Thanks very much K and GrumpyPa and Paul F and sewin for your generous time, and your amazing input.
Sadly I am only a structiral engineer, and must have missed the lessons regarding mechanical issues with motors
and therefore it has been a steep learning curve (still at ground level )
However my logical mind thought that the fact the tacho drops to 0 rpm as soon as the engine cuts out would suggest it is not a fuel or air problem. I assume fuel or air would cause the engine to splutter but would not immediately cause the coil to unpower the tacho ?
I will pass on your comments and suggestions to our local mechanic (son of owener who is away until May), which will add to his knowledge base, and hopefully find the fault.
Thanks again everyone, Barney
