Fuel tank pressure vs. evap purge

[mikez71]

Just had a thought, the initial vent closure that happens shortly after startup, maybe the gas cap test. The system is sealed for 1 min 36 seconds. In that time my tank pressure started at 1.51V, peaked at 1.60V, ended at 1.54V. Could be testing that pressure builds as the pump heats up? If cap leaks, maybe pressure won't increase.. Since it's early and there is never any purge action, that maybe when it tests for leaks/gas cap message.

 

[mountie]

Just had a thought, the initial vent closure that happens shortly after startup, maybe the gas cap test. The system is sealed for 1 min 36 seconds. In that time my tank pressure started at 1.51V, peaked at 1.60V, ended at 1.54V. Could be testing that pressure builds as the pump heats up? If cap leaks, maybe pressure won't increase.. Since it's early and there is never any purge action, that maybe when it tests for leaks/gas cap message.

a couple years ago i replaced the gas cap….. I had the “ tighten cap” message….
I then bought an OEM / at dealer cap……. Still the message….. I wanted to make sure…..
But still ,that intake solenoid replacement I think helped….. I think...

 

[mikez71]

The procedure on charm.li tells you to tap your purge solenoid to see if any carbon falls out.
Could be they get gunked up and not seal.
Not sealing to the intake would not let pressure build forsure.
(not sealing anywhere for that matter)

Did the gas cap message show up within 2 minutes of startup?

 

[mountie]

The procedure on charm.li tells you to tap your purge solenoid to see if any carbon falls out.
Could be they get gunked up and not seal.
Not sealing to the intake would not let pressure build forsure.
(not sealing anywhere for that matter)

Did the gas cap message show up within 2 minutes of startup?

Yea, the old purge solenoid had junk in it…. The new one made a difference….. about 85% better…. made the problem manageable.

 

[mikez71]

In your case, the purge must not have sealed when closed..
Vent valve maybe worth checking.. (Just because it's easy to replace and fairly cheap)
You would have to apply voltage to close it.. And then hook up your mityvac or airpump..

But it could be anywhere.. EVAP lines, filler hose, fuel pump gasket, canister.. Maybe a smoke test is the way to go..
Smoke was used in a south main video, sequel to the one @Fless linked in post #5.
In that video the fuel filler tube had a rusty pinhole..