The sending unit on my 2005 Trailblazer is shot, I've tried the Chevron trick and all, the light is still on so I know it's about time to change the pump.

My thing is this though, two days ago the vehichle started to shudder when I came to a stop, then again today it did the same thing. When I did the ride the brake and gas at a stop light it stayed running, but when I slowed to make a turn it stalled out. After restarting the problem went away...for now I guess but the check engine light came on.

Is this a sign the pump is on its way out or is there another issue because I know the fuel filter itself is internal on this model.

 

You need to have the SES codes read before anybody can guess at what the problem might be. AutoZone or Advance Auto will do it for free.

 

Bank 1 Sensor 1 O2 sensor was the code

Question, I know this is before the cat converter but the guy at Advanced said there may be 4 O2 sensors on this vehicle. Is he right or has he lost his mind, and if he's right which one is sensor 1.

Thanks for any input

 

I am assuming that you have the 4200 I6 engine. If that is the case, the guy at Advanced does not know what he is talking about. There are only two O2 sensors in this configuration. The B1S1 sensor is located IN the exhaust manifold.

You should also check over the exhaust manifold for cracks. I have seen a number of these crack causing a leak which can influence the O2 sensor negatively.

As far as the stalling goes, I would remove the throttle body and give it a thorough cleaning. These engines use an electronic throttle body and no IAC (idle air control) valve. When the throttle body gets dirty, the throttle blade can stick causing erratic idle.

I would clean the throttle body first, inspect the exhaust manifold second, then clear the codes and see how things go. If the code comes back, then replace the O2 sensor.

 

When you say B1 S1 code,is it a performance code or a heater code.Whats the number?There are 5 codes that a S1 B1 sensor can set...If its an activity code,there is a software update for the PCM.There is alot of software updates for an 05 S/T...It wont cause stalling though...The level sender is available seperately.There is a code for that too.Most aftermarket scan tools dont see it.You need to use a tech 2...If there is a lean code too,the pump may have low pressure...
To clean the throttle body,you dont have to remove it.Hold the throttle plate open,spray top engine cleaner in it and use a toothbrush to clean the plate and the opening.A dirty throttle body will cause stalling.A bad O2 will not.It will run with it unplugged.As far as the cracked manifold thing,it could happen but is pretty rare.You would also have an exaust leak.

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