2001 Sport Trac too lean codes - help needed

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Apr 24, 2016 | 10:45 AM

Walston

Thread Starter

Cargo Master

Joined: Aug 2004

Posts: 2,575

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From: Greenville, SC

2001 Sport Trac too lean codes - help needed

Working on my son's 2001 sport trac. 200K miles but it has always been a great running truck.

I have two CEL codes:

P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)

I have found several issues so far, but have yet to get rid of these pesky codes.

So far I have changed:

Intake Gasket - I had coolant loss which replacing this gasket fixed.

PCV Valve and Hose - valve was damaged and the hose leaked.

EGR Valve - Valve was leaking

Fuel Filter

Mass Airflow Sensor

The engine does appear to be running much smoother now, but the lean codes remain.

Any ideas?

Thanks for the help!

Apr 24, 2016 | 07:02 PM

Walston

Thread Starter

Cargo Master

Joined: Aug 2004

Posts: 2,575

Likes: 36

From: Greenville, SC

Looks like it may be the fuel pump. 20 psi with just the key on and 39 psi running, from what I can tell, it should be around 65 psi. Anyone know for sure?

Apr 25, 2016 | 07:50 AM

shorod

Logistics Pro

Joined: Jun 2009

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From: Cedar Rapids, IA

Per the factory service manual, specification for fuel pressure is 60-65 psi for both KOEO and KOER.

-Rod

Apr 25, 2016 | 08:29 PM

steve(ill)

Hotshot

Joined: Jul 2005

Posts: 11,933

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some trucks have a pressure regulator on fuel line behind the injectors that dumps excess pressure back to the fuel tank.... possibly by firewall by brake booster. If you have one, make sure it is not stuck open or leaking off pressure.

Apr 29, 2016 | 08:50 PM

Walston

Thread Starter

Cargo Master

Joined: Aug 2004

Posts: 2,575

Likes: 36

From: Greenville, SC

I replaced the pump assembly in the tank. The pressure control valve was also in the tank. Pressure now is 63 PSI and the codes are gone. BTW, I removed the bed first and it made removing the tank to replace the pump MUCH easier. Runs better than it has in years.

Apr 29, 2016 | 09:48 PM

shorod

Logistics Pro

Joined: Jun 2009

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From: Cedar Rapids, IA

Cool, hopefully that takes care of the issue.

-Rod

May 13, 2016 | 06:40 PM

n5mj

5th Wheeling

Joined: May 2000

Posts: 29

Likes: 0

From: Eddy county, New Mexico

in-tank fuel pump regulator

Mine failed in the opposite way - the regulator gummed up - I blame the ethanol in the gas - leaving the fuel pressure mighty high. So high, gas started to leak around the fuel line connectors.

Never threw a code - just seemed to run rich, rough lumpy idle, a little gutless, but nothing unexpected for a 13 year old truck.

Changed the fuel pump assy - getting a new regulator in the process - and it runs like new.

Cheers,
N5MJ