2002 Avalanche -- Code 171 (Bank 1 Lean)

[dartmouthrocks]

Could really use help with 2002 Avalanche (5.3 Liter), 4WD. 99,500 Miles.
Driving great until yesterday. Died while driving about 30 mph. Lost power, may have regained briefly, then basically died. Barely able to idle. Cannot rev up. It was about 22 degrees out and thought that bad gas might have been part of the problem. Replaced fuel filter today (could not puff through). Barely idles for a few minutes. Not able to rev up. Error codes are 171 (too lean Bank one). Any ideas? Perhaps a bad fuel pump? Major vacuum leak? Anyone seen a code 171 with a bad fuel pump? (I agree -- strange no Bank 2 code). Any help much appreciated. (Got above freezing today and problem continued -- did add dry gas.)

[MT-2500]

Originally Posted by dartmouthrocks

Could really use help with 2002 Avalanche (5.3 Liter), 4WD. 99,500 Miles.
Driving great until yesterday. Died while driving about 30 mph. Lost power, may have regained briefly, then basically died. Barely able to idle. Cannot rev up. It was about 22 degrees out and thought that bad gas might have been part of the problem. Replaced fuel filter today (could not puff through). Barely idles for a few minutes. Not able to rev up. Error codes are 171 (too lean Bank one). Any ideas? Perhaps a bad fuel pump? Major vacuum leak? Anyone seen a code 171 with a bad fuel pump? (I agree -- strange no Bank 2 code). Any help much appreciated. (Got above freezing today and problem continued -- did add dry gas.)

I would check fuel pressure for up to specs.
02 sensors and vacuumn leaks and maf sensors can cause lean running codes to.
Also Clear code and see what comes back.

Post back fuel pressure readings.

[kenlwedel]

fuel pump pres.should be 60#to 65# if it is below 60 it will not start. if youturn ign.on &cant hear fuel pump run it is probley bad. have had same problem with 2002 avalanch, also with2000 escalade . good look

[dartmouthrocks]

Thanks for your response. Checked out an Actron pressure guage setup from AutoZone--

Checked fuel pressure at port and it topped off at about 12 psi. Must be the fuel pump unless someone has experience with a pressure regulator causing such a drop?

Mike

[dartmouthrocks]

Thanks--

Checked out pressure and it topped off at 12 psi.

Mike

[MT-2500]

Originally Posted by dartmouthrocks

Thanks for your response. Checked out an Actron pressure guage setup from AutoZone--

Checked fuel pressure at port and it topped off at about 12 psi. Must be the fuel pump unless someone has experience with a pressure regulator causing such a drop?

Mike

Where and how did it top off?
Jumper fuel pump and see what pressure goes to and how long it stays there.
Give us the fuel pressure with pump jumped?

Tank low on fuel or fuel filter pluged or fuel pressure regulator or even ground and hot wire to fuel pump can also lower pressure.

I like to plug or block off return line and check plump full pressure.

[dartmouthrocks]

Fuel filter is brand new. (post problem)

Vehicle has near new battery and turned over rapidly, spuddered (with couple of back fires) and did not start. Fuel pressure ranged from 10-12 psi. After 20 minutes -- psi remained at 5.

Would guess that the tank needs to be dropped to otherwise power the existing pump. (?)

Would appreciate info on how you recommend blocking off the return line to the tank if you still recommend that still being done. (plugged rubber line?)

thanks.

[dartmouthrocks]

(Tank is 1/4 full.)

[MT-2500]

Originally Posted by dartmouthrocks

Fuel filter is brand new. (post problem)

Vehicle has near new battery and turned over rapidly, spuddered (with couple of back fires) and did not start. Fuel pressure ranged from 10-12 psi. After 20 minutes -- psi remained at 5.

Would guess that the tank needs to be dropped to otherwise power the existing pump. (?)

Would appreciate info on how you recommend blocking off the return line to the tank if you still recommend that still being done. (plugged rubber line?)

thanks.

Always make sure on good 12 volt power and good ground to pump.
As to blocking return line a rubber line can be pinched off.
They make a special clamp tool for that so you do not damage line.
Or you can fabricate a plug for return.
Or go to fuel filter and disconnect line from tank and hook a gauge straight on the line from tank.
One other way to check full pressure is pressure at line to engine.
If pump is bad only replace with a Delphi oem type pump.
Airtex and other aftermarket pumps are junk.
Good luck and let us know how it goes.
Just do not run pump at full pressure 85-105 lbs over a second or 2.

[dartmouthrocks]

Thank you for the help. I checked the pressure from the pump after removing the fuel filter from the equation. It did not have sufficient pressure to empty gas from the tank (I was going to empty the tank into 5 gallon gas cans.) Not sure what happened to the previous 12 psi -- maybe the drop in pressure to nil was related to falling temps. Anyway, a new fuel pump solved the problem. Still somewhat surprised that the lean code only came in on Bank One. Did have trouble with the low temps fully removing the tank -- given the gas and return line being very stiff. Was able to accomplish the task by dropping the rear of the tank. Thanks again. (Post pump pressures in the mid-fifties.)

[MT-2500]

Originally Posted by dartmouthrocks

Thank you for the help. I checked the pressure from the pump after removing the fuel filter from the equation. It did not have sufficient pressure to empty gas from the tank (I was going to empty the tank into 5 gallon gas cans.) Not sure what happened to the previous 12 psi -- maybe the drop in pressure to nil was related to falling temps. Anyway, a new fuel pump solved the problem. Still somewhat surprised that the lean code only came in on Bank One. Did have trouble with the low temps fully removing the tank -- given the gas and return line being very stiff. Was able to accomplish the task by dropping the rear of the tank. Thanks again. (Post pump pressures in the mid-fifties.)

You are welcome.
And thanks for posting back how it went and the fix.

Fuel pressure should be a little orver mid 50 range.
Specs on V T U engines is 55/62.
Key on engine off should go 61-62.
Engine running at idle 57-58 range.
Engine under load on road should hit 60-62.
If pump pumping full pressure and regulator not holding pressure to specs you may have a weak or bad regulator.

Lot of fuel pressure regulators problems on 5.3 engines.

Check vacume hose to regulator for gas in it.
If so regulator is leaking/bad regulator.

Good Luck

[joeysz06]

i have an 02 silverado i notice i only get this code during low temps could it be the same problem? rough idle in cold starts rapid cylinder miss fire as well?

[MT-2500]

Originally Posted by joeysz06

i have an 02 silverado i notice i only get this code during low temps could it be the same problem? rough idle in cold starts rapid cylinder miss fire as well?

Welcome to AF on your first post.

Your answer could be yes or no.

Same engine?

What is mileage and your fuel pressure readings?

This post is over 2 years old.
Your best bet is to go and post in the silverado forum and give all informaton on your truck

[joeysz06]

Thank you