Diesel input pipe

[jacaranda]

The diesel input pipe on my transit custom has a valve on the end ,with a 4 pin connector fitted ...what is the valve for as my transit doesnt start very well at all ,if i remove the connector so no power or anything going to valve its starts first time.I then put connector back on and engine ticks over fine and runs well and no probs .it just wont start with the power connected ..