I have a 1996 k11 micra  [bought it 4 years ago] and preparing for the worst, i ALSO bought a replacement engine with its ancillaries, gearbox ,ECU etc from a breakers .
When my micra developed similar problems to above ,ie engine cutting out 
 [after following the shortest route directions on my sat nav through rough terrain eventually coming to a halt in flooded inescapable tractor rutts and getting shoved/nudged  out by a passing  good samaritan with a landrover  at the expense of my tailgate ] 
I started to swap parts one by one [carburetta or whatever it is called ,temp sensors ,distributor , thermostats ,ecu,etc] even though it seemed self evidently  like a fuel starvation  problem with the engine  starting well then accelerating before cutting out after 5-30 seconds 
I tested the pressure of the fuel pump at a point just after the fuel filter[output] in the engine compartment, it indicated normal fuel pressure and the fuel pump in the fuel tank under the rear seats could be heard running/buzzing  two or three seconds after  the engine cut out , never the less I decided to remove and examine the fuel pump and pressure  test  it only  to find it perfect ,on reinstalling the pump, after what seemed to have been a pointless exercise i then noticed [it pays to be slow and observant] within  the flexible rubber fuel tank entry  return pipe  at about 1 inch from the end  a white sticky substance which turned out to feel and look like  chewing gum   I removed  it using a long screw whilst pinching the rubber in order not to push it further in 
Now my micra which had been getting increasingly  sluggish  before the final bumping through rutts pushed the gum allong the fuel return  line to block the tank entry spiggot causing it to become unroadworthy is whizzing along again 
Was the the gum deliberately used by a repair garage to create future work or was it bad work shop practice using gum to temporarily block a fuel line while conducting work on an engine ?
The car had been repaired by myself for four years only to be  out of my sight once when left in for mot welding three years ago.....hmmmmm
                
 will bort
                
 July 2012