My 2004 Prius sat for 4 weeks while I rebuilt the battery. After about 2 days of driving the vehicle the check engine light came on. The diagnostic code pulled was a P0446. This is an evap code. While driving the car the scan tool showed the valve opening to 100%. This is with a full tank. Once the vacuum reached -0.5 PSI it would immediately close the valve. The pressure immediately dropped also. When I did fill the tank, the pump repeatedly would shut off. This sounds like a vent solenoid stuck partly open. No other fault codes have been generated so far.
Have you seen this? Does Wisconsin salt its roads? In areas that do that having actual holes somewhere in the evap system is a possibility.
Yes. I have seen this video. I will be doing a smoke test. This should verify any leaks and proper vent valve function. Before ordering a $90 part i want to verify it's bad. My vent valve is very rusty. After 20 years in a salt bath.
Did the smoke test. The only place smoke came out was by the gas cap, and inside the fender at the top of gas filler neck. I did not see a lot of smoke. It came out some small holes. This looks like the vent for EVAP system. The gas cap will be replaced later today. When the engine is running. The purge valve ramps up to 100%. Fuel tank pressure shows -0.5 PSI. I suspect that the vent valve is stuck partly closed or charcoal canister is having a problem. $300 Cost. The vent valve is very rusty. The gas cap replacement will not solve the gas pump shutting off repeatedly during a fill.
Did you pull the electrical connector off the vent valve? With that much rust it wouldn't be surprising if the inside connectors were corroded too. Although, given all that rust, the valve might break apart from the force of trying to pull the connector off.
If the connector comes off why not test the valve? I know you said that the smoke test would show that the valve works, but if it wasn't exercised electrically, wouldn't that just show that it is in one state and not that that it can switch states correctly? Also the clamp on the middle hose looks rusty enough to fail if the tabs are squeezed.
Does your scantool have bidirectional controls? It's easy to test that solenoid valve if you can tell the ECM to turn it on and off. A common fault is that the valve is mechanically stuck (should "click" when cycled). It is possible to fit jumper wires up there but the access is poor. You can take it out to check it, but at that point I'd replace it anyway (not sure it would survive the process). FYI, that part is the "switching" solenoid valve, not the vent valve. It's still possible for it to be your problem. Posted via the PriusChat mobile app.
Yes, i do have have a bidirectional scan tool (Xtool D8). Over the weekend I ran some test manual test. The purge valve did open when power was applied. On the other hand the vent valve would not change state. It was stuck in the closed state. This would cause the gas pump to shut off during a fill, also fault 0446. I have the vent valve on order from rock auto. At least I don't have to replace the charcoal canister. When the valve is not powered. You should be able to blow air from the center port to the one by the electrical connector. Also: I had to drive 230 miles before the check engine light came on. I had to below a half tank for EVAP test to even run. I couldn't at first figure out why the check engine light would not come on. A issue was when driving i was pulling 0.5 psi vacuum. This should of been a lot lower. Also the purge valve was opening 100%. The purge valve should modulate at much lower value when driving.
Just be aware, there are 3 solenoid valves on the 2004-2005 system. Toyota (and scantool engineers) are wonderfully inconsistent in nomenclature. 1 is the actual "purge" valve - located on the engine intake manifold. This is the valve that will vary the percentage of opening. 2 is the "switching" valve that's next to the canister on the center rear of the fuel tank. (that's the one in your picture and on the scandata) It is either on (100%) or off (0%). 3 is the vent valve (might be called "canister close valve") and is located on top right of fuel tank next to the secondary (trap) canister. Again this is an on or off solenoid, and "seals" the evap system during leak testing. When open it's the sole vent for the fuel system (to the filter on the filler pipe). Posted via the PriusChat mobile app.
1) The purge valve is located right by the intake manifold by the air box. This is the one that can very it's opening. 2) The vent valve on the back center of the fuel tank has 3 hoses attached to it. The center hose switches from the left hose to the right hose when powered. Mine was always stuck on the right port. 3) I did not know about the third valve. Is this valve electronically actuated?
