guys,my blazer start and idle fine,but when i rev it,it starts to misfire and sputters with a light black smoke from the exhaust.the inline fuel pump sounds a bit noisy which i replaced about a year ago which never gave me good performance on the car.can it be that my fuel pump is the problem again?can i put in 2 inline fuel pumps to enhance the performance?

 

first what year and type of blazer do you have? Second what type of fuel delivery system do you have? (TBI, CPI,)? Also have you done any work on it recently say like a tune up?

 

it's a '98 4.3 vortec,if i'm not mistaken it's the tbi.no tune ups or work done

 

Well it could be any number of things.

But first, what brand of fuel pump did you buy? If you buy anything other than AC Delco or Delphi for the fuel pump then you will be replacing it every 6 months to a year.

And no, adding another inline fuel pump wouldnt do anything, it would only be as good as the first one.

Before you drop the tank to change the fuel pump you will need to do a fuel pressure test. If you dont know how to do that then search on here for the thread, and then if you cant find it just ask.

 

it's a bosch inline pump part no:0580464070.

 

Hmmm...? never heard of one of those used in a blazer. Well for one, for fuel pumps ive never heard of Bosch being the best to begin with. You need to drop the tank and put in the right AC-Delco pump. Spend a little extra and get a good pump that wont go bad, like THIS one.

Well first before you do that i would do the fuel pressure test. i would be curious to see what kind of pressure that inline pump puts out. I highly doubt the pressure is ideal

 

Yep, you really need to do that pressure test. According to the bosch specification guide, that pump is flow-rated at 3 bar/45 psi.

http://www.bosch.com.au/content/lang.../fuelpumps.pdf
While that doesnt mean it wont maintain and operate at 60 PSI that blazers need, it does mean it's designed for a 40 psi system and it probably will not meet the minimum 75 psi static pressure test.
New Delphi built pumps typically static test at 100psi.

Note many other pumps in that sheet are flow rated at 5 bar/75 psi. If you have problems getting AC Delco or Delphi pump where oyu are, and cant pass the FP tests here, I suggest replacing that model with one of the 5 bar rated pumps. Make sure that you follow the install guide on there.. dirty fuel/clogged pickup sock is a killer. And if the original pump is still in there, some pumps do not support 'pull-through' well.