I have a 2000 blazer that runs rough when you first start it up.It hesitates when warming up. When it warms up it runs great. I have changed out the fuel filter, air filter, spider injector, spark plugs, rotor, plug wires, distributor cap and coolant temp sensor. I have also cleaned the Egr and maf sensor and still no luck. I have also fixed the vacum leak. Does anyone have any ideas?

 

What brand of parts did you use? I've heard these things only like ac delco parts. What about your fuel pressure, and have you replaced your O2 sensors?

 

I used napa parts and ac delco plugs. fuel pressure was 60 psi with key on and dropped to 52 psi after it was shut off for 15 minutes. I replaced one o2 sensor that was bad when i bought it. I forgot to mention its throwing a lean code.

 

pressure seems low, you may want to test it at the fuel filter. Captain Hook replied very useful information in my post about how to test it.

My blazer seems fine now after changing fuel pump. It was starting rough around 300-400 rpm in the morning and sometimes won't start.

 

On the way home on Friday it was running very rough and didn't want to move from a dead stop. I made it home shut the truck off and it wouldn't start back up. The pump makes no noise at all. What is a good pump brand to buy without breaking the bank?

 

Stick with ac delco or delphi if you want it to last any amount of time.