Engine will not stay running

We use a burnable brake cleaner (less chance of ruining parts) and yes you can drive the vehicle across the lot as long as you spray cleaner in it. Uses a lot of spray. But we got it on the hoist so we could change the fuel pump and then used it to drive off the rack to put it back out in the lot until we have a chance to work on it again.

Fuel pressure right on target numbers. Mass air flow sensor is reading 1.97 on start up even if it is or isn't plugged in. We are ordering a new one. Kind of weird that it doesn't give a code. But we have heard of this before with another Trailblazer.

It is working. Also brand new fuel pump was installed and still acts the same way. We are going to replace the mass air flow sensor, hope it works. We will let you know. The reason we replaced the fuel pump at first was because we thought that the pump might be losing power after start up. And/or lots of water/crud in the fuel tank. So we replaced and cleaned the tank. No water, no crud. Really clean tank. So we replaced the fuel pump and it still ran like it does. Runs for 5 seconds and then it chugs and shuts off. It's my daughters rig and it has to run good. I'm a retired mechanic and the shop I used to work at is fixing the Trailblazer.

Mass air flow sensor did the trick. We figured with the reading the same at 1.97 whether unplugged or plugged in when started. Had to be some thing not right. With the new one in it was reading 7.90 ish. And running like a top. The tank when we changed the fuel pump was clean as a whistle. It was not dirty, Just like I said. No crud in the tank. So, no codes and won't run after start up. Check the Mass air flow sensor. If the sensor reads the same if unplugged as it does when plugged in. Save some major cash and try replacing it first, before trying the fuel pump.