Modern petrol and starting problems

[silverboydreamer]

Don’t know if anyone is having similar problems starting my B as I am experiencing?. The car is on zeniths and I refurbished them two years ago, initially I had starting it from cold, this proved to be fuel evaporation which resulted in the carbs running dry and having to be filled again when trying to start. I think also the accelerator piston skirts dried out making them stiff and so unable to form a seal in the carb cylinder so not able to push fuel out of the nozzles in the carb Venturi resulting in very poor starting. I overcame this by installing a electric prime pump which enabled me to fill the carbs prior to starting, this was partially successful, I worked out that if I primed the carbs prior to using the car and leaving the accelerator piston skirt to soak, ie make the leather skirt re-wet , after pumping the accelerator 2-3 timers the car started ‘on the button’. Problem solved!.

Now 2 years later the problem has returned despite having followed my usual start up procedure, after checking if there was fuel coming out of the brass nozzles ( there was not ) I took out accelerator pumps and opened the skirts and refitted, bench tested the carbs and on the engine and fuel was ejected from the nozzles when accelerator was depressed. The engine started easily, problem solved, or so I thought.
Two days later came to start the car, no start, checked the nozzles and no fuel coming out despite the carbs being full, there was no resistance in the accelerator pump arm (there was after my last reassembly) so my conclusion is that again the accelerator pump skirt is stiff and so not able to pump out fuel.
I have come to the conclusion that the modern petrol not only evaporates very quickly particularly in the engine is hot, it also effects the suppleness of the leather skirt on the accelerator pistons, these we new two years ago but now look as if they need replacing.
Has anyone else had this problem, if so did you find an alternative answer to mine, I’d be interested to see what others have today. This modern fuel is really not compatible with zeniths and when they increase the bio fuel content things can only get worse.

Further to the above I have replaced the accelerator pump on both carbs ( a fairly easy job) and can report starting is again easy to do, namely switch on primer pump, turn over the engine till the oil light goes out, pump the accelerator 3-4 times, depress accelerator part way, then turn the key and the engine starts either straight away or the next try, switch off primer pump and away I go. I am now using Esso premium which I hope will improve the situation I have found myself in.
I enclose two pics that show the difference between the accelerator pumps old and new, you can see a bigger flair on the skirt of the new pump, this makes a better seal to the chamber and as a result better pumps the fuel into the nozzles.
The new ones are on the right.

[neilbardsley]

I can't answer for zeniths but with webers if I come back to the car after 2 days it starts almost instantly. I do try to put the higher cost fuel in it.

[hashman]

You could try ESSO Synergy Supreme+ 99 which is ethanol free.

Karl

[Hugo 356]

Many years ago I was discussing switching to a pair of Zeniths Eric Studer had. Before re-commissioning he said they would need soaking in Neats foot oil. Possibly put off by the foot oil I stuck with the Solex's but the conversation stuck in my head.

Just googled it and it's Neatsfoot oil leather softener and not Neat's foot oil as I had thought

https://en.wikipedia.org/wiki/Neatsfoot_oil

On Andy's advice I have switched to Esso high octane as I understand it is ethanol free in most places. See:

https://www.ddk-online.com/phpBB2/viewt ... ol#p604530

[roy mawbey]

Interesting thread. My 356A is still running with accelerator pumps in my Zeniths from when I bought my car in 1969. I do have some new spare ones bought maybe 10 years ago that I have refrained from using. The brass squirter's in the carbs are still working efficiently and therefore the aged leather skirts I have always presumed must be doing the job properly.
A lot of other parts in the carbs I have changed but not those.
Until the advent of Ethanol and unleaded I used always the 95 octane. Then with unleaded 95 octane I started to notice the difference. If the car was left for a week, my normal 5 presses of the accelerator would not guarantee a normal firing up. It would if the car was left for 2 days but not 5. Once it does start never a problem to restart.

So I determined eventually Ethanol was causing evaporation in the carbs bowls. So since then have used the Shell and Esso higher octane which seem to stop a lot of sooting up of the exhaust tails.A decent run and the chrome pipes are a nice straw colour and they carbs are in tune and perfectly dry. I have presumed the 97 octane still has Ethanol as I also thought my original mechanical pump is not so efficient as an electric pump. If I get in the car after when the car has not been used for a couple of weeks those bowls need refilling by just turning the motor with no accelerator for about 50 seconds. Then 5 presses of the pedal and it will usually fire up.

I have thought every two days go in the garage 5 presses start the car but it needs driving then so not a good idea really plugs need to get hot etc etc.

I have few Esso garages around so is this Synergy Supreme +99 special ? The Esso product I used had a different name but was their highest priced one.

It is a real pain not getting an instant start. I might well look out for it and try. With 10% Ethanol on the cards it will only get worse and all those rubber pipes , seals, etc will suffer too.

