99 Nissan Maxima No Start

[I_build]

Out of the blue she cranks but she wont start. The security light stays on steady while cranking. I called a mobile locksmith who said the key is fine and the imobilizer ring is fine but when he tried to reprogram he was unable to connect. He was able to connect using an OBDII reader but still told me I should look into replacing the ECU. Rather than do that I had the vehicle towed to Courtesy Nissan on Hillsborough Ave in Tampa. 100$ later they told me the fuel pump was the problem. I told them that everything I have read online about a steady security light indicates the security system is preventing the car from starting. They told me that when fuel was introduced to the system the car started. They assured me it was the fuel pump and quoted me 600$ for the repair. I asked them to give me that in writing. I took the car home and purchased and installed a new fuel pump. Low and behold I have the same problem. If I spay some starter fluid on the air filter and crank she will fire up briefly however she shuts right off and the security light is steadily lit.. Dose the security system cut spark? D