Please help diagnose truck problem!!!

[Momof2withachevy]

I have a 2001 Chevrolet Silverado 1500 with the 5.3L motor not to long ago it started having a problem to where it won't accelerate past 20mph even if the pedal is to the floor I have replaced the following:

-Oxygen Sensors(all 4)

-Spark Plugs

-Coil Packs

-Throttle Position Sensor

-Fresh oil change and filter

 

What else could possibly be wrong to make it not accelerate!  PLEASE HELP!!!!

[dsr611]

Fuel pump/fuel filter (can't remember if the 01 has an external fuel filter or if it's built into the pump)

[txab]

It does have an external fuel filter.

 

You should always check fuel pump performance before throwing parts at it.

 

Also the fuel pressure regulator under the hood

Edited December 25, 2020 by txab

[Black02Silverado]

Once you check the fuel pressure and change the fuel filter.  The next thing to check is the catalytic converters.  They could be clogged.

 

How many miles on the truck?  Does it burn/use oil?

[nfisherman]

On 12/23/2020 at 6:24 PM, Momof2withachevy said:

I have a 2001 Chevrolet Silverado 1500 with the 5.3L motor not to long ago it started having a problem to where it won't accelerate past 20mph even if the pedal is to the floor I have replaced the following:

-Oxygen Sensors(all 4)

-Spark Plugs

-Coil Packs

-Throttle Position Sensor

-Fresh oil change and filter

 

What else could possibly be wrong to make it not accelerate!  PLEASE HELP!!!!

You don't mention a Check Engine light. Is it on? Have you checked for any error codes? Those would give you a good idea of where to look.

[Momof2withachevy]

14 minutes ago, nfisherman said:

You don't mention a Check Engine light. Is it on? Have you checked for any error codes? Those would give you a good idea of where to look.

Yes check engine light is on and as soon as you try to drive it flashes

[nfisherman]

21 minutes ago, Momof2withachevy said:

Yes check engine light is on and as soon as you try to drive it flashes

A flashing check engine light means it's an urgent problem and you could damage the engine by continuing to drive. You should buy or borrow a code scanner and read the error code(s). That will at least give you an idea of what's wrong and what you need to buy/replace. 

[Momof2withachevy]

32 minutes ago, Momof2withachevy said:

Yes check engine light is on and as soon as you try to drive it flashes

The codes that come up are P0300 and P0449

[nfisherman]

21 minutes ago, Momof2withachevy said:

The codes that come up are P0300 and P0449

Here's a link for P0449:

https://www.700r4transmissionhq.com/p0449-chevy-silverado/

 

Here's one for P0300

https://www.700r4transmissionhq.com/p0300-gmc-sierra/

 

Oops. I just noticed this was in the as a GM technician forum. I'm not. I just read the message and thought I could help narrow it down. Feel free to ignore. Merry Christmas. 

 

 

 

 

Edited December 25, 2020 by nfisherman

[riverbanks]

More info the better,sounds like weak fuel pump,or the filter is plugged,and,what is a tech?I got vise grips,I think I'm qualified