PO440

Hello everyone. My 03 has thrown the infamous P0440. I found a broken vacuum line coming from the air hose (vacuum line is called air hose #3). Could this cause a P0440 to come up? Not seeing any obvious leaks in the EVAP system and thought I’d check here first before getting a smoke test done. Any insight would be great. Thanks in advance. Photo linked to hose I’m speaking of.

 

Yeah unfortunately because your vapor canister is all the way in the back there is a lot of real estate to check...

I doubt its that hose coming off that resonator....

I would google 2003 evap system tacoma.......P0440 tacoma.....ect....to find the most common and work backwards....

In the taco world ....you are so lucky.....these people are nut cases.....there are so many images and links...

you just keep stabbing the beast until the right layer comes up...



https://www.tacomaworld.com/threads/2003-tacoma-evap-question.688870/


I will warn you the No1 reason for idle and performance problems is vac leaks...all over the place.....

I would recommend a hose replacement campaign over time .....
and a little smoke machine wont hurt....cause you'll use it in all kinds of places.......like the fuel tank filler neck.

again always start at the simplest and work your way up.......in this case....fuel cap....

the other extreme end....would be the canister itself........dumbest ideal they ever did was put the canister in harms way in the rear chassis area...

 

totally the wrong engine.....but the right ideal......

unless you just dont have the time and money...

 

is all your vacuum deleted?

 

Wow.. I like that a lot. Where did you get those?

 

As you can see the truck has become my hobby.....empty nest....no wife .... syndrome...

Some evap codes you just cant get rid of.....I replaced every dang hose in the fuel and vac/ evap system......just for ocd old man disease....
and then I was rewarded with the 440 code few months later....when there were zero codes before......go figure...

I'd reset.....and got the 440 code over and over...
....
over the year I reset half dozen times...only for it to come back at odd times when the fuel would slip past the 1/4 tank mark .....
And then about a year later.....it just turn itself off.....and hasnt come back for almost a year now....

 

There are..../have been silicone hose kits for 3rz / 5vz over the years that come and go...

mine I just bought by the piece......6mm all the way to 24mm.....high temp turbo geared mods...
and heater hose kits...

and the braided silicone water hoses/ and the pcv fuel vent hose(snow mobile 5/16 clearblue fuel line...10') came off Amazon...

$48 HPS 5/16" ID blue high temp reinforced silicone heater hose 10 feet roll, Max Working Pressure 85 psi, Max Temperature Rating: 350F, Bend Radius: 1-1/4"

Amazon.com: HPS 5/16" ID blue high temp reinforced silicone heater hose 10 feet roll, Max Working Pressure 85 psi, Max Temperature Rating: 350F, Bend Radius: 1-1/4" : Automotive

 

And by the way.....dont ever overfill your gas tank....

for me little over 3/4 tank is full.....and if drops below 1/4.....I get itchy....

Vapor canister on mine is $320........and new a denso fuel pump is $125 and a days work.....



https://www.youtube.com/shorts/72SR5o7zPD0

 

As mentioned above the easiest thing is a gas cap, Toyota only.

What is happening might help you diagnose your problem. This is a generic description of operation. On the fuel tank there is a pressure sensor to sense the vapor pressure/vacuum in the fuel tank. There is a carbon canister to trap these vapors and there are some electric solenoid valves. There is a valve between the top vent hose on the fuel module that leads to the carbon canister that is open by default, this allows the vapor/air in the fuel tank to vent so that you can fill you gas tank. If you continually top off your fuel tank raw gas will get into the carbon in the canister and turn it to mush. There is a vacuum line that comes off the carbon canister that leads up to the engine and there is another solenoid there that is closed 99* of the time. When you start your truck and the fuel tank is above*** 1/4 and below 3/4 full the programming in the powertrain control module (PCM) signals the the purge valve to open and it draws the vapors out of the carbon canister and puts a slight vacuum in the fuel tank system. The purge valve then closes and a timer is started and the pressure in the fuel tank is monitored via the pressure sensor. If after the prescribed time period the vacuum holds, that monitor has run and is completed. If it takes a while for the pressure to drop, you have a small leak, if the pressure drops fast, you have a large vacuum leak. The pressures we are dealing with here are so small thats why a smoke machine is needed. Finding a small leak can be a hair pulling experience.

*** there are other parameters that need to be met in order for the monitors to run such and outside air temp compared to engine coolant temp and time the engine has be sitting, usually 8 hours. This is refereed to as a “drive cycle”. Hope this helps.