EVAP System Troubleshooting

[Rick99]

I am getting a code P0456 from the PCM (small leak in the evaporative emissions system) on my wife's 2001 T&C and need to find the leak. I have already replace the gas cap with a new one from the dealer, so I can rule that out. All the hoses and cannisters look like they're in great shape on a visual inspection.

What I'm wondering is if anyone has devised a way to find a leak in the system without owning the special diagnostic tools.

I've been thinking about using compressed air to slightly pressurize the system, then use a soap solution on the lines to find the leak, but I'm not sure how I would connect the air without hurting anything (and how much pressure I could use).

Has anyone done this? Any other good ideas?

[Rick99]

Ttt

[davet]

Check the hoses running to the evap canister purge solenoid. The rubber hoses running from the tank up to the engine compartment and into the purge solenoid then into the inatke manifold. They look good on the tops of the hoses but the undersides are where the cracks usually appear and they are hairline cracks. I would guess that the hoses are cracked where they go into the solenoid or where they go into the intake manifold from the purge solenoid. My buddy had same code on his Dakota and 2 minutes worth of looking at the hoses found the problem. We cut 1/2" off the end and reconnected it. No problems.

[Rick99]

Thanks! I check that.

[sd5187]

I also had the EVAP code on my 2001. Had to replace 2 of the hoses to resolve the issue.

[gas28man]

The best way to check for an EVAP leak is with a spray can of fuel injector cleaner. I use STP's, but there are others. Have the vehicle running, and then, where you suspect a leak (like at any junction or connection or gasket), spray a little bit of the cleaner. If the engine RPMs go up, you have found the leak.

This is an old racer's trick to find leaky carb gaskets and vacuum lines.

Good luck.

Rick