Too much vacuum in fuel tank?
Jul 19, 2013 | 10:43 PM
#1
Too much vacuum in fuel tank?
So I have a P0453 code, but I used HPTuners to confirm that the fuel pressure sensor is working properly. It is building up pressure and the sensor shows about 4.5 volts. Unscrew the cap and it drops to 1. The tank is even showing signs of deforming from the suction but I just noticed because I have been too lazy to scan the code for a while. Is this the usual dirt obstruction problem that a new evap pump and rerouting the hoses will fix?
Jul 21, 2013 | 12:20 AM
#4
I swapped gas caps and it still had the problem. I inspected the evap vacuum thing and the two openings in it were packed with dirt all the way to the top. Would this cause the excessive suction inside the tank? I tried to get the dirt out, but I couldn't get it all and it is still happening.
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Jul 21, 2013 | 09:51 PM
#8
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That's not quite correct. The PCM is supposed to modulate the pressure state of the tank via the purge valves. The fuel cap is supposed to relieve positive pressure should it build up, negative pressure is controlled by the PCM and vacuum system. P0453 indicates gross overpressure or faulty electronics.
CashDudeHomie, your problem may be a defective sensor or damaged wiring. The actual diagnostic goes from checking the harness, replacing the sensor and then replacing the PCM as a last resort.
Originally Posted by Service Manual
CIRCUIT DESCRIPTION
The control module monitors the fuel tank pressure (FTP) sensor signal in order to detect vacuum decay and excess vacuum during the enhanced evaporative emission (EVAP) diagnostic. The control module supplies a 5-volt reference and ground to the sensor. The FTP sensor signal voltage increases when the FTP decreases. Negative pressure or vacuum indicates high voltage. The FTP sensor signal voltage decreases when the FTP increases. Positive pressure indicates low voltage. This DTC sets when the FTP sensor signal goes below a predetermined value.
CONDITIONS FOR RUNNING THE DTC
The engine is running
CONDITIONS FOR SETTING THE DTC
The control module monitors the fuel tank pressure (FTP) sensor signal in order to detect vacuum decay and excess vacuum during the enhanced evaporative emission (EVAP) diagnostic. The control module supplies a 5-volt reference and ground to the sensor. The FTP sensor signal voltage increases when the FTP decreases. Negative pressure or vacuum indicates high voltage. The FTP sensor signal voltage decreases when the FTP increases. Positive pressure indicates low voltage. This DTC sets when the FTP sensor signal goes below a predetermined value.
CONDITIONS FOR RUNNING THE DTC
The engine is running
CONDITIONS FOR SETTING THE DTC
- The FTP sensor voltage is less than 0.1 volts
- All conditions are present for more than 5 seconds
Last edited by Suburbazine; Jul 21, 2013 at 09:57 PM.
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