P0455 large evap leak - suggestions?

[decolores9]

2000 Ranger 2WD 2.4L, started throwing a P0455 code. I have replaced the gas cap with an OEM replacement, the filler and vent hoses from the filler neck to the tank, cleaned up the filler neck (does not seem to be perforated), and the solenoid and the hose from the cannister to the solenoid. Thought the solenoid fixed it, but the light came back on this morning.

Any suggestions on common failure modes, things to check, how to diagnose the cause? I'm thinking of disconnecting the vent hose at the filler neck and using a hand pump to pressurize the system to see if it holds. Unfortunately I don't have a smoke machine.

Thanks.

 

[tomw]

Can you put a small or slight pressure or vacuum on the canister itself? It may have cracked or broken and become unable to seal successfully. A backfire can send a pressure pulse that might crack old plastic that has become brittle.
There is a solenoid operated valve, I thought to regulate flow from the canister to the intake manifold. If that valve leaks, it would not allow pressure in the system.
Are there two valves in your system?
tom

 

[decolores9]

Can you put a small or slight pressure or vacuum on the canister itself? It may have cracked or broken and become unable to seal successfully. A backfire can send a pressure pulse that might crack old plastic that has become brittle.
There is a solenoid operated valve, I thought to regulate flow from the canister to the intake manifold. If that valve leaks, it would not allow pressure in the system.
Are there two valves in your system?
tom

I can test the canister, now that I had it out to replace the solenoid it should come out fairly easily. Did not see any visible damage, but I also did not take the canister out of it's enclosure.

There are two valves, the Vapor Canister Purge Valve and the Vapor Canister Vent Solenoid. The vent solenoid is the one I replaced, because it looked damaged and several sources suggest it is the more common failure point.

Thanks.

 

[tomw]

I think I would try disconnecting the tube from the tank to the valve and checking that it is intact from under the hood back to the tank. If that checks, then the 'leak' is underhood somewhere. Canister or valves or line to the intake(? maybe not).
tom

 

[decolores9]

Thanks for the suggestions.

I pulled the bed off (again!) and rechecked the (new) filler tube hose and vent hose. I also sealed them with silicone gasket material in case they weren't sealing well.

I used a Halloween smoke generator into the filler neck to "smoke" it, but still could not see any leaks.

I do smell a slight gas smell around the area of the filler cap. I did replace the filler cap, but is it possible it is not sealing against the (original) filler tube correctly? How could I test for that?

It could also be the hose from the engine back to the valve, that hose also runs inside the frame rail underneath the filler tube. I have visually inspected that line and did not see anything, but there are several places where it is very hard to see, such between the tank and the frame rail.

I'm mostly trying to figure out a way to find the actual problem so I am not just "shotgunning" it and replacing parts.

Thanks.

 

[adsm08]

Also make sure the solenoid at the intake is working. 455 is a large leak/no flow code. Because of the way the system works it has problems telling the difference between the system being open, and the system being sealed and not flowing when it's supposed to.

 

[decolores9]

Also make sure the solenoid at the intake is working. 455 is a large leak/no flow code. Because of the way the system works it has problems telling the difference between the system being open, and the system being sealed and not flowing when it's supposed to.

I previously replaced the solenoid that is by the canister, and the associated hoses. Do you mean a different solenoid? There is another module in the engine compartment, is that what you mean? Is there a way to test this without a special scan tool?

Thanks.

 

[enjr44]

I previously replaced the solenoid that is by the canister, and the associated hoses. Do you mean a different solenoid? There is another module in the engine compartment, is that what you mean? Is there a way to test this without a special scan tool?

Thanks.

Yep, I think may be called a vapor management valve. It opens to allow the vapor to drawn into the engine.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=2000+ranger+vapor+management+valve