Evap system clogged?

[white90dx]

Hey guys...

I've been trying to figure out what's up with the Evap system on my Camry for a while now (obviously not trying very hard though! ) and haven't found what's wrong. It seems that my gas tank gets pressurized after running for a while. Instead of sucking in fumes when I open the gas tank, it blows out (say, at the gas station or whatever). It also seems to have made the leak at the gas tank filler seal at the tank leak worse (right now, I just put in 5 gallons at a time to keep the level below that seal until I can replace it).

I hooked up up the evap system correctly (I think!) when I did the swap. The vacuum line to the motor sees manifold pressure all the time (checked with my boost gauge), and has a one way valve that only allows air to flow from the evap canister to the motor so no boost pressure goes to the tank. I think the pressure build up in the tank is from the fuel warming up while driving (fuel heating as it is pumped up to 40-60psi flowing by the engine then back to the tank).

Where else should I check for problems? I seem to remember my only Camry doing about the same, but I think it would suck air into the tank when the gas cap was opened? I still want to keep my evap system working (gas fumes around my car that blows fireballs = not a good thing!).

Anybody have any ideas? (I'm lookin' at you, Dr. J!)

-Charlie

[toyomoho]

The tank can pressurize depending on how much the gas vaporizes. The EVAP system is supposed to cycle to purge the tank of fumes and store them in the canister if they cannot be burned in the engine. The system is controlled by VSV’s. plus there may be a pressure sensor.

Might check all the vacuum lines to make sure they are not plugged, the VSV’s work, the wiring to all the valves and pressure sensor is installed OK.

The tank should have a relief valve to prevent over pressurization. For the system to work property the tank needs to be sealed with no leaks.

See of there are any trouble codes stored on the computer.

[white90dx]

Originally Posted by toyomoho

The tank can pressurize depending on how much the gas vaporizes. The EVAP system is supposed to cycle to purge the tank of fumes and store them in the canister if they cannot be burned in the engine. The system is controlled by VSV’s. plus there may be a pressure sensor.

Might check all the vacuum lines to make sure they are not plugged, the VSV’s work, the wiring to all the valves and pressure sensor is installed OK.

The tank should have a relief valve to prevent over pressurization. For the system to work property the tank needs to be sealed with no leaks.

See of there are any trouble codes stored on the computer.

Yeah, I figured the pressure in the tank was from vaporization (and heat). No surprise there.

The gen2 Camry stock Evap system has no VSVs or pressure sensors. Nothing in the wiring diagrams, no hardware that I found. The Evap canister in the engine bay has two ports on the top and one on the bottom. On the top, one goes to the engine and one goes to the tank. The one on the bottom is open to atmosphere (unless something is missing from my car!). The Celica GT4 that my motor came from had one VSV in the system, but no pressure sensors in the evap system. I got rid of that because it wouldn't easily mount on the Camry evap canister. There are no codes stored because of this (no check engine lights).

-Charlie

[toyomoho]

The Gen_2 system shows a BVSV valve that is controlled by coolant temp. This valve would then control tank venting to canister and engine.

The link below provides more detail.

http://www.camrymanuals.com/manuals/...on_Control.pdf

[white90dx]

Originally Posted by toyomoho

The Gen_2 system shows a BVSV valve that is controlled by coolant temp. This valve would then control tank venting to canister and engine.

The link below provides more detail.

http://www.camrymanuals.com/manuals/...on_Control.pdf

LOL... yeah, that's LONG gone, even on my original motor (the ports broke off, so I just bypassed it). That's only there to keep the evap system closed until the motor is warm. That doesn't exist on the 3s-gte in my car.

-Charlie