806 TD 1997 won't start

Dear all

New on here and I have a common problem it seems......could I solicit some advise please?

I bought this car recently and it was running like a dream, I let the battery run flat, I charged it and after that could not start it even with the breakdown guy who suggested it may be electrical ? Could not jump it either under tow

Took it to an auto electrician who tested it and said its not electrical, the immobiliser is fine and suggested it may be either the ECU is at fault or the stop solenoid on the diesel fuel pump. diagnostic tool was no help either with this guy or the next mechanic, apparently its too old?

On another forum it was suggested the ECU would not be the culprit as it only does minor things with the EGR etc. and would not stop it from starting but if its faulty it would make the car run badly once it was running

Simply put, there IS FUEL getting to the fuel pump but NO FUEL past it and to the injectors

The previous owner and I got it running with a little patience and easy start about a week ago at the mechanics, as he could not get it going

Ran it for 10 mins and then tried it again....started first attempt

Left the car there leaving with smiles all round, however the mechanic tried to move it 15 mins later....no joy, would just not go

We have ruled out the glow plugs due to it being warm and still not starting, now we have been led to believe its the stop solenoid on the diesel pump

Two options here, change the pump and belt etc. or remove the armour on the pump and replace the solenoid

Can I get any opinions or previous experience please any however small would be greatly appreciated

The previous owner had intermittent starting problems, but only rarely, he got round it by a small squirt of easy start which he was advised was ok....I know, bad for the engine

Do you think it is the correct approach to start with the stop solenoid? and if so has anyone done it in situ??

Thank you...Tom