ok my mom has a 2003 chevy trailblazer with a strait 6cl in it. it also has 50k on it.
lately when she goes to start it (when she leaves work after it has been in the sun all day) it won't start. it will crank but not start. and some times it will back fire when it dose start.
after she dose get it started it runs fine. it has had the fule filter replaced twice. the last time was about a week ago after the problems started.
the dealer just replaced some modual (somthing to do with the power locks, and some other componets to the electrical system.) it was about $300 i think. i have the old one sitting in my room still. the dealer also did a pressure test for the fule, and sead it was fine. the car has a fairly new k&n filter. the only thing i still need to check is the spark plugs and wires, no one can remember if they have ever been replaced, but i can't beleave that the dealership would overlook them. that would be the simplest solution

any help would be apreacteated. she wants to keep the trailblazer since it has been a good car, and it is almost paied off. she has turned to me to fix it, since the dealer ship as usual did not find anything wrong. they said the same thing about the door locks randomly locking with the keys still in the ignition.

 

no one has any ideas?

 

Welcome!

Is the Check Engine Light on? If it is, have the codes read at your local Autozone or Advanced Auto and let us know what it states.

These trucks are very sensitive to fuel filter restrictions.

I would recommend that you remove and clean the throttle body as well as check your spark plugs. To clean the throttle body, remove the intake resonator box from the top of the engine, disconnect the vacuum line and electrical connection from the throttle body, then remove the 4 bolts holding the throttle body to the intake manifold. Clean the throttle body with some sensor safe throttle body cleaner and reinstall. Do not worry about the fact that the throttle blade doesn't go all the way closed. That is its typical park position when the vehicle is off.

Your engine does not have spark plug wires. It is a COP (coil on plug) design. To check the plugs, you will need to remove the intake resonator box from the top of the engine, disconnect the six electric plugs on each of the coils, remove the coil retention bolt and finally remove the coil. I find it easiest to have a locking extension and a sparkplug socket to remove the plugs from these engines. This allows you to safely reinstall the plug without damaging it on the way down through the valve cover tubes.

Beyond that, I would need to hook up my scan tool to run through more tests. So unless you have a scan tool with bi-directional controls, I can't help ya there...

Oh and PLEASE be patient... As I was typing my reply your impatience got the better of you... Please familiarize yourself with the rules of the forum. Please do not bump a post after only 3.5 hours.

 

i will try to do what you said tommorow, and see if that works.
thanks.

 

Another thing came to mind...

How does the truck run once it's started? Does it feel powerful at higher rpms? These trucks have a tendancy to over fuel, killing the catalytic converter. It is possible that you have the beginning of a faulty O2 sensor, but again, the proper diagnosis of a faulty or failing O2 sensor would have to be done by looking at the sensor output to the PCM with an appropriate scantool.

 

my mom took it to a difrent shop.
i changed the spark plugs, and cleaned the throttle body, but that diden't work.
the truck runs fine after it is started. maybe the shop will find a bad o2 sensor.
i will keep you updated.

 

I'm curious as well, my 1994 S-10 4.3 does the same thing. If it has been sitting for a long time, it will start right away. If I have been running it and I stop for say 45 minutes to one hour, it will crank for a while to where I have to use the gas peddle to get it started. Here is the kicker, it will run fine one it has started, drive good , idle good!! I was dumb founded by the snag, no codes either. Someone had mentioned a possible leaky injector?