I have a 99 Blazer with a 4.3 v6 with 100,000+ miles. It would not start and assumed it was out of gas. Put in several gallons and it ran for a day, then it would not start again. I suspected the fuel pump finally wore out. I noticed that it does not prime itself for 2 seconds when you turn on the ignition.

I ran a hot wire from the battery to the fuel pump test terminal by the fuse box with the ignition on and nothing happens. I went ahead and put in a new fuel pump and the same thing happens. I also tried a new fuel relay swith (located in the fuse box) but still nothing happens.

One thing I noticed. When I turn on the ignition switch to see if the fuel pump is running, the tach needle jumps around and there are clicking noises coming from the fuel relay switch and what I think is the fuel meter (a small box next to the carb).

Any ideas, I'm stumped.