i have a 99 tahoe that i have put all new stuf for the fuel pump,lines, and filter, but i still having a hard time starting it even on starting fluid, i put it on a hand held Snap-on Diagnostics scanner and it doesnt have any codes but when i go to check the injetors as soon as i try number one it stops running,,, any ideals what it might be? remind you im not very good with the Diagnostics scanner. thank you