2002 Chevy S-10 truck starts runs for a couple of seconds a

I bought the s-10 a couple of months ago was told it needed a fuel pump so I replaced the pump and now it will run for a couple of seconds and then it just quits I suspect it may have somthing to do with the security system the security light on the instrument panel occasionally flashes 3 slow flashes followed by 2 fast flashes I live in corona ca. I would greatly appriciate any advice on what to try or a place local to fix this thanks