How to check fuel pressure?

Tiny
JIMBOBM
  • MEMBER
  • 2010 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 11,000 MILES
Stalls after driving for a while. Codes P0171, p0131, p0150, p0172, p0174, p0175, p0300, p0456, p2195 and p2197.
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Thursday, June 25th, 2020 AT 11:12 AM

32 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Interestingly, most of the codes you listed contradict each other. However, I have a plan. The 171, 172, 174, and 175 all indicate both a lean and rich fuel mixture for both banks. That doesn't make sense. It should be one or the other. The 300 is likely caused by a fuel mixture issue and the 131 indicates a low voltage from bank 1 sensor 1. Now, the 2195 and 2197 are showing the oxygen sensors are stuck in the lean setting for both banks. So, I'm questioning if the rich codes were set first and now the vehicle is sticking in lean to compensate. Check out the diagrams (Below).

Here is where we need to start. I need to confirm fuel pressure. If the pressure is too high due to a faulty regulator, it will be dumping fuel causing this.

Here is a link that explains in general how it's checked:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the directions and specifications specific to your vehicle. The attached pics correlate with the directions.

Fuel Pressure T-Adapter 3/8"
310-D252 or equivalent

image WARNING: Do not smoke, carry lighted tobacco or have an open flame of any type when working on or near any fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

image WARNING: Before working on or disconnecting any of the fuel tubes or fuel system components, relieve the fuel system pressure to prevent accidental spraying of fuel. Fuel in the fuel system remains under high pressure, even when the engine is not running. Failure to follow this instruction may result in serious personal injury.

image WARNING: Do not carry personal electronic devices such as cell phones, pagers or audio equipment of any type when working on or near any fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

image WARNING: Always disconnect the battery ground cable at the battery when working on an evaporative emission (EVAP) system or fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

image WARNING: When handling fuel, always observe fuel handling precautions and be prepared in the event of fuel spillage. Spilled fuel may be ignited by hot vehicle components or other ignition sources. Failure to follow these instructions may result in serious personal injury.

If servicing a 4.6L (3V) engine, remove the Evaporative Emission (EVAP) purge valve bracket bolt and position the bracket aside.

If servicing a 5.4L (3V) engine, remove the air intake resonator assembly bolt and loosen the clamp. Rotate the resonator upward until it stops.

Remove the fuel pressure relief valve cap.

Install the Fuel Pressure Test Kit onto the fuel pressure relief valve.

NOTE: It may take more than one key cycle to pressurize the fuel system.

Cycle the ignition key to the on position and wait 3 seconds to pressurize the fuel system. Check for leaks before starting the engine.
Test the fuel system pressure to make sure it is within the specified range. For additional information, refer to Specifications in this section.
NOTE: 4.6L (2V) shown, 4.6L (3V) and 5.4L (3V) similar.

NOTE: Open the drain valve slowly to relieve the fuel system pressure. This may drain fuel from the system. Place the fuel in a suitable container.

Upon completion of the fuel system pressure test, open the drain valve on the Fuel Pressure Test Kit and relieve the fuel system pressure.

Install the pressure relief valve cap.
Tighten to 6 Nm (53 lb-in).

If servicing a 4.6L (3V) engine, position the EVAP purge valve into place and install the bracket bolt.
Tighten to 10 Nm (89 lb-in).

If servicing a 5.4L (3V) engine, rotate the air intake resonator assembly into position and install the bolt.
Tighten to 10 Nm (89 lb-in).

6.2L (2V) engine

Release the fuel system pressure. For additional information, refer to Fuel System Pressure Release in this section.
Disconnect the fuel tube quick connect coupling. For additional information, refer to Quick Connect Coupling in this section.
Install the Fuel Pressure T-Adapter 3/8" and Fuel Pressure Test Kit in line between the fuel supply line and fuel rail.

NOTE: The Fuel Pump Control Module (FPCM) electrical connector was disconnected during the fuel system pressure release and must be reconnected to complete the Fuel System Pressure Test.

Connect the Fuel Pump Control Module (FPCM) electrical connector.
Connect the battery ground cable. For additional information, refer to Section 414-01 .
NOTE: It may take more than one key cycle to pressurize the fuel system.

Cycle the ignition key and wait 3 seconds to pressurize the fuel system. Check for leaks before starting the engine.
Test the fuel system pressure to make sure it is within the specified range. For additional information, refer to Specifications in this section.
NOTE: Open the drain valve slowly to relieve the fuel system pressure. This may drain fuel from the system. Place the fuel in a suitable container.

