I have a 2001 blazer 4x4, with 203k miles. About 3 weeks ago, it started to hesitate when i started the engine, first start of the day (cold). After it starts and runs, it was fine. I've replaced all ignition parts (cap, rotor, wires, plugs, coil, ICM). I pulled the IAC valve, cleaned it and the bore inside. That changed the behavior a little bit, but it still hesitates with a cold start. Then this morning, on my way to work, a new symptom popped up in addition to the previous; it feels like it was trying to cut off while cruising around 55-60 mph, going up a slight hill. It did this about 3 times over a distance of 26 miles. I plan on replacing the IAC this weekend, and doing some more cleaning of the throttle assembly. I am getting no engine light while all of this is happening, so no codes. I should add that once the engine is warm, it runs and starts normally (except for the cutting off part, that just started today) if anyone can help point me in the right direction, I'd be a happy man.

 

Update...
I replaced the IAC valve and cleaned the throttle body out really good over the weekend, and of course I had to wait till morning when the engine was good and cold (engine cold, not weather cold), and I still have the same problem. After a couple of turns of the key, it finally sputters a bit, then smooths out. This is driving me nuts, and I'm out of ideas. Anyone out there have any ideas??

 

Have you checked your fuel pressure and, more specifically, the leak down rate after the pump shuts off?

 

I am going to be doing that anyway within the next couple days, i wanted to test it and make sure it was the pump before I plunk down the 300 for a new one. I see the ideal pressure should be around 60, 55 running.... with the key off, is it supposed to hold its pressure? i have the feeling i might see mine drop slowly.

 

I have a 2003 chevy blazer 4x4, with 140k miles. When I'm driving and reaching a speed of 50 to 55 mph my truck starts hesitating and if I go up a hill the engine lights comes on especially when I'm stepping on the gas cause I'm afraid the truck is going to shut off

 

have the codes read and tell us what it says

 

im looking into getting a 2000 blazer it has this problem too it is hesitant on cold start but after letting engine warm up it runs just fine I am also trying to find out if this isa major problem or something relatively cheap to fix

 

It could be lot's of stuff. Some cheap some expensive, unless it's a deal that's too good true.
Remember what they say about deals that are too good to be true.

Why start with one that already has a problem? There's a ton out there to pick from.
When you go to check these out, tell the person you want to look at it first thing in the morning with a cold engine.

Drive it to a place like autozone were they can put it on a scanner. They can tell if someone has just cleared the codes to turn off a check engine light. It will come up as test not complete or something to that effect.

 

so I decided to get the blazer in question there where no codes in the system. a theary I am having is could it possibly be the trans fluid and filter may need changed seems it pretty much runs fine after a short warm up but seems like it shifts slightly hard nothing horrible, just seems to stay in gear a lil long. I have noticed this question has been asked a few times in different places but I haven't seen any of the askers come back to say they found the problem and fixed it. tomorrow I am going to change oil and trans fluid in hopes to get some kind of good results and will keep everyone posted on my progress and will be all ways looking forward to all suggestions. thanks .

 

so far I have done oil, trans , fuel and air filters/fluids have slight change in the hesitation. So now im wondering do you guys think I will be better to go for fpr fuel pump spider or what next im sure that some one here can help.