blazer has 245k miles. problems started happening a few months ago when fuel pump went bad and i had that replaced and a month or so later i started getting the hesitation when accelerating the mechanic thought it could the cap/roters/wires/plugs or fuel filter so i got a full tune up and replaced the fuel filter and now some days itll hesitate when accelerating or idle really rough but for a week or so the check engine light didnt come on then finally the other day it did so i thought great now i can see what the problem is and i went to get the codes checked and it came back as a bad gas cap.....replaced the gas cap and im still having issues. it isnt a constant problem some days it will run perfectly fine(like yesterday) and today it is surging/hesitating/rough idle last thing i can think of is bad maf sensor. just looking for guidance for the next step before i just start replacing parts that dont need to be replaced

 

God yah, been there done that. Just remember it is normal for a bit of hesitation when a/c clutch system kicks in. the manual mentions this but all the rest of your issues are the same as many other chevy owners.


fuel pressure needs to be good, you replaced pump. engine tune up done with ac delco parts.


I high powered scan tool would tell you CaMSHAFT RETARD setting, this must be within spec.


make sure rotor was acdelco and cap were ac delco


aside of that I'm in same boat as you, not sure what next to check.


mine does all your doing and captain hook advised I need to check fuel/cam shaft retard. I don't have a tool to check it so I've just lived with it.

 

well its not a normal bit of hesitation lol im pretty sure everything was ac delco

 

What I've learned is if there is NO check engine light that is a glowing problem that can cause poor idle then you can be paying a mechanic to go on a mystery hunt. Hooking his scanner up, checking fuel trim which if it's below 7% it doesn't trigger a a MIL light. O2 sensor voltage i think can be checked. It can be hard to find.

My truck right now is pulling fuel away as i drive around, my longterm trim is 3.5% so it's running rich. Which I think could be trying to compensate for extra air then whats expected.

As parts where out I understand that compensating under 7% isn't necessarily a huge bad thing. If it isn't stalling really bad and causing a safety issue.

I've heard sometimes replacing the distributor itself often helps. Not sure why? The shaft maybe gets out of alignment? At 245KM I'd almost think "why not?"

Then again at that KM you could say that about a lot on that or any truck!

 

im going to give my mechanic a call tomorrow and see what he thinks the next plan of action should be. this blazer has been extremely reliable since ive had it only stranded my once luckily 1/2 mile away from my house when the fuel pump went bad but i got the car at 140k miles and 8 years later 105k more miles and maybe $1000-$1500 in repairs cant really complain. but i plan on driving it til the engine or tranny goes bad

 

it's the spider injector that I think can go bad and leak gas somewhere that ruins the engine, at least thats what one seller told me when his engine hit 301k. Keep me posted on what he thinks next step is please.

 

ok well talked to the one mechanic he wasnt sure where to look next with out a check engine light on and today on the way home the check engine light started blinking luckily i was 100yds away from my house. i got the codes checked and 2 codes came back p0303 which is cylinder 3 misfire and p0442 which is evaporative emission control system leak(small leak). i already got a full tune up and i checked and i dont think they are ac delco parts. so its either that or something else wont be able to talk to a mechanic til tomorrow

 

Could be the #3 injector. You don't know till some testing is done.

 

oh yeah when i pulled in after the light started blinking i smelled something burnt couldnt pinpoint where it was coming from

 

If you smelled something burnt and you have a misfire in cylinder 3, then take a good look at the number 3 spark plug wire, It may be in contact with the exhaust manifold.