Car hesitates on 2005 Pontiac Montana

I just put a new fuel pump on my car.but when I go to start my car it still hasitate to start up.what could b wrong with it? my mechanic told me it could be some kind of security system once I putI put the key in the ignition wait until the security lights go off and start it that true?

Asked by for the 2005 Pontiac Montana
what is the fuel preesure and does it bleed off fast after eng is turned off. could be fuel pressure reg issue
1 more answer , 1 more comment
has mechanic checked ignition system? had simular problem, turn out to be alternator. review when last tuned up. could be a fuel issue also.
Okay thanks guy's. I just bought the car last week and having trouble with it already. I don't know when was the last time it had a tune-up.I thought if it was alternator that my lights Will b dull?