P1153 insufficient switching bank 2 sensor 1

[RyleeBoh]

I have a 1996 gmc k1500, 5.0. It runs good other than sometimes, typically in cooler weather she starts to stumble from a stop and eventually when it is really cold out she stalls when I put it in gear. I have a p1153 code and some 02 sensor codes but that is it. I know its not a MAF because I swapped with my buddies and his truck ran perfect. Im suspecting fuel pressure, she has been through 2 fuel pumps in the last 8 months though too. Im kinda lost as too what it is at this point. It is very inconsistent at times. I also do have a lean running condition code as well, p0171. I don’t think its a leaky injector because she gets damn near 16mpg in town, Which is pretty good for these old girls.

 

[GoToGuy]

The forward/ front, no .1 , O2 sensor is what sends data to the ECM to aid in fuel mixture A/F ratio. The Aft/ rear. no.2 sensor is to monitor cat health ( 96 and up ) tighter emissions control in OBD 2. Do fuel pressure check , eliminate suspects.

 

[RyleeBoh]

The forward/ front, no .1 , O2 sensor is what sends data to the ECM to aid in fuel mixture A/F ratio. The Aft/ rear. no.2 sensor is to monitor cat health ( 96 and up ) tighter emissions control in OBD 2. Do fuel pressure check , eliminate suspects.

I just tested the pressure it was idling at 50 psi, my Chilton book says they should have 60-66psi. Now I am wondering why its low.

 

[GoToGuy]

In the engine sticky above are free FSM pdf to download. Really nothing beats the factory for a specific year which are available here. The diagnostic are written by the factory.
Poor electrical , low volts drop, bad ground, internal leaks, filter, collapsed rubber line, TB regulator weak spring bypass.
Eliminate suspects, find the faulty item. Don't guess, go with facts, it's not unknown to have offshore crap pumps, short life.

 

[RyleeBoh]

In the engine sticky above are free FSM pdf to download. Really nothing beats the factory for a specific year which are available here. The diagnostic are written by the factory.
Poor electrical , low volts drop, bad ground, internal leaks, filter, collapsed rubber line, TB regulator weak spring bypass.
Eliminate suspects, find the faulty item. Don't guess, go with facts, it's not unknown to have offshore crap pumps, short life.

I will look into it, Thanks.

 

[Nad_Yvalhosert]

I have a 1996 gmc k1500, 5.0. It runs good other than sometimes, typically in cooler weather she starts to stumble from a stop and eventually when it is really cold out she stalls when I put it in gear. I have a p1153 code and some 02 sensor codes but that is it. I know its not a MAF because I swapped with my buddies and his truck ran perfect. Im suspecting fuel pressure, she has been through 2 fuel pumps in the last 8 months though too. Im kinda lost as too what it is at this point. It is very inconsistent at times. I also do have a lean running condition code as well, p0171. I don’t think its a leaky injector because she gets damn near 16mpg in town, Which is pretty good for these old girls.

Your title states code P1153. Insufficient switching between rich and lean only on bank 2, not both banks. That's a clue...
Do you have P1154 (bank 1) also?
A defective fuel pump would affect both banks equally. Don't suspect fuel pump yet.

Your text explanation states P0171. That's a lean condition on bank 1. Do you have P0174 also (lean bank 2)?

I would replace both upstream O2 sensors before parts cannoning a third fuel pump.
I would however throw a fuel filter at it...

 

[Schurkey]

1996 gmc k1500, 5.0.

typically in cooler weather she starts to stumble from a stop and eventually when it is really cold out she stalls when I put it in gear.

Connect a scan tool, verify EVERY sensor and computer output. Check fuel trims, look at misfire counts.

How old are the usual tune-up parts and procedures? Vortec engines are known for distributor cap problems.

I have a p1153 code and some 02 sensor codes but that is it.

Define "some" O2 sensor codes. Don't tease us by listing one code when you have multiple codes!

Im suspecting fuel pressure, she has been through 2 fuel pumps in the last 8 months though too.

So check fuel pressure at prime, idle, and under load.

I also do have a lean running condition code as well, p0171. I don’t think its a leaky injector because she gets damn near 16mpg in town

A lean code is unlikely to be caused by a leaking injector. OTOH, lean codes are often caused by ancient O2 sensors; and by misfire. So again you need to look at misfire counts.

I just tested the pressure it was idling at 50 psi, my Chilton book says they should have 60-66psi. Now I am wondering why its low.

Prime pressure may require more than one prime cycle; and should be 60-ish. Idle pressure will be "less" but GM does not give a spec. 50--52 is common based on other reports on this site. Fuel pressure under load goes back up.

 

[RyleeBoh]

Connect a scan tool, verify EVERY sensor and computer output. Check fuel trims, look at misfire counts.

How old are the usual tune-up parts and procedures? Vortec engines are known for distributor cap problems.


Define "some" O2 sensor codes. Don't tease us by listing one code when you have multiple codes!


So check fuel pressure at prime, idle, and under load.


A lean code is unlikely to be caused by a leaking injector. OTOH, lean codes are often caused by ancient O2 sensors; and by misfire. So again you need to look at misfire counts.


Prime pressure may require more than one prime cycle; and should be 60-ish. Idle pressure will be "less" but GM does not give a spec. 50--52 is common based on other reports on this site. Fuel pressure under load goes back up.

I just did a pressure test with, key on, idle, wot. My pressures were 60,50,60. With the key on pressure it would drop to about 50 in a few seconds and hang for a little bit.

 

[Schurkey]

I just did a pressure test with, key on, idle, wot. My pressures were 60,50,60.

Reasonable, assuming your pressure gauge is accurate.

With the key on pressure it would drop to about 50 in a few seconds and hang for a little bit.

Seems like the pressure is reducing kinda fast.

 

[RyleeBoh]

Reasonable, assuming your pressure gauge is accurate.


Seems like the pressure is reducing kinda fast.

Im thinking its a fuel pressure regulator. At wot, it would jump to 60 then drop soon after down to 50. This was at 4k rpm for about 5 seconds each time we tested it.