Fuel pump turn on sometimes but not all the time.
 

i have a 99 s10 blazer. I just replaced the fuel pump less than 6 months ago and when I first replaced it started really hard. Now i can hear the fuel pump prime but it dosnt prime all the time. Could it be a ground problem?

Were did you buy the pump? I bought one about 8 months ago and mine is doing the same thing but will not start sometimes, I have the move the key on and of a few times before it will start. Mine is a 1999 as well.

Could be a poor/loose connection for most anything in the fuel pump circuit from the PCM to the pump, and the pump ground. Could even be a faulty pump. Have to start by checking voltage at the pump and work your way forward. Then check resistance on the pump ground wire.

I was thinking maybe a fuel filter. I got it to start up but it would keep bogging down. the fuel filter might be completely clogged. I just need to see how bad the filter is. It would be a lot better than replacing the fuel pump again. Anyone know of any tricks to get the fuel filter off? I know its kinda tough on this blazer.

The line usually rusts to the fitting, and if you turn the fitting, the line crumbles and leaks.

13mm socket and short extension removes the bolt on the plastic bracket that goes around the filter. Carefully pop the lines out of the bracket. A 16mm line wrench holds the fitting still on the fuel line. Use a 20mm open end wrench to unscrew the filter from the fitting.

Have you checked fuel pressure and leakdown? If so, what are the numbers?

Ok i changed the fuel filter and it is still starting really hard have to crank it over about 4 times to get it to start. When it starts it itles smooth. any ideas?

The pump is an AC Delco pump that I bought online

Instead of cranking try just tuning the key to the on then to the off position a few times then try to start it, that works with mine so far but not sure for how long it will work. It seems to get worse the hotter it gets out side. Hope this helps some