Vapour lock

[dannels]

Hey all

I was at Brooklands this weekend and whilst in a long queue to get in, suffered for the first time with fuel vapourisation.

Has anyone tried heat shielding the fuel line over the engine ? Did it make a difference? Am I better focusing on cooling the water more? Not sure I want to go electric fan due to having to remove either the fan or the louvres from the rad - perhaps a shroud for the fan would improve the existing fans effectiveness....

All views appreciated as always!
Here's a pic from the weekend - leaving with a cool engine!
 
Cheers
Dave

[brian]

I will be interested in any responses as my Flavia Sport is similarly affected. Part of problem MAY be that air inlet for carbs is a downwards facing hose on air filter which draws air in over exhausts. I am experimenting with curved hoses which gather air (hopefully cooler) from further forward and so help reduce overall carb temperature. I think it is the carbs getting hot as they do sit right over the heads of the flat 4. The weather has been so cold not met problem - yet - this year.
I realise the Flaminia has the air filter above the carb/s so may not be any help.

Brian

[chriswgawne]

This is really all about modern fuels isn't it. Back in the day, our cars didn't have these problems. The only solution that I know works 100 % is to run a 'flow and return' system by running a return to the tank so that one is always feeding the carb with coolish fuel.
Chris

[simonandjuliet]

I think that a lot of Aurelia owners have experienced this problem and have had varied success in dealing with it

With mine, I had a bonnet vent and good cooling and never really suffered, but as Chris says, maybe it would be a different matter with modern fuels

Good luck !

[dannels]

I guess in the late 50s when the Flaminia was designed there weren't really traffic queues that we experience now - so it wasn't a major design consideration.

I do wonder about the wisdom of running the fuel line to the carb so closely over the engine. I may have a punt at the cheapest option of insulating that whilst I look into a shrouded fan to up its effectiveness a bit...

Would still like to hear from anyone who has had success in this area!

D

[ColinMarr]

I have experienced vapour lock problems with B20 and Flavia back in the days of 5 Star petrol, but I am sure these problems are worse now with modern fuels. It is not only vaporisation at the carbs that causes problems; it can also be at the fuel pump. On my Flavia the pump was directly above one of the exhaust pipes and it could get really hot.

As Chris has said, having a flow-and–return system helps enormously, as does having an electric pump. Used normally just to prime the system, but when things get hot an electric pump can be switched on just to help get a bit more flow.

Colin

[dannels]

I'm running an electric pump - but I still experienced the problem - so whilst it probably helps avoid the issue (over the mechanical pump attached to the engine) it's not a solution

[Charles Frodsham]

Hi Dave

Are you running just an electric fuel pump or both. My PF has only an electric pump in the boot. The engine pump would add heat I guess.
Is there an issue with heat transfer to the carburettor. I would be interested to know what spacers or gaskets are used. Has anyone tried using additional insulation?
Is it possible to bring the fuel pipe via the bulkhead to the rear of the carbs to avoid heat from manifolds?

My PF sometimes idles faster when very hot. Not sure if this is related or not?

Charles

[oomejulie]

Oh no!!!
Hello all - I am a newbie with a Flaminia 3C 2.8 Convertibile.
Two weeks ago (in the middle lane at Hyde Park Corner of all places) and on a hot day, the engine cut out completely and would not start for 45 mins.
During that time I replaced coil, condenser, removed fuel supply to carbs to check flow and did about everything else conceivable. On the 47th minute it fired and took me to the destination without problem.
The return journey was worse and I shan't bore you< Since the rad has been off for rebuild - but they didn't charge me as nothing was wrong. Deep depression as I had hoped that was the problem. I am in the process of fitting a new fuel pump as that was recommended.
The only other tips I have been given are: breathing to the tank (cleaning out tomorrow), and MAYBE (as  I noted when plugs out in the sun in Hyde Park) the carbs being obstructed in some way or too lean. I hadn't ever realised that fuel cools as well as propels.
My last hope - and then I read this! Will let you know.

[dannels]

I've now insulated the fuel line to the carb but its not had a good test since. I'm heading to Flywheel in Bicester on the 2nd July - so that should be a good test as there will be big queues no doubt. Will report back...

[simonandjuliet]

Just to check - you are not running an electronic ignition system are you ? My brother in law's Fulvia had a problem with that produced a similar problem - having said that, as we know Flaminias and Aurelias do have fuel vapourisation problems ....

[Charles]

I also have a 2.8 3c convertible which used to give problems when trying to restart the engine if left for a few minutes when hot - although it has never cut out when running.  I happened to fit a Pertronix electronic ignition system for other reasons (kit for an Aurelia which required a small mod to the magnet ring to convert to the six lobed Flaminia cam) and I have not had the problem since.  I can't explain this as I was convinced that the problem was vapour locking and I don't see how a better spark would help but, nonetheless, my hot starting problems are a thing of the past.  The added bonus is that the engine now runs more smoothly at low revs when hot, previously there was a very slight, almost indiscernable, misfire when hot that I just couldn't get rid of.
Another problem I have suffered is blockage to the fuel pump and filter due to crap in the tank and I know that I should get around to cleaning it out one day.  For now I just make sure that I don't allow the fuel level to run low and I check the pump and filter regularly.

[dannels]

Mine is running electronic ignition as well. The issue I experienced was definitely no fuel entering the carb when hot

I've fitted the below as the cheapest and easiest potential fix and so far so good. I'm also working on a shroud for the radiator to better direct the airflow from the fan

Cheers
Dave

[peteracs]

Hi

Quite a few of the Beta owners have suffered from crud in the tank, but that is usually pretty indiscriminate if running hot or not, so suspect your issues are at the carb end.

As to hot start with/without elec ignition, maybe related to the coil/points? I would have thought the electronic ignition should produce a better/cleaner pulse on the coil, so resulting in a stronger spark maybe, and as the coil will most likely be at its 'weakest' when hot (more internal resistance), then the elec ignition tips it over the edge to effect decent starting?

Peter

[Brian Long]

My Flaminia used to be hard to start when it was hot. Turned out that it had a 12 volt coil ( instead of an 8 volt one) fitted in series with the starting ballast resistor. This effectively reduced the voltage to the coil when hot and hence made it hard to start.