Glow plug light on ,limp mode , epic fuel pump.

[kangoo michael]

Hi i have a 2001 1.9 D55 kangoo with the epic fuel pump.
It runs and drives ok but when you go into engine over run it goes into llimp mode and the glow plug comes on, i can stop and restart engine and the fault is gone or turn the ignition and on again while still moving and the light goes off and normal revs are restored ,you can drive for miles as long as you dont allow the engine to go into over run , when you get to say a junction i dip the clutch and fool the engine , there is no faults stored ,i had a check and it showed a pump fault, i have a spare pump but would rather change a bit rather than the whole pump,colud it be a solenoid or a acuator .
It ticks over fine and rev ok , any help i would be grateful