Help needed- Fuel pressure test persistent p0174 - Toyota 4Runner Forum

earthrealm · 04-26-2019, 02:23 PM

So, have been digging around for some time now, no luck.

my truck has a persistent p0174 code - lean condition, i have cleaned the maf and TB, changed air filter, inspected for vacuum leaks, no dice.

am now suspecting the fuel pump/filter, but would want to test the fuel rail pressure before attempting to change the pump. bought the fuel pressure test kit off amazon, and have looked all over the engine bay, but i cannot locate the test port for to hook up the pressure test kit,
my LTFT bank 2 is 37%, while bank 1 is 18%
would be grateful if someone can direct me to a picture of video showing where or how to hook up the pressure test kit on a 2005 v6 4runner

waypoint · 04-27-2019, 11:17 AM

I haven't seen a video, but here's the shop manual procedure:

https://www.customtacos.com/tech.old...6ta/009000.pdf

2003-4x4runner · 05-04-2019, 02:09 PM

Have you tried replacing the gas cap yet? If not, you should. The rubber seal tends to crack over time. Buy OEM, the cheap ebay/amazon don't seal good.

81runner · 05-04-2019, 11:07 PM

there are two fuel lines near the brake master cylinder. Black cover is return, white cover is feed. You want feed. Those fuel trims being what they are, my recent experience with this makes me feel like your issues are related to the specific engine bank. If it were fuel pressure, I would think you would get lean codes for both engine Banks. Is your exhaust rich smelling?

earthrealm · 05-06-2019, 04:44 PM

Quote:

Originally Posted by 81runner

there are two fuel lines near the brake master cylinder. Black cover is return, white cover is feed. You want feed. Those fuel trims being what they are, my recent experience with this makes me feel like your issues are related to the specific engine bank. If it were fuel pressure, I would think you would get lean codes for both engine Banks. Is your exhaust rich smelling?

yeah, thanks seen the fuel lines, and unclipped it, yes, my exhaust smells rich at idle, and a p0430 - catalyst code pops up after a >50miles highway drive

below is my freeze frame data.

Freeze frame report generated by Torque for Android
================================================== =======

Vehicle VIN: JTEBUXXXXXXXXXXXXXX
Vehicle Manufacturer: Toyota
Vehicle Calibration ID: 33535000

Freeze frame information:
------------------
Fuel Trim Bank 1 Short Term = -1.562 %
Fuel Trim Bank 1 Long Term = 14.062 %
Fuel Trim Bank 2 Short Term = 0.781 %
Fuel Trim Bank 2 Long Term = 37.5 %
Engine RPM = 875 rpm
Speed (OBD) = 7.456 mph
Timing Advance = 15 °
Intake Air Temperature = 123.8 °F
Mass Air Flow Rate = 6.62 g/s
Throttle Position(Manifold) = 17.255 %
Run time since engine start = 133 s
O2 Sensor1 Equivalence Ratio = 1.004
O2 Sensor5 Equivalence Ratio = 0.995
Distance travelled since codes cleared = 1.243 miles
Barometric pressure (from vehicle) = 14.504 psi
Catalyst Temperature (Bank 1,Sensor 1) = 839.3 °F
Catalyst Temperature (Bank 2,Sensor 1) = 839.3 °F
Catalyst Temperature (Bank 1,Sensor 2) = 247.64 °F
Catalyst Temperature (Bank 2,Sensor 2) = 247.64 °F
Voltage (Control Module) = 13.164 V
Engine Load(Absolute) = 18.824 %
Commanded Equivalence Ratio(lambda) = 1.005
Relative Throttle Position = 0 %
Absolute Throttle Position B = 49.02 %
Accelerator PedalPosition D = 16.078 %
Accelerator PedalPosition E = 32.157 %

End of report.

81runner · 05-06-2019, 10:07 PM

I would be looking at the o2 sensors and a/f sensor for bank 2. I had bad fuel trims on both banks with a bad fuel pump. It would start out low, and as the pump got hot, the trims would go up. Didn't help I also had fouling injectors on both heads so sometimes it would go waay out of whack. But my exhaust was never rich, which led me to believe the fuel delivery was lacking, which it was. In your case, rich exhaust means delivery works fine, it's the sensor going nuts causing you to dump excess fuel and probably make the engine run a little rough.

earthrealm · 05-08-2019, 03:34 AM

Quote:

Originally Posted by 81runner

I would be looking at the o2 sensors and a/f sensor for bank 2. I had bad fuel trims on both banks with a bad fuel pump. It would start out low, and as the pump got hot, the trims would go up. Didn't help I also had fouling injectors on both heads so sometimes it would go waay out of whack. But my exhaust was never rich, which led me to believe the fuel delivery was lacking, which it was. In your case, rich exhaust means delivery works fine, it's the sensor going nuts causing you to dump excess fuel and probably make the engine run a little rough.

THanks,
any specific way of knowing which sensor is bad?, the AF/upstream sensor is over $100, while the o2/downstrean sensor is about $40, would not want to bblindly throw away cash by swapping out the two,

earthrealm · 06-11-2019, 04:08 PM

Quote:

Originally Posted by 81runner

there are two fuel lines near the brake master cylinder. Black cover is return, white cover is feed. You want feed. Those fuel trims being what they are, my recent experience with this makes me feel like your issues are related to the specific engine bank. If it were fuel pressure, I would think you would get lean codes for both engine Banks. Is your exhaust rich smelling?

so far i have changed the fuel tank cover, changed the drivers side 0xygen sensor, yet the p0174 still refuses to go away, my fuel trims are 36% for bank 2, and 14% for bank 1.

i attempted to do the fuel rail test, disconnected the white&black tab fuel lines, near the brake abs, turned on the ignition, but my guage remained at zero, i disconnected the guage to see if fuel will spray out , but nothing happened, pls what am i doing wrong???

waypoint · 06-11-2019, 06:33 PM

Quote:

Originally Posted by earthrealm

i attempted to do the fuel rail test, disconnected the white&black tab fuel lines, near the brake abs, turned on the ignition, but my guage remained at zero, i disconnected the guage to see if fuel will spray out , but nothing happened, pls what am i doing wrong???

See section 2 of the PDF link I posted...you need to activate the fuel pump. If you don't have a bidirectional scantool to manually switch the pump on, you'll need to plumb the gauge into the fuel line as shown and test w/ the engine running (after ensuring no fuel leaks).

If you have the fuel line dead-headed into the gauge, you may be able to read pressure while cranking or by removing the fuel pump relay and using a jumper wire. Again, ensuring no fuel leaks under pressure.

earthrealm · 06-12-2019, 02:28 AM

thanks for the heads up, am wondering if good ol techstream could be used inplace of the SST.
last option, i am considering simply replacing the fuel pump+filter, and not bother testing the fuel rail, seeems its too much trouble

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