My truck won’t stay on!!

[ProvokedSavage]

I have a 2005 Silverado 1500 5.3 and it had a big misfire so I check the plugs they were all black kinda burned swap them all out then the truck would kinda start and turn off. My friend told me it could be the o2 sensor so I checked them out they where black as well. So my problem I replaced sparks plugs and sensors. I turn the truck on and it starts right up and turns off after like 15-20 secs and than it won’t turn on again. Plz help

 

Ps: the truck sat in one spot for like 2 or 3 months. And there’s no light engine on

 

 

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[txab]

For starter scan for codes

[ProvokedSavage]

For starter scan for codes

There’s non tho.


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[Doug_Scott]

I am not one that puts much into this, but, how old is the gas? 

 

O2 sensors are not even looked at on a cold start for at least a couple of minutes. They also would set a code. 

 

Have you looked at the fuel pressures?  Is the fuel filter external?  

[Colossus]

Unless they are heated O2 sensors.  Which many are.  Might be the fuel pump and/or fuel pressure regulator.  Both very common issues on the GMT-800s.  Have the plug wires and coils been replaced as well?  If not they are due.  What kind of plugs did you put in there?

[ProvokedSavage]

I honestly think it has to do something with either the fuel pump or regulator. And no the filter is inside the tank if I’m not wrong.


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[txab]

Then check pressure. Key on, engine off reading. 55-62 psi

[Doug_Scott]

30 minutes ago, Colossus said:

Unless they are heated O2 sensors.  Which many are.  Might be the fuel pump and/or fuel pressure regulator.  Both very common issues on the GMT-800s.  Have the plug wires and coils been replaced as well?  If not they are due.  What kind of plugs did you put in there?

Heated O2 sensors require time to heat up as well.  Trucks don't start up in closed loop.  That was my point. Besides that, an O2 sensor will not prevent the engine from running, the worst it will cause is limp home mode.  Never heard of an O2 sensor triggering walk home mode. 

[mjm-1957]

Is the security light on? If not take out the front O2 sensors and try starting it. The exhaust may be restricted such as a bad cat especially after stating you had a misfire before this all happened.

[Ferrnt]

I have an 03' 2500 Burban. I would lean towards your fuel pump(s). A few years ago, I too had the "stay running" issue with no light or codes. Checked pressure and it was fine. However refused to run. I have a 37 gal capacity fuel systems which mean I also found out I have two fuel tanks and two fuel pumps. Figuring the small fed the main I replaced the main tank and had the same issue. Finally replaced aft (or smaller) pump and she has run great since.

WARNING: Although I have an 03' Burban and purchased the correct fwd fuel pump, the aft fuel pump looked nothing like what I took out. Upon further investigation, my 03' was built later in the year which was when Chevy started putting the standard 04' pump in later 03's. Very difficult lesson. Don't know if you have access to a lift but let me tell you this, dropping and raising the tanks in the driveway is a pain. Regular gasoline weighs roughly about 6.5lbs per gallon. Where as diesel weighs about 7 lbs per gallon. I hope your tank(s) are close to empty. I can tell you how I did mine cause you cant drain big one from the from where you put it in.

Try and eliminate as much as you can before taking on the tank(s). I too did everything you did, troubleshot electrical, fuel rail plus more and ended up at the tank. Maybe someone from here that is an Auto Mech from Chevy has a better idea. I'm just a dumb aircraft mechanic (A&P).

Good Luck.

[jauldusmc]

Throttle body maybe if it kinda sputters as it's dying??

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[Supreme Pizza]

I would start the truck, and let it run until it dies. Crank for several seconds, then let it sit for a few 10 seconds. Cranks again, and let it sit. Make sure that it is NOT going to start.

 

 

No-start problems are generally pretty easy to diagnose. 

 

Is air getting into the motor? 

Is exhaust exiting the motor? 

Does it have spark? 

Does it have fuel? 

Does it have compression? 

Correct ignition timing? 

 

If all of the ingredients are there, then your engine runs. All you need to do is a process of elimination to find the missing ingredient. 

 

You compression and timing are probably fine. I would check the air filter and spark, then hit it with some starting fluid. You could also pull the upstream O2 out and then try to start it. 

 

[Doug_Scott]

The thread has been dead since June 1.  Pretty sure it either got fixed or sold by now. 

[txab]

Yep. Probably so. OP hasn't been back in two months

[ProvokedSavage]

Thanks everyone for the help. Found out it was a sensor on the back of the motor that was bad. Replaced it and back to normal. After I bought all the o2 sensor lol


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