Fuel Tank Pressure Sensor Voltage
I have a question for the NIssan Guru's out there. I have this Maxima and have verified all of the solenoids will function manually for evap control. Unfortunately the vehicle has a full tank of fuel at this time and unable to do a road test to meet the criteria for the Evap monitor test drive.
My question is what is the maximum variance allowed for the the Fuel Tank Pressure sensor voltage. All the specs I read are 3.34 Volts to 3.4 Volts with the system at atmospheric pressure. This vehicle sensor is at 3.06 Volts. I know for a fact that this variance would cause a fault on a Honda and Toyota but unable to find what the allowable variance is for a Nissan.
First question, are you experiencing any issues with vehicle? What year Nissan? Next question, under what condition do you see this voltage KOEO or KOER? Last question, if you remove the hose from the sensor what is the reading?
This will not set a code for tank pressure off by this amount.
Keep in mind that this system also includes a fuel tank temperature sensor that must rise a minimum of 4 degree F before the monitor can run. Also, this system tests under pressure, not vacuum, when the vehicle is in decel condition. If you need the actual drive cycle for this vehicle that works let me know.
You could close the vent sol, then energize the purge sol to create a vacuum in the tank to see what the pressure sensor voltage is under a vacuum. Then apply some pressure in the tank thru a smoke machine to see how high the pressure sensor voltage climbs to. If you scope the sensor over time, you could ck the signal for any glitches or drop outs.
After many road tests verifying the system functioned as normal I installed a new FTP sensor. The new sensor voltage was 3.40 volts after installation with KOEO. I reset the light and have had the customer return after 2 weeks of driving, Evap monitor ran and passed. So the specification is apparently not + or - a percentage. Some reference material in the trouble shooting specs stated the minimum was 3.00 volts. That is an inaccurate number in my case. I hope this information helps someone.
After I knew vehicle was repaired I took the sensor apart and believe the issue was a poor solder connection inside the sensor. When tugging on the wires 2 held and the 3rd wire broke with very little effort. I don't recall which one though. This was in December and have lost all the pictures on my PC due to a hard drive failure.