My miggy has had cold start problem for the best part of this year... i have taken it to An Opel Dealer garage here and a Bosck Specialist with TECH II equipment and they came up with nothing. They both suggested i change the Injectors...which i did with used ones but it did not make a difference..cold start problem still persists. IT is not bad car always starts at third or fourth turning of key...then runs beautifully until after about 8 hours of not running(normally overnight).
I changed loads of parts till i got tired(crank sensor,MAF, coil pack,camshaft sensor,plugs...etc...etc ALL Genuine Vauxhall).
But none of them ever tested the fuel presssure. I took the car to a garage last week... he removed and tested the IN -TANK fuel pump...it works but there is no pressure. Fuel flows but with very little presssure. He reckons that is why i have been have been having the cold start issue. Is it Likely?

What is the best fuel pump i can buy (Vauxhall or Bosch)?