!997 C3500 No power great idle

[veprk130]

I just recently encountered a problem with my truck:

 

1997 C3500 CrewCab dually 7.4 vortec

 

One day is was running then the next it was not.

 

Engine has a hard start on cold, but when warm it idles evenly at 1000rpm.

Once I push the gas pedal it just bogs down with no power at all.

 

Here are the codes I found:

 

P0131 - O2 Sensor Circuit Low Voltage (bank 1 sensor 1)

P0150 - O2 Sensor Circuit Malfunction (bank 2 sensor 1)

P0151 - O2 Sensor Circuit Low Voltage (bank 2 sensor 1)

P0171 - System Too Lean (bank 1)

P0174 - System Too Lean (bank 2)

 

Any ideas would help. I was thinking replacing the 2 from O2 sensors.

 

Ruben

[sflichel]

Check your TPS, make sure its ok, then maybe move on to your MAP sensor and check it. Could also be a vacuum leak somewhere.

[veprk130]

Well thanks for the tip, but it did not work.

 

I replaced the following:

 

TPS - was broken

MAP

Idle control air value

 

Still runs the same.

[mmmikkke]

Did you check fuel pressure?

[veprk130]

No not yet. The fuel pump is a little over a year old.

[bobd54321]

check or change the fuel filter, It could be stopped up.

[ChevyTech007]

Unplug your MAF sensor so it goes into default. Drive and see if it helps. If it helps, replace the MAF sensor.

[veprk130]

Thanks to everyone and their responses.

 

It turns out it was the fuel sending unit. One of the tubes was loose and the base

of the connection. Once replaced all is good.

 

Ruben