Continuing fuel problems

[Mechcanico Lee]

Some thoughts ...

Before the fuel pump module was replaced would the car do the fault regularly or could it behave itself for along time ?
If it was playing up regularly it seems to much of a coincidence to behave for 3 weeks without faulting

You say after the fuel pump module was replaced all seemed well and you have had a good few miles done to confirm that it was good ?

What if either of the In tank pumps are pulling to much current and over loading the pump control module and when the pumps cool back down this allows the module to work correctly again .

I would be scoping the heavy wires to the In tank pumps and see what they are pulling out and the current ripple may show a bad armature .

Some of the bigger mercs albeit diesels that have stirrup type fuel tanks had an issue where one side of the tank would empty itself ..... this would cause the submerged pump to over heat and burn the relay contacts .

This fault was caused ultimately because the high pressure diesel pump was at fault and not returning enough fuel to one side of the tank .

As with any module failure you have to ask why has it failed ....,is there an underlying fault ??

Does the fuel control module vary the voltage to the in tank pumps as engine demand increases ?

From a diagnostic point of view I would be looking at fuel pressure .... compare to spec then when car faulted see what's happening to the pressure at that point .