PROBLEM now 98 blazer 4.3 v6 just replaced fuel pump

i just replaced the fuel pump n my blazer. when i was dropping the tank i broke the stem off the tank vent valve so i bored out the hole n made a new stem for the valve lol. ok i started my blazer n now it runs rough and dies it also has black smoke coming out the tail pipe. i also forgot 2 change the fuel filter. what is the problem anyone please help could it b the valve or filter. i do have a filter now n waiting on the valve but i dont think thats the problem but idk thats why im askin

i just replaced the fuel pump n my blazer. when i was dropping the tank i broke the stem off the tank vent valve so i bored out the hole n made a new stem for the valve lol. ok i started my blazer n now it runs rough and dies it also has black smoke coming out the tail pipe. i also forgot 2 change the fuel filter. what is the problem anyone please help could it b the valve or filter. i do have a filter now n waiting on the valve but i dont think thats the problem but idk thats why im askin

Welcome to AF.
What engine and mileage?
Why was fuel pump replaced?
What was it doing before fuel pump replace?
Any stored codes?
Start with a fuel pressure test.
Watch for any fast leak downs.

New does not always mean good.
What brand of duel pump?

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

ok it has the 4.3l 262cid v6mfi n it has 200,000+. i replaced the fuel pump because it went out n i replaced it with a carter fuel pump #p74789. up untill the other morning when it stopped it had been running just fine but, the day before it didnt wannna start right up it would take 4 to 6 sec of it turning over before it would start i could kill it n it would fire right back up but after it had sat for 15min wouldnt start right up well i let it sit again n instead of cranking it i turned the key on till the fuel pump shut off n then it would fire up. so all that it what led me 2 believe it was the pump.

Check fuel pressure and leakdown, you'll find the problem. As MT mentioned, "New does not always mean good." That's why they have warranties. Does your parts store carry AC Delco or Delphi pumps? If not, find one that does. Unless you don't mind replacing the pump every time you turn around ;)

ok i will do that n thanx 4 the reply. i havent been able 2 get 2 the part store yet. lol. so i take it that carter isnt a good fuel pump? its got a 1yr warranty but really i dont wanna half 2 do all that again n less than a years time. i go 2 napa only cause i have an acct. there.

ok i will do that n thanx 4 the reply. i havent been able 2 get 2 the part store yet. lol. so i take it that carter isnt a good fuel pump? its got a 1yr warranty but really i dont wanna half 2 do all that again n less than a years time. i go 2 napa only cause i have an acct. there.

Napa should be able to get you a Delphi pump, after your Carter pump fails (in about 14 months, from my experience). I got my Delphi from Napa.

well i finally found the time to check it n the problem was a kinked return fuel line lol.

well i finally found the time to check it n the problem was a kinked return fuel line lol.

It's good news you found the problem, the bad news is you replaced your pump with a carter and not a ac delco as your going to be doing this job a couple months after your warranty runs out.... lol If you get lucky it'll go out before your warranty. Been there Done that sort of thing but we learn from experience.