peugot 405 deisel,why wont it start after it has been left overnight unless i pump the deisel fuel by hand

sounds like the fuel pump might have gone think its under the rear seats on them can hear it ticking when the ignitions turned on but might have to get someone else to help if not proberly be the glow plugs

well if when you pump it by hand it works what electrical component do you think would do the work of your hand PUMP think about it you can get one for about 20 quid from a breakers not to hard to fit.

Sounds like air is leaking into the fuel system and causeing it to return to the tank.

Check the system (fuel lines from the tank to the pump) if nothing the seals in the pump may be gone. Try fitting a non return valve (cost about £6) to the fuel pipe thats feeding the pump,it should be marked on the filter housing .

A peugeot 405 diesel does not have an electric pump under the seats or anywhere else for that matter, the pump is mechanical & is driven by the cam belt.
You have got an air leak in the fuel line somewhere between the tank & the pump, chances r it is the diaphragm pump on the filter housing. The same one that u r using to start the car when it wont start, daft but true, the part peugeot fitted to assist fuel problems is by far the most likely thing to give u a fuel problem!
Fit a new filter housing & it will be fine.

fuel pressure loss, you may need a new fuel pump, get an electric one from a breakers.

l agree with Cedley 1969 its usually the diaphram that leaks air into the system when the car is stopped.replace it and you should cure the problem