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Discussion Starter #1
So I have had this issue for a while now. I back probed the ECU FPS signal wire running from the ECU to the fuel tank pressure sensor at the ECU and it isn't putting out a signal at all. Whether it just sitting there on the accessory on position or while the car is running my multi-meter doesn't pickup any current(should be between 0-5v right?). I also checked the grounding point at the left rear pillar and it is good but just to make sure I even sanded the point down to make sure its getting good contact. I probed the yellow green wire (FPS Signal wire) while grounding it. My question is how exactly does the circuit work I thought it should always be putting out some sort of signal even if the car isnt started. Is there any way to fix this issue or am I just screwed?

-John
 

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So my multi-meter doesn't pickup any current(should be between 0-5v right?).

My question is how exactly does the circuit work I thought it should always be putting out some sort of signal even if the car isnt started. Is there any way to fix this issue or am I just screwed?

-John
John, your issue is that you do not have an understanding of electricity...

Voltage is not current (amps).

The 5vdc is a reference, and is changed as the ECU activates the vent solenoid..

That current would be in Mamps...

Your circuit would be system power (12vdc), not the reference, test loaded with a 4amp load...

... Philip
 

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Discussion Starter #3
As far as I have read the FPS is used in part for emissions and should be checking the fuel tank on a regular basis to see if the pressure inside the tank has changed at all to make sure there is nothing leaking into the atmosphere. Taking this into account it should always have some sort of voltage going to it yes? Well I have tried while the car is off, while the keys are in the ignition on the accessory on position and also while the car is running and the sensor is not receiving a single volt.
 

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confirm that the sensor has 3 wires, power(reference), grnd and signal.

Circuit should be active KOEO, and KOER.. FUEL 1/4 TO 3/4.

Do you have the ref on any other circuit eg: TPS?

... Philip
 

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Discussion Starter #5
OK sorry I just retested the sensor is getting voltage. The ref wire is getting a constant 5.06v and the signal is getting a constant 0.10v
 

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OBD-II Code P0451 is defined as a Evaporative Control System Pressure Sensor Range/Performance. The Code P0451 indicates that the Evaporative Pressure Sensor is indicating pressure change values that are not within specification, during the EVAP Monitor test and/or the operation of the vehicle.

What type of live data scanner might you have?
Your sensor is working, but may not be performing to spec... or the tank vent may be at fault (plugged filter/exhaust).
Have you smoked the system?

.... Philip
 

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Discussion Starter #10 (Edited)
no no I am getting the code P0452 not P0451. The P0452 states "Evaporative system pressure sensor circuit low". I think I might try and vacuum test the purge valve but I have to buy a vacuum pump.
 

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no no I am getting the code P0452 not P0451. The P0452 states "Evaporative system pressure sensor circuit low".
that code can also be caused by a split line between the tank and the evap canister

Dont instantly condemn the sensor before checking ALL the evap components.

The PCM has determined that the system pressure is unusually low indicating a problem in the system, not necessarily just at the sensor.
 

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Discussion Starter #12
that code can also be caused by a split line between the tank and the evap canister

Dont instantly condemn the sensor before checking ALL the evap components.

The PCM has determined that the system pressure is unusually low indicating a problem in the system, not necessarily just at the sensor.
I know its not the sensor because I just replaced the whole fuel pump. I even went as far as going to the junkyard to try and use another sensor and still the code keeps popping up. I am afraid I will just have to go through each component individually I guess.
 

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I know its not the sensor because I just replaced the whole fuel pump. I even went as far as going to the junkyard to try and use another sensor and still the code keeps popping up. I am afraid I will just have to go through each component individually I guess.
smoke test the system, and check the purge valve as well.
 
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