I`ve fitted a 96 940 lpt engine and box into my 83 240.

It`s been starting and running fine for the last few weeks until today.
When I turn the ignition on the fuel pumps run for a few seconds then stop, start the car and the fuel pumps start up. After about 3-4 mins the idle drops quickly and then stalls. Turn the ignition off then back on again and NO fuel pumps but if left for 3-4 mins with ignition switched off and restat the car the fuel pumps work but only for 3-4 mins then the car stalls with no fuel pumps. I`ve checked the white fuel pump relay and it is all ok it appears that something is timing out and shutting the fuel pumps/relay off. According to the wiring diagram the ecu grounds the fuel pump side of the relay so I`ve tried another ecu and the same thing happens.

Does anyone have any ideas ?

Thanks Rob