BEFORE USE. They used to be inert, it's possible that they are now compressed hydrocarbons - not the sort of thing you should spray near a hot exhaust.

2) for special events, a cool-gel pack from the freezer, kept in a freezer bag (or that old sports standby - a heap bag of frozen peas) - wrap around the affected part. (also works for sprains).

that should help get the car running again - however, if the road traffic hasn't changed (e.g. 85 mile tail back on M25), it will need to be re-applied.

Longer term solutions:
I think Cam has a really good one, but it won't appeal to some people (specially the concours interest). That could be managed by some sort of "clip-on" cooling accessory which can be easily removed etc. I'm still thinking here, but my first thought is some form of peltier device to provide cooling (solid state, run from 12v dc power by crocodile clips - easily removed), operating on the fuel pipe before the pump, and possible also the pump....
All the cooling bits I've seen are either very expensive, or designed for cooling computer chips (small flat square things - not rounded like pipes or SU pumps).

Suggestions?

Colin

[rayofleamington]

I have NEVER had any form of fuel vaporisation problems - either with any of my Minors or any of my Minis - and on the Mini the fuel pump and feed pipes are very close indeed to the lcb exhaust - no problem at all - either in heavy traffic or when hammering up hill and down dale. I suspect your problems are somewhere else - don't blame the poor old fuel pump ! On a Minor it's miles away from the heat sources !

Cloud cukoo land!
Fuel vapouristation means the pump is running on fumes and ticks rapidly, followed by you starting to run out of fuel. Are the hundreds of Minor owners who have experienced this in Midlands and London traffic suffering from mass dellusions?
I think not! Keep up the good work

[Cam]

Thakns for the piccies and details, Mr Cam.
Mr Cam says
"..it starts to vaporise BEFORE the pump..." Exactly.
and then
"You can hear the ticking over the engine at idle so you don't really need a counter."
Well, that not the purpose of the counter, but my point is that at the onset of vaporisation, you'll idle away quite safely and as you pull away and when the pump is inaudable the vapour is pulled through in rapid strokes. No problem - you've got away with it.

Mr Mike, the vapourisation is only really a problem when stationary (or VERY slow moving in traffic) at which point you can hear the pump and hear it starting to speed up so you usually have quite a warning that things are starting to heat up. I had exactly this when stuck in that hour traffic jam on the M6 coming back fromt the website rally. My pump started getting faster but the car never cut out, so I was suffering with vapourisation but not enough to run the float bowl dry and stop the car.

I can see the point of a counter if you have a loud radio, but not for a standard car with no radio installed as you can hear the ticking when you need to (assuming your hearing is OK and the pump is an original SU type and ticks at normal volume! ).

But shows that the onset of vaporisation is ahead of the pump and I suspect that a big part of the problem lies where the exhaust pipe is close to the fuel line - in my car they're only 1 3/4 inches (4.5 cm) apart. Others may be better or worse.

That's exactly it for the close heat source. But the low pressure (sucking of the pump) aggrivates the problem by reducing the temperature at which the fuel vapourises. Fuel at a higher pressure vapourises at a higher temp.

But what are we doing for poor old Kate? Perhaps a wedge of household glassfibre insuation between the exhaust and fuel line and some more stuffed between the carb and exhaust manifold? MikeN.

Well... years ago I had the unfortunate experience of repairing a Renault 5 GT Turbo. This car had a massive electrical fault caused by some idiot installing a huge audio amplifier and managing to melt and mess up the electrical system so badly that the car would not run! Anyway... the engine is carb driven and it had an 'anti-perculatory system' for when the engie bay temp got too hot. This was basically a small fan with a plastic nozzle pointed at the base of the carb to cool the fuel bowl down via a thermoswitch when things got too hot!

Maybe Kate could rig up a kind of heat sink on the fuel pipe and use a small ducted fan to blow cool air over it when in traffic. I'm sure a scrapyard hunt would provide the bits needed! I don't think a PC cooling fan would be powerful enough and it would need ducting anyway to concetrate the air.

[ColinP]

OOps

Please DON'T use "DEEP FREEZE" - I've just read the side of the can :

"pentane, alcohol, diethyl ether" - it's rather flammable!

(I'm not going to recommend squirting it into the intake to get the engine started!)

Try one of the electrical cold sprays....

Colin

[Matt]

or a can of compressed air....

[bmcecosse]

Sorry - not convinced. My Minor fuel pipe is miles away from any heat source. Never had the problem - and have never heard of anyone having the problem either - until this thread ! I still think it's something else - now I have had/heard of overheating coil.

[bigginger]

...except where it and the pump are directly above the exhaust pipe as it leaves the car. Believe what you please - it remains true.

[MikeNash]

Re bmcecosse,
If your fuel line's well clear of the exhaust then you've got the ideal installation! Have you a re-routed/non-standard exhaust system?
Re Mr Cam (shall I drop the Mr? Its only a term of respect!)
My counter's purpose is fuel flow metering, and this subject of vaporisation is incidental. But believe me, vaporisation is not just a stationary or slow speed phemona, at least on my car. My efforts to measure fuel flow in high summer are restricted to early (and so cool) mornings because of errors arising from this problem.
But for our Kate, as I read she needs quick and instant mods for other peoples' standard Morrises that can be pulled off immediately after the show. (Is that right Kate?) And so bunging insulation seems the best. Perhasp we should have a go at it to help her. Regards, MikeN.

[Multiphonikks]

Excellent Mike ;)

Kate and I are going to be fine - but as you say , it's other people's cars! (We'd like to be able to take other people's cars along too!)
BMC - I think you're very lucky. Perhaps you should write a book

[rayofleamington]

Sorry - not convinced. My Minor fuel pipe is miles away from any heat source. Never had the problem - and have never heard of anyone having the problem either - until this thread ! I still think it's something else - now I have had/heard of overheating coil.

Exactly - as the problem is very well known, and as a hot coil doesn't cause a racing petrol pump, I rest my case ;-)

For the majority of Minor owners who know that the problem of a racing petrol pump, followed by running out of fuel in the carb when in traffic on a hot day (including the hlaf dozen people conked out on the way to last years national Rally) is caused by the fuel getting warm... watch this space in about 2 weeks for a possible solution ;-)
(hmm - now I hope it actully fits together )

[Cam]

Re Mr Cam (shall I drop the Mr? Its only a term of respect!)

Please yourself Mike, I get called lots of things!

My counter's purpose is fuel flow metering, and this subject of vaporisation is incidental.

Gotcha!

But believe me, vaporisation is not just a stationary or slow speed phemona, at least on my car. My efforts to measure fuel flow in high summer are restricted to early (and so cool) mornings because of errors arising from this problem.

True, but it's far more prevalent at low speeds as the cooler fuel delivery slows up and the air cooling drops more. Of course the exhaust manifold heat issue is there at high speeds, but mostly it does not USUALLY cause a problem. Never come across a high speed fuel vapourisation problem! Anyone else?

But for our Kate, as I read she needs quick and instant mods for other peoples' standard Morrises that can be pulled off immediately after the show. (Is that right Kate?) And so bunging insulation seems the best. Perhasp we should have a go at it to help her. Regards, MikeN.

Aye. Well, the insulation sounds good, but the fan/heatsink idea can be installed/removed quite quickly and easily too. But if the insulation works then go for it!