noise help - Page 3

Tred · 11-10-2009, 01:03 AM

AC/heater should only make noise when the ignition is at the least in the ACC position. EVAP doesn't have a motor and is vacuum actuated. What makes the noise when the ignition is turned off?

To the OP. Have you actually stuck your head under your truck to see where the noise is coming from?

cantucki · 11-11-2009, 02:01 PM

ye the engine is off and yes i stuck my head to find the noise and that it is underneath by the rear end and bed

**Enola Gaia** · 11-11-2009, 07:13 PM

Is it underneath in the vicinity of the fuel tank?

I have a new theory ... On the 2005+ Tacos with the 2TR 4-cylinder engine, there's an automatic self-test that checks for EVAP leaks after the ignition is turned off. Normally it doesn't kick in until at least 5 hours have elapsed.

The test can start when the engine coolant temperature cools down to 35 degrees C (95 degrees F). If it hasn't cooled down enough after 5 hours it'll try again in 2 hours.

This test involves a 'leak detection pump' that cranks up to create negative pressure. If this pressure doesn't hold (indicating a leak in the EVAP system somewhere), the ECM is supposed to throw a code.

This 'leak detection pump' is embedded within the Canister Pump Module (which according to the FSM isn't to be disassembled).

I'm wondering if what you're hearing is this leak detection pump doing the self-test. If it's happening on and on, maybe the pump is stuck or the control system is leaving it on too long.

Here (attached) is a diagram from the 2005 FSM illustrating the location of the Canister Pump Module. It's apparently found inboard of the fuel tank, and maybe above it.

Tred · 11-11-2009, 08:04 PM

Wow. Interesting.

TACOMATruckin98 · 11-11-2009, 10:19 PM

yeah, if it stays on, then you may have a problem, but it shouldnt run for too long, and that pump is the one where if you leave the fuel cap off/loose you'll jump in and the MIL will suddenly be on

cantucki · 11-14-2009, 03:11 PM

thanks people it helped alot... so is it supposed to do that all the everytime after i drive

TACOMATruckin98 · 11-14-2009, 06:45 PM

yes it just means its working normally, all its doing is making sure that there are no leaks for the gas fumes to escape and pollute, all about emissions

cantucki · 11-14-2009, 08:33 PM

shoots thanks people toyota for life