I have a 1990 discovery petrol (carb) manual.
When it has been left awhile it takes a long time to start (10 sec or more) and I've come to the conclusion it's because the fuel pump is not running when the ignition is turned on. It seems to need the engine cranking (or the ignition switch turned to start). Once started no problem whatsoever and no problem restarting.
I've proved this to myself by priming the fuel system - connecting 12v to the fuel pump before starting having been left overnight - and it then pretty much starts on the button.
I need to find the fuel pump relay I think to troubleshoot further - but where is it??!!!
Better still, if anybody has had this problem and solved it...
Many thanks