Tacoma EVAP Leak Detection Pump

I have 2016 Toyota Tacoma with EVAP code, small leak P0456 and P0453. I did easy stuff first and replaced purge valve at engine and new gas cap. Still error code so I decided I was up for the challenge. I connected smoke machine at purge valve. I discovered the leak detection pump and vent valve are together. If I use bidirectional scanner and close vent, small amount of smoke still exits from vent hose. Pressure gage on smoke machine never drops to zero indicating small leak. I purchased new LDP and same issue. I return and bought EVAP canister with LDP and same issue. If I place my thumb over vent valve tube, smoke machine gage drops to zero indicating no leaks. Are the LDP and vent in same unit? Should I do more than simply close the vent to find leaks? BTW, I sprayed soapy water anywhere a tube connected to my gas tank; no bubbles so no leak. Could this be electrical problem where the 3 vent valves/LDP are not closing all the way?

 

The vent valve on a Toyota LDP evap system does not seal the system when it is commanded closed, you have to cap the vent line to seal the system for a manual leak search.

I made that mistake and misdiagnosed one before I knew that.

Being you have a code for the pressure sensor circuit (P0453) I'd diagnose that before worrying about a leak code.

What does the pressure sensor read with the gas cap off?

 

Welcome to TW..

 

Welcome aboard!

 

Thank you DM for clarifying LDP. When I cap off the LDP, smoke machine reads zero on pressure sensor which I assume means no leaks. When I take the gas cap off, the smoke machine pressure gauge jumps up to the top which is 5.
I’ve watch so many videos thinking when the vent is closed I should see zero unless there are leaks and I would see smoke where the leak is.
Where is the pressure sensor on the tank? I see 3 caps on gas tank.

• I see the gas inlet.
• I see the vent tube going from gas tank to canister.
• I see a 3rd small cap that has a small tube that leads up the gas fill pipe.

Am I correct the 3rd cap has the pressure sensor under it? Is it easy to change?

 

The pressure sensor is integrated into the Leak Detection Pump which is on the Charcoal Canister, I would want to look at scan data and see what the sensor is reading.

 

Since I had a Leak Detection Pump on hand, I decided to replace the LDP on the evap canister with a new one and see what happens. I cleared the codes and have to wait for computer to recheck sensors. I’ve put about 50 mi on. Will wait another 50 mi and see if dash warning lights reappear.

 

Turns out replacing the LDP fixed the problem. I’ve driven my truck for about 200 mi and the check engine light has not returned. I appreciate all the help especially Dm93 for telling me where to find the pressure sensor which is integrated into the Leak Detection Pump.
Thanks again!