Help, EVAP leak in 06 minivan

[pishta]

was getting minor and major leak codes on scan tool (and obd2 display in odometer- turn ignition on/off 3 times and read on ) so I replaced gas cap, didnt fix so I replaced perceived leaking (by my mightyvac, which turned out to hold vacuum without my mightyvac hose) the vacuum purge control solenoid under car next to charcoal canister (to find every plastic clamp was broken) so I zip tied (per TSB) 3 hose ends then ran out of ties, leaving only the end on the canister unsecured, but its on pretty tight, ie. stuck on. after all that it still tripped a minor leak (P0445) about 60 miles later. any other place to look? interesting that I can reset the code after a fill up and itll hold until 3/4 tank, then trip. dunno if thats just when the monitors kick in or what. no gas smell, and old cap seal looked fine. visible hoses look pliable and in good shape. there is some sort of pressure pump by radiator and I tried to trace hoses back but lost them. I understand the pump pressurizes the EVAP to like 2 psi to test for leaks?

 

[67Dart273]

Sorry buddy I have no documentation at all for stuff in that time

 

[rmchrgr]

The EVAP monitor runs with the tank between 15% and 85% and usually when cold. You need three successful trips for the code to go away. 99.9% of the time a new gas cap won't fix an EVAP leak.

The EVAP system is closed to atmospheric pressure which is how the excess vapors are kept from venting out. The way it works is that the system pressurizes itself and usues a specific leak down timer to gauge if there is a leak. There is a diaphragm in the purge solenoid that acts sort of like a timer but is based on pressure. If the pressure drops too quick, you will get a code depending on the rate of pressure drop. The purge solenoid pushes the excess vapors from the canister into the intake when it reaches a certain level.

You probably have a leak somewhere. Take it somewhere to have it smoke tested. Make sure that whoever smoke tests the car knows to clamp off the vent to fresh air or they won't get a good result.

There's lot's of places for hoses to crack. It's hard to see anything without doing the smoke test, you'd be there for days combing over every line trying to find a tiny crack. It's also best to do this on a lift.

I'd also think about replacing all the hoses that are zip tied. The hoses are prone to cracking, they dry rot and are subject to heat/vibration.

I used to hate EVAP leaks when I was a tech. Time consuming and difficult to get right the first time. Sometimes you knew what it was right away but most of the time you needed to do a smoke test which were often frustratingly inconclusive.