92 skylark wont start intermittantly

my 92 3.3 skylark has began having problems i changed the rear brakes and now it will crank but wont start intermittantly . I looked up troubleshooting in the book and on the internet and at first I thought it might have been the crankshaft sensor so I did the test to see if the injectors had power and I got voltage on both wires I also checked for loose connections every where and found none. are there any other checks i can do without have a diagnostic computer. I bought a gm test code reader and it shows no problems just 1-2