Evap system

[buck91]

Been chasing this P0451 code in my 2011 F150 for a long time now.... very slowly. Honestly I haven't been terribly motivated since it doesn't affect any functionality on the truck. I believe I've narrowed it down to a fuel tank pressure sensor. Both purge valve and solenoid function but when the tank is at atmospheric pressure its reading a negative value- confirmed its atmospheric pressure by inserting the fuel funnel into the capless fuel filler. Does this sound right? I guess my next step is to hunt down the fuel tank pressure sensor, which I believe it part of a larger tube complex.

 

[brages]

Are you using aftermarket sensors?

I had a problem with my purge sensor (1997 Ranger) and all the aftermarket ones I tried threw a code. Ended up buying a NOS Motorcraft purge valve+sensor kit and the light went away for good.

 

[buck91]

Are you using aftermarket sensors?

I had a problem with my purge sensor (1997 Ranger) and all the aftermarket ones I tried threw a code. Ended up buying a NOS Motorcraft purge valve+sensor kit and the light went away for good.

No, motorcraft.

 

[Rhymingmechanic]

Check the wiring when you find the sensor. When I got a low pressure sensor code on my Silverado, it turned out that something had chewed the wires to the sensor. A new pigtail fixed it.

 

[clinebarger]

What's the FTP Voltage at atmospheric pressure? 2.35 to 2.9 volts is acceptable. IIRC.....The FTP is part of a vapor line on top of the tank.

 

[jjblbi]

My '14 Ram occasionally throws an evap code especially in the winter. YouTube has some diy smoke machine videos, I made one this winter and will try it once the weather warms. Seems like a good troubleshooting method. Good luck, John