hello everyone im a new member..but ive used this forum for good help before. well i have a 2000 blazer 4x4, 4.3v6. lately its been hard to start after it sits over nite. i thought it was the battery so i replaced it with a different one and same problem happens. engine cranks, i hear fuel pump start and have good psi at check point..i can keep cranking until battery dies, or until i hook up another battery to it, then it starts with no problem. while running i can see it recharges to 14v or so. i can start it up right away for a while, but once it sits over nite it will not start at all unless i hook it up to another battery. any help would be greatly appreciated thanks.

 

So.. it might be safe to say your battery wont hold a charge or it's discharging overnight.
to find if that's the case, buy a test light. One with bulb not LED and remove the neg terminal and put light between cable and battery with nothing turned on in the truck. If it glows more than dim, something is discharging it.
So oyu replaced it with another battery but it's not new either.

Take the car to a parts store and have the battery checked.

 

it does hold a charge and it does not discharge

 

What is the fuel pressure that you are getting? I had exactly the same problem with my 98. I thought that 45-50 PSI was good. I actually had to pour gas in the throttle body to get it started initially. Once it was started the engine would start immediately unless I let the truck sit until it had cooled off or over night. Make sure you get over 60 psi and it holds the pressure. Normal pressure is 65 psi. Just me experience.

 

i was getting from 55 to 60ish..i was thinking of replacing fuel filter tomorrow, i did oil change and spark plugs yesterday. it started fine for a while but once i went to work and let it sit for 3 hrs or so it did the same thing..keeps cranking but wont start. then it just started with no problem. this morning when i went outside to start it it wont..

 

Change the fuel filter first and if that does not work read below.

I just installed a brand new fuel pump assembly in my 2000 Blazer and the new pump with new filter only produced 60 psi. Have you put a fuel pressure gauge on the engine and once you have initial fuel pressure with the key on turn the key off and see if the pressure drops off slowly over time? Does the pressure drop while cranking the engine? If the pressure goes down I would seriously consider changing the fuel pressure regulator which is a heck of a lot cheaper than a fuel pump. That might be an idea for you since you are getting fairly good pressure now. I seriously doubt that it is the fuel pump if it is pushing 60psi.

Have you ever or know of anyone that changed the injectors in this engine? Does the truck when running run rough at idle or sluggish? The reason I ask is because you will have to dig into the intake that far just to change the pressure regulator, if you go that route, since it is part of the fuel spider (injector assembly) it might just be a good idea to just change the whole assembly and know that base is covered. It is an easy install but a bit more money of course. Just a thought.

 

Not a good test. If you start it by the book, the pressure will drop because the manifold has vacuum as the throttle plate is closed.
I'm thinking you should see the gauge flutter with every intake stroke, whatever that's worth.

If you crank it with pedal to the floor THEN it shouldnt drop.
But the PCM has ALSO reduced fuel flow because it thinks you want to clear a flooding condition.

 

cool cool cool, thanks for the info..but, i have no clue if any before me replaced the injectors, i seriously doubt it, and i meself have not replaced them..will change filter tomorrow and let ya guys know the results.

 

Pettyfrog made a good point about the MAF sensor possibly being dirty. Go to the link he provided. I usually use brake cleaner but they actually make a spray cleaner which is specifically named MAF sensor cleaner. It is available at most any auto parts store.

 

cleaned MAF sensor and it definitely worked better, changed fuel filter but nothing happened still not running but...i hooked pressure gauge again to see what was up an it was lower than before around 40-50, when i hook up another battery to jump i notice that the pressure jumps up to spec and it starts right away no problem..so safe to say pump is shot? hahaha