Thanks for providing a little more information Riisu. I am no expert but happy to share my limited knowledge.. From that which you type it seems you may not be mechanically in tune with your Porsche... but are keen to gain understanding..before handing it over to someone else to repair for you ...?
My suggestions were related to simple tests, to establish whether the issue was down to lack of sparks or lack of fuel.
As you seem to think for whatever reason your issue is fuel related we will go with that given as STANDARD your fuel system would have been pretty basic... You have not identified the carbs fitted to your car and whether the fuel pump is mechanical or electrically operated. As I had suggested, given the passage of time much could have changed relative to your 911`s original specification..
In terms of sensors, again dependant on the carbs you have, there may be an electrically operated Auxiliary enrichment device that relies on the operation of a micro switch to energise an solenoid (electrical valve) to act as an automatic choke to assist cold starting...Your car may still start from cold with this system not operating correctly but stuck in the situation where it is enriching the mixture, and in this situation it could be that your mixture could be overly rich when trying to re-start when hot and the extra fuel is not required but is now inhibiting a start..... But then that is nothing more than a possible theory so do not grab at it as being the answer..
Rather than waiting till the engine will not re-start.. with the engine still running and warmed up if the "choke" is stuck "on" the exhaust may be smoky and the tail pipes black and sooty.... providing a hint as to what the issue may be..?
A general outline of the fuel system I might expect to be fitted to your car is that each carb body has a float that operates on a hinge as the fuel fills the carb.. float bowl.. the float rises with the fuel level and when it arrives at the ideal fuel level for carb operation, the float contacts and closes the valve supplying fuel to that carburettor, avoiding over filling the carb and overly richening the mixture or at worst spilling excess fuel out of the overflow.... As the fuel pump is obviously running to supply fuel for this process, with the float having reached the required level and the valve having shut off the fuel to the carb, the pressure will rise in the fuel line between the fuel pump output connection and the carburettors, at which point the fuel pump`s internal pressure sensing mechanism will cut the electrical circuit to the pump/ or operate a mechanical system to stop pumping, dependant on which type of pump is fitted..... until the engine uses up a measure of fuel in the float bowl at which stage the float drops and opens the valve, the pressure in the line drops, the pump switches back on, and the cycle continues...
In a situation where the float or the valve fails to shut off fuel to the carburettor there is an overflow system that generally dumps the excess fuel on to the road away from exhaust systems and the likes, such a situation could create a possible non start situation caused by overly rich air/fuel mixture, the smell of fuel could indicate such a possibility...? Looking under the engine may also provide some clue...Though I have no memory of the actual overflow system fitted to early 911`s, but I did once own a late 60`s 912.
My thinking behind the simple introduction of the easy start was to determine if you had a fuel issue or not.... But strange as it may seem engines can become hooked on that stuff, thus my suggestion was to use it as a one time test, and not as an alternative to a proper repair process, should your engine have re-started.
If as it seems you do not have a grasp of fuel system basics, then I suspect the very wise Mr DeMort`s suggestion would be the safest option for you, for I suspect it might even be too much to expect the average garage "mechanic" today to be up to speed with triple downdraught carbs..Though if there is a classic car specialist in your area that might be the next best bet if no Porsche specific mechanical skills are to be found locally..
While I understand so much information is available on the interweb it might still be worthwhile to try to obtain the Haynes Porsche 911 owners workshop manual No 264 in the Haynes series. Covering models from 2.0L through to 3.2L ISBN 1 85010 243 0 Which may not provide the answer to your issues, it may at least give you further insight to the nuts and bolts of your 911...?
Hope this helps in some way Riisu. :?:
