How to check fuel pressure?

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.

what is fuel pressure settings .

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

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.

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

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.

Another quick question, could a deteriorating fuel pump cause a lean bank code p0171 or p0174? Thanks again.

what should the fuel pressure be?

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.

The low fuel pressure will definitely cause the 171, 174 codes.

They should go away when you install the new pump.

Roy

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

Gasoline KOER 28-45psi (2.0-3.2) KOEO 35-45psi (2.4-3.2

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

What should the fuel pressure be on a 4.6L engine?

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)

New to forum. That is a good quick answer. Thanks again

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.

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.

what is the specs of a 1995 f150 302 fuel pressure test

KOEO 35-45 psi

Thanks Doc I checked the pressure and it give me 28 key on only and the same on idol and when I give some gas it goes up to 35 and when I let go of the gas it goes under 28 to 26 and stays on 28 again.

Indicates a little weak is filter O.K.? if it runs good what is problem?

Well it stalls when driving to the point that it turns off hesitate to turn back on and when u give it gas. I have replace almost everything except the EGR changed the TPS and the IACV. The air flow master changed the fuel filter the plugs,wiring, the hole disturbing system and still no fix .

when i turn my key on i hear a hum sound coming from the gas tank. my truck used to start but it wouldnt until the sound stopped and now it wont start at all.

It sounds like the fuel pump is bad. I need you to check fuel pump pressure.

Here is a how to. Let me know what you find:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

If you need a gauge, most parts stores will lend or rent them.

Let me know.
Joe

Find Data Link Connector left rear engine comp> Hook up as shown in diagram and read MIL flashes. Post any codes

No engine light no code took it Ford and couldn't find anything gave it a body throttle cleaning but no luck . Let me go back to say that I had the head gasket replaced due to white smoke and from there it began check compression good. I can't remember what else.

Would remove EGR clean pintel and passage ways

Thanks Doc cleaned the EGR the pintel was stuck. It's still doing it do I need to run it around so that it gets stable . I will run it today see what it will do

Not sure driving will help but would be able to see if pintel gets stuck again

Ok did some driving and runs a little better but not quit . It stall when coming to a stop or turn on a corner . Hesitates a little when taking off but stables when I floor it .

Seems something to do with EGR may consider replacement. If lift up on diaphram at idle does engine kill?