Roy

[oldtimer]

Interesting thread . I have always put the most expensive highest octane fuel in my Porsches as they generally are expensive to run anyway !

My 1964 356C on 6volt electrics with Zeniths was always tricky to start after a long rest , previous owner had fitted an auxiliary electric fuel pump to switch on and run for a short while before trying to start up . Take care not hydraulic lock the engine from over enthusiastic use. Difficult starting remained an issue if not used regularly. Car stilll used its mechanical pump of course.

My 1955 356 'outlaw' on 12 volt electrics 912 motor and Solexes is better . The pre A's have a push button starter wired independent of ignition so you can turn engine over to turn over the mechanical pump and fill the carburettor bowls with no sparking .

Ethanol in fuel is a real nightmare for 'old' rubber parts , fuel hoses etc

[Ashley James]

I have the same problems with Zeniths and I agree that accelerator pump issues are the cause. I’ve ordered a pair of Chinese Solexes as recommended by Neil because they have a diaphragm and should help. I’ll report back, but I hear good things from those who’ve fitted them.

[silverboydreamer]

It would admit to being a fuel tart, buying from the nearest (BP) or cheapest ( Morrison’s) not realising that there was petrol around that didn’t contain ethanol, all pumps including the performance fuels show E5 on them, indicating they contain ethanol. After see your posts it seems Esso is the only one who acknowledges their premium brand is ethanol free but has to comply with legislation and put on a E5 label on their pumps even though there is none in the petrol.

I will in future fill up with Esso premium whenever possible, it’s more expensive to run but might be cheaper in the long run vis-à-vis having to replace various bits in the future that are effected by ethanol containing petrol.

[hot66]

Don’t assume it’s always ethanol free ... depends where in the U.K. you are. Here in the north it’s got ethanol

[Ashley James]

If I remember correctly, Sheffield University did extensive research into fuel vaporisation including measuring all the fuels they could buy. The conclusion was that ethanol varied enormously and could be as high as 20%. Only by buying one of the high octane fuels could you avoid it. Can’t remember which one. Their testing was done on an XPAG engine and they recommended 5% central heating oil and premium fuel if you had the problem.

I had terrible problems with my MK VI Bentley because the under bonnet temperature could be extremely high, we’ve never had it with the Healey, even in 40 degrees, but the 356C is a old git to start if it’s left for a week or two and I’m convinced that’s fuel evaporation from the carbs made worse by accelerator pump plunger diaphragms drying out.

[Winston Teague]

I can't really understand why one would assume that some Chinese replica carbs would be an improvement. They could contain a whole host of unknowns/adjustments that can have a major bearing on the running of your engine. Surely if you have decided to veer away from original, a pair of 40 IDF Webers is a good, known, reliable, proven solution, commonplace enough to be able to set up with the wide experience of others.....That price saving could soooooo easily be consumed sorting problems after installation. My car came with webers installed and they have been largely trouble free (1 pr of Accellerator pump diaphragms in 16 years/24000 miles) and Rolling roads understand them. W

[Winston Teague]

Always worth remembering that, if you pay for labour on your car, the cost of this will FAR outweigh the parts cost, so buy the parts that will need the minimum amount of labour......

[Ashley James]

I can't really understand why one would assume that some Chinese replica carbs would be an improvement. They could contain a whole host of unknowns/adjustments that can have a major bearing on the running of your engine. Surely if you have decided to veer away from original, a pair of 40 IDF Webers is a good, known, reliable, proven solution, commonplace enough to be able to set up with the wide experience of others.....That price saving could soooooo easily be consumed sorting problems after installation. My car came with webers installed and they have been largely trouble free (1 pr of Accellerator pump diaphragms in 16 years/24000 miles) and Rolling roads understand them. W

As far as I can see, anyone who’s bought them has been pleased because they work straight out of the box, while those on the Registry Forum who’ve fitted Weber’s seem to have trouble getting them right.

[Winston Teague]

Hmm. Remember that American fuel is not the same as ours. I hope it works out well, keep us posted. W

[neilbardsley]

I can't really understand why one would assume that some Chinese replica carbs would be an improvement. They could contain a whole host of unknowns/adjustments that can have a major bearing on the running of your engine. Surely if you have decided to veer away from original, a pair of 40 IDF Webers is a good, known, reliable, proven solution, commonplace enough to be able to set up with the wide experience of others.....That price saving could soooooo easily be consumed sorting problems after installation. My car came with webers installed and they have been largely trouble free (1 pr of Accellerator pump diaphragms in 16 years/24000 miles) and Rolling roads understand them. W

As far as I can see, anyone who’s bought them has been pleased because they work straight out of the box, while those on the Registry Forum who’ve fitted Weber’s seem to have trouble getting them right.

There seems to be an unwarranted dislike of Webers on the Registry.

However, they work well for many

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