Good evening,

Problem One:
I have a code:P0453 recurring on my 1997 F150 4.6L. I replaced the Canister Vent Solenoid and the Fuel Pressure Sensor when I replaced the tank, while also clearing out the canisters and re-running the line to the EVAP Purge Valve on the firewall (I figured I was already working there and the prior owner was a MacGyver).

The wires to the Purge Valve report 11.62
Resistance on the Purge Valve reports: 31.62
No other Codes

The Purge Valve is the only part I haven't changed. I even replaced the vacuum line from the Purge Valve to the intake manifold. Am I missing something?

 

Why are you screwing with the purge valve? It has nothing to do with that fault code.

P0453 indicates that there is a problem with the FTP sensor, not the valve(s).

 

Not necessarily, the P0453 means the ECM sees that the EVAP Pressure sensor (or FTP) is above 4.5 volts which is indicating a higher than normal pressure in the EVAP system. From there one has to determine why the pressure is so high. Problems with a sticking purge valve is just one of the things that can prevent pressure from bleeding off, resulting in the higher than normal EVAP pressure. It's one of those, "the ankle bone is connected to the leg bone" scenarios.

 

I never tested the wire to the Fuel Tank Pressure Sensor, or the sensor itself. I'll go back under tonight and test those. I gather that resistance north of 4.5 would be bad, but I don't know what voltage I should hope/expect to find in the wire. If you could provide a voltage, that would be helpful.

As to why I'm working at the Valve, that's because it's the only device I've not change out. I cannot think of anything else, that's why I posted. The ohms/volts seem to be within tolerance, though.

 

All the code is telling you is that according to the sensor the EVAP pressure is too high. That could mean the sensor is no good or it could mean the EVAP pressure is too high. Your first step would be to determine if the EVAP pressure is too high, because if it is then the sensor is doing what it's suppose to be doing by reporting a problem.

 

The diagnostic procedure for DTC P0453 in the PCED does not support your interpretation. It indicates that the reading is ABOVE THE MAXIMUM.