Can't find the evap leak. | Ford Explorer Forums - Serious Explorations

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Can't find the evap leak.


Active Member
January 9, 2009
Reaction score
City, State
Phoenix, AZ
Year, Model & Trim Level
2002 XLT 4WD V8 4.6
Alright, so I have and OBD code for an evap leak AND the check fuel cap light on. I started out by replacing the fuel cap twice and reseting the codes, but they pop back up the next day. Whenever I gas up the car, I get a strong smell of gas inside the cabin.

I can't seem to locate the actual leak though. I doubt having a faulty gas cap would cause the cab to smell like gas ONLY when refueling. Any ideas on how to find it?

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Have you inspected the fuel filler neck? The next time you get gas, fill the tank all the way. Put an extra squirt or two in even after the nozzle clicks to signal that your tank is full. The goal is to get as much gas in the vehicle as you can so that you can check for leaks not only at the bottom of the fuel filler neck, but also at the top where the cap is. Drive around for a couple of minutes, preferably making sharp righthand and lefthand turns, and check the filler neck for wet spots.

I did what you suggested 6Stringer and I couldn't see anything. I ordered another fuel cap, this time Motocraft. We'll see if that does anything. If not, I guess I'll dig around underneath the X around the filler neck and check for holes. I still dont understand why the cabin smells of gas though. I wonder where its coming in from??

I used a locking cap from autozone on my old car . Thing threw a code a few weeks later. Good choice on sticking with the stock one.

But that gas smell would worry me. I would under there and follow all the fuel lines.

GOod luck and keep us updated.

These systems are a PITA to troubleshoot, largely due to being hard to find and see.

Locating the leak with certainty and ease requires use of a low-pressure smoke pressurizing system that the dealership has on hand and costs too much for the do-it-your-selfer. This makes the charge by the dealer a rare good deal, as trying to locate a tiny crack in a rubber vent hose is very hard and can take many frustrating hours.

What they usually find is a cracked rubber evap hose, although occassionally a vacuum valve is discovered to be faulty. For the gas smell, I'm thinking you have a gas vapor leak - like a cracked hose.

Evaporator charcoal canister?

Alright guys, due to my inability to find this leak, I took it to a local shop to smoke the system. I get fleet pricing there so it's only $60. I'll follow up on here with what they find. I'll probably still fix it myself.

Alright we got it fixed now. I didn't mention this before but the codes pulled were:

P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted
P0446 Evaporative Emission Control System Vent Control Circuit Malfunction
and the "Check Gas Cap" light was on

The shop pumped the system with smoke and found one of the hoses to be rotted (what a shocker, eh? ;)) It was the hose to the vapor canister purge valve. They replaced it for free and charged me no labor. Just the $65 to diagnose. Not a bad deal if you ask me. Those leaks are so hard to find on your own. For those of you trying to find the leaks yourselves I wish you all the luck in the world.

Thanks everyone for your input!!!

Edit: Now that I KNOW where this leak is, I feel kinda dumb for not searching around the purge valve better. I mean COME ON look at the codes! They both say to check the stupid purge valve! Dangit!!! Oh well....

ya, but you could have looked at the canister all day long and not seen the hose that was goofed up.

That is a good you got it fixed and didnt charge you extra.

So far so good with no codes popping up. However, ever since changing out that leaking hose the car has occasional hicups while trying to start. What I mean by this is after it sits for a while and I go to start it up, it's doesn't start right away. It acts almost like its not getting fuel. If I give it 1/4 to 1/2 throttle while starting it starts up ok but still acts as though it's not getting enough fuel. Wierd huh. Maybe the computer was compensating for a leaking hose before or something.

Im pretty sure its a fuel filter or fuel pump. If I turn the key to ON and let the fuel pump prime, then turn it off and repeat this 3 times, it's starts right away... The fuel filter is the first to get checked. Its way past due.