Upon completion of the fuel system pressure test, open the drain valve on the Fuel Pressure Test Kit and relieve the fuel system pressure.
All engines

NOTE: It may take more than one key cycle to pressurize the fuel system.

Cycle the ignition key to the ON position and wait 3 seconds to pressurize the fuel system. Check for leaks before starting the engine.

Let me know what you find. Also, let me know if you have checked for vacuum leaks and if there is a leak at the exhaust manifolds on the engine.

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Monday, September 14th, 2020 AT 11:40 AM
Tiny
EUGENE TANNER
  • MEMBER
  • 2005 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
What is fuel pressure settings.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
DOCFIXIT
  • EXPERT
55 to 60 psi this guide can help as well

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

let us know
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
TRIEDITDONE
  • MEMBER
  • 2003 FORD F-150
  • 5.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 156,000 MILES
I recently bought a fuel pressure test at an auto parts store and when I hooked it up I was only getting about 17 psi when idle. Did a long term fuel pressure drop as well, but the pressure remains for a good 8-10 hours but does drop overnight. Another odd thing is when key is set to on but not starting, the pressure barely climbs any psi (only about 1-2 psi). Starting to think that the fuel pump is going bad, also I bought a new fuel filter because it s about time to replace it as well. Just want to know any suggestions on this matter. This was a solution I was looking into for my truck hesitating while starting. What I mean by hesitation is the truck will start, but sometimes it will take 4-8 seconds.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good evening,

You need a fuel pump. You confirmed your self with the pressure test. That is also the reason for the delayed starting as well.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

I would replace the filter as well when you do the pump.

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Roy
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
TRIEDITDONE
  • MEMBER
Thanks a lot for the reply. I think I m going to get right to it tomorrow go grab the parts and see what I can do hoping it doesn t rain. I ll post a update and see if it fixes the problem. Thanks again you guys are great.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
TRIEDITDONE
  • MEMBER
Another quick question, could a deteriorating fuel pump cause a lean bank code p0171 or p0174? Thanks again.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
JJT317
  • MEMBER
  • 2003 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
What should the fuel pressure be?
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
DAVE H
  • MEMBER
Fuel pressure ...4.2L & 4.6L.......Psi 30-45 ....Kpa(207-310) here is a guide to elp you test it.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Please let us know if you need anything else to get the problem fixed.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
The low fuel pressure will definitely cause the 171, 174 codes.

They should go away when you install the new pump.

Roy
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
BRUCEAFARRIS
  • MEMBER
  • 2002 FORD F-150
  • 79,000 MILES
Changed fuel filter about 50 percent pluged up tested fuel presure at 31 and holding seems low to me but dont know the specs for fuel presure
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
2CEXPT
  • MEMBER
Gasoline KOER 28-45psi (2.0-3.2) KOEO 35-45psi (2.4-3.2
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
KASEKENNY1
  • EXPERT
That is on the low side but not bad. If the filter was clogged then that contamination may have damaged the pump. If you don't have any issues currently I would let this pump alone but make plans on changing it in the future.

Here is a guide that will help with checking the fuel pressure in case you or others need that.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, I attached the info from the manual on fuel pressure. Please let us know if you have other questions. Thanks
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
ED4EDWAEDS
  • MEMBER
  • 2001 FORD F-150
What should the fuel pressure be on a 4.6L engine?
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
2CEXPT
  • MEMBER
2001 Ford Truck F 150 2WD Pickup V8-4.6L SOHC VIN W
Fuel Pressure
Key on, engine off 240-310 kPa (35-45 psi)
Engine running 193-345 kPa (28-50 psi)
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
ED4EDWAEDS
  • MEMBER
New to forum. That is a good quick answer. Thanks again
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
SGARBEL
  • MEMBER
  • 1997 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 147,000 MILES
Can anyone tell what the fuel pressure should be on my pickup. My Haynes repair manual says the OK pressure for 5.4L in on position should be 55psi and running is 55psi.I called autozone and they said it should be 30 to 45psi. I have tried researching on line to determine what the correct pressure should be. No luck.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
WRENCHER1
  • MEMBER
Here are the official specs

FUEL PRESSURE
Key On, Engine Off (KOEO) 30-45 psi
Key On, Engine Running (KOER) 27-42 psi

This is tested at the service port without blocking the return line.
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
TIGER
  • MEMBER
  • 1995 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
What is the specs of a 1995 f150 302 fuel pressure test
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)
Tiny
DOCFIXIT
  • EXPERT
KOEO 35-45 psi
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Saturday, May 29th, 2021 AT 10:35 AM (Merged)

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