I am working on my neighbor's '98 Chevy Blazer. The blazer just quit running while she was driving. After the police officer pushed it out of the roadway she started it and it ran. The officer said she should have it towed so it came to me. I started it and it ran fine for two minutes and sputtered and quit. I attempted to connect my laptop; however, there is no ecu to be found. I checked the fuel pump relay and found with the relay unplugged there is exciter voltage and with the relay plugged in there is only .2 volts. I can apply voltage to the fuel pump and it does not work. If I wait a couple hours then the fuel pump will run fine for two minutes and shut off. Also, Every fifth cranking attempt there will be no spark either. I am not real familiar with Blazers or chevys, I work mostly on ambulances and fire trucks. I thought the ecu might be faulty since I thought it supplied the exciter voltage for the fuel pump. Installed another ecu and had the same results. Where should I go from here? I fix this blazer for her because she is elderly and her husband has passed. I need help with this one please. Thanking you in advance, Clyde