Fuel tank pressure sensors are obsolete??

[bills4065]

2007 Ford ranger evap check: vent valve commanded closed 100%. Vapor management valve closed (off). Fuel tank pressure is negative -0.27 psi. Note fuel tank pressure sensor drops to 1.57 volts. Computer is now watching how quick the negative psi drops and if fails test check engine light will come on.

 

[Curious Hound]

2007 Ford ranger evap check: vent valve commanded closed 100%. Vapor management valve closed (off). Fuel tank pressure is negative -0.27 psi. Note fuel tank pressure sensor drops to 1.57 volts. Computer is now watching how quick the negative psi drops and if fails test check engine light will come on.View attachment 134299

Well, that blows my dummy plug idea sky high.

The junk yards around here poke holes in the tanks. But sensors, pumps, etc. are still useful.

 

[Summers22]

@bills4065
Scanner shows all good! Anything else to check? Tank pressure bounced between 153 and 170, voltage always in the 2.73 to 2.69 up to 2.79. This scanner does a lot more live data than I thought.

 

[bills4065]

Does your scan tool allow you to do a purge and seal test in the special functions section?If it does you could start your truck and then close the vent valve, Then open your purge valve to pull the fuel tank into about a negative .25 psi ,then close your purge valve.You should now have a sealed system from vent valve (rear of truck ) to purge valve (front of truck) If can not get a negative .25 psi or bleeds off very fast there is a leak. A sticking or stuck open purge valve would give you long cranking issues to start after refueling. A stuck open vent valve, the truck would never be able to run the evap monitor test.

 

[Summers22]

Not sure, but I can try that tomorrow. It turns over immediately after refueling. If my scan tool can't perform that, I'll run another smoke test. Is there anything to monitor in the evap portion of a scan otherwise?

 

[bills4065]

As long as your fuel tank pressure sensor voltage is varying with changes in fuel tank pressure, I think your sensor is fine. With Ford more negative pressure your fuel tank sensor voltage will decrease. Should have asked long ago, you did check gas cap for any obvious issues?

 

[Summers22]

Yes, I replaced the gas cap a few months ago with a new Motorcraft cap from rockauto. I plan to do another live stream once the tank level drops or when the check engine light comes on.

 

[Summers22]

My TopDon scanner is not bidirectional, so I can not shut off sensors for testing.