2003 Tacoma evap question

Hello,
I'm new to the forum and would like to ask a question.
My 2003 Tacoma has an evap problem i can't get rid of. The check engine light is perpetual. I replaced the canister purge valve in the engine bay and the one on the canister. I replaced vaccum lines that looked bad. Now it's starting that every time I get gas it won't idle for a few miles, then straightens out.
I have no idea what the problem could be.
3.4l, Also a new gas cap. I don't know.
Thanks for suggestions in advance.

 

Did you try replacing the entire canister? Mine has this problem every 5-6 years or so.

 

What code(s) are you getting?

 

Fuel vapor pressure sensor or seal on fuel pump access panel ?
Both are on top of gas tank.
Ever do a smoke test?

 

Thanks all the replies. It goes this Friday for a smoke test. No i didn't replace the entire canister. Was considering that. The frame was replaced on it about a year ago, and was wondering if they pinched a wire or something but didn't see anything. The code is po446. It just seems strange that the idle is only rough when I get gas, or remove the gas cap. I never heard of that before.
Thanks for the replies. I think I'll replace the charcoal canister. A dirty IAC valve.

 

P0446 is for the vent valve at the canister

When the pcm commands it to open or close it expects to see a change in vapor pressure read through the fuel tank pressure sensor. If it does not see a change in pressure it sets the code.

As far as the pcm is concerned, on a properly functioning system (with the gas cap tight), the only path to fresh air is through the vent valve.

Electrically, it could have a broken or pinched wire (between vent valve and pcm)

Mechanically, the valve could have an obstruction preventing it from opening or closing.

Or for example, if the canister itself is cracked and leaking or there is a leak in a hose, the pcm might think the vent valve is stuck open.

Using smoke, look for any leaks. Manually close off the vent path by blocking it and look for leaks. If you can command the vent valve to close by jumping power to it, even better.. if smoke is coming out of the vent valve and its commanded closed, its bad.

 

Thank you very much. Are you a mechanic? Sure sound like one. I will do that. I was stomped by this. A garage replaced the one on the canister, and i replaced the one in the engine bay. It ran for two weeks before the light came on again. I had it inspected right after i put in on and it passed emissions. I live in Pennsylvania and i explained to the mechanic all the monitors might not be set yet. He said three of the four were set and that's enough to pass Pennsylvania emissions. So whatever monitor set last, i think I'll replace the canister and go from there. It has 145,000 miles on it and runs great. 3.4L are bulletproof. I love my truck and want to get it right. Thank you for replying. I also have a 2012 Tacoma sport and would rather drive the 2003.
2012 is a gas hog.

 

Thats why you likely have a leak somewhere like a cracked canister or hose..

Don't rule out a pinched wire, you mentioned the frame was replaced. Absolutely they could have nicked a wire or something.

Remember, as far as the pcm can tell..
- A leak in the system looks like an unresponsive vent valve (this includes a gas cap that doesn't seal)
- A broken/frayed wire going to the vent valve looks like an unresponsive vent valve
- A blocked vent path to fresh air looks like an unresponsive vent valve
- A fuel tank (vapor) pressure sensor that is stuck on the same voltage and never fluctuates, looks like an unresponsive vent valve

 

thats what mine was. my gas tank fell off and after getting it back on i got that code.
the check engine light for that doesnt come on for at least over 1000 miles though.at least in my case.

 

Gas tank fell off??

 

almost. the bracket that holds it up rusted off and the back end of the tank was hanging.

 

Were you having any issues before messing with the gas tank area? I've had the three evap codes for a while and the truck runs fine. Only thing I've dealt with is the mild smell of gasoline when I'm outside near the fuel door.

 

what has happened in the trucks past life is that the previous owner(s) just kept squeezing gas into the tank after the pump clicked the nozzle off. All this does is saturate the charcoal in the canister with raw gas and it turns to mush. With the purge valve open and/or the gas cap off, the engine is pulling in additional gas/vapor, enough to cause it to run rough.

 

I chased the same thing for a while on my '03 with 250K miles. Turned out to be the fuel pump cover plate seal where it bolts to the gas tank. After 17 years of running the ethanol crap gasoline my gasket was hard as rock. Replaced the gasket, and fuel pump while I was in there and codes gone.
just a place to check.