1997 Blazer won't start!

I have a 1997 blazer 4.3 vortec with 109,000 miles on it and vin W. Problem just started this winter. When the vehicle sits overnight, it has a tough time starting in the morning. It will continually crank and will almost fire, but jsut stumbles. After a few cranks, the engine fires and will start the rest of the day with on problems. It drives great until the next morning. I have checked the fuel pressure and I am getting 59 at key on and stays there. I recently did a full tune-up, new fuel filter, battery and ignition coil. It had a new fuel pump put in 20,000 miles ago with all new assembly. I had it at the shop, and they seem to think it is the injection unit. I have it narrowed down to a fuel problem, but cannot pin point it. I asked at Advanced Auto and Oreillys about it, and they both seemed to think if it were the injectors, it would be missing and not running well. I know that I should check for washing and such, but is that a hard job to take the plenum off or is it pretty easy? Also, are the injectors all seperate or is it one full unit? I think it is a CSFI unit and those are seperate aren't they? Thanks.

Yes the injectors are separate but are under the upper intake in a big black case.
First Have you checked the fuel filter?
Then.
You need to run a full fuel pressure check on it.
It requires 65-66 lbs of fuel pressure on a cold start.
59 is not quite enough. Even 2-3 lbs low will give a hard start cold.
Make sure your gauge is up to par and reading good.
Here is the guide lines on a fuel pressure check.
And it will let you know if fuel pump is weak or if fuel pressure regulator is leaking or bad.
Hard to start cold.
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.
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.
Post back fuel pressure readings.

Also, check the battery with a load type teste - AutoZone will do it free. Cold weather will zap a weak battery when it sits overnight. Without a fully charged battery you get the no-start that you've described.

It appears a lot of people are having starting problems in this cold weather.

Well my reading were 59 psi during the cold start mornings. The battery is brand new. It is also a bigger size so I can get more cranking amps. Over the weekend, it wouldn't start so I put a 200 amp boost on it and it fired right up. I don't know if my starter is dragging or something else isn't firing right. What would cause the car to start if the boost is on it? I am totally stumped. Thanks for the replies. I will get back any other info later in the week.

how are you attaching the jumper cables? could it be a top terminal battery? check for corrossion at cable ends at the post connectors. remove and clean, grease well with dielectric grease. it could be a bad connection and (hi resistance ie voltage drop) and when you clamp on the jump a good connection is made. have you checked the current draw? charging voltage, and battery voltage? how about the neg ground connection??

I am charging in on the top posts, but the connection are on the side of the battery. I have a problem with them last year and took and cleaned them and when I bought the new battery I cleaned them again. So I don't think that is my problem. Could a bad starter be it or maybe some other component? Thanks.

You need battery to turn the engine over good.
BUT
You need 6 more lbs of fuel pressure for the injectors to squirt on a cold start.
Even a couple of lbs low will give a hard start cold.
You need to get that fuel pressure up.
MT

When cranking, does it sound "slow and tierd" or does it crank on in a happy mood?
Hook up a DVM over the battery to check what voltage it leaves when cranking... But I can´t realy say if a low voltage would point to the battery or the starter... Anyone know what is the lowest voltage the ECM/PCM needs?

//F

What would cause the car to start if the boost is on it? I am totally stumped. . . .
You need to have the battery checked with a load type tester and also have the alternator output checked. It appears you have a weak battery, dirty cables or both. Dirty cables or a weak alternator will result in a weak battery. (Not necessarily a bad battery, but a weak one due to it receiving a low charge) You can't go on the assumption the battery has to be good, "because it's new" - you need to check it to make sure. With a weak battery or dirty cables the starter will draw all the current and not leave enough for the fuel pump to reach the magic 60-61+ psi for cold starts. (Been there, done that) I imagine once started with a 200 amp boost it started great the rest of the day, right??

"ditto" check the battery under load, battery ground, engine ground, all connectors at the battery. side terminal also need to be cleaned and greased w dielectric grease. make sure they are tight and the cables do not move. i ahve seen many a battery w "tight" connections that were loose. the side post termianals have grooved indents that need to be interlocked before tighting.