Evap Question

[tekfire07]

Hello I have fuel leaking from the line on the left. What is causing this and what needs to be replaced?
Thanks in advance for any help.
!
Erik

 

[rdezs]

Year, make, mileage, and any trouble codes? If you don't have a code reader yet, most auto parts stores will plug in and read the codes for you.

That appears to be the back side of your fuel filler assembly, and looks damp at the top of the fuel vapor vent.

If you don't have any codes, and no check engine light, my first thought is your topping off your fuel tank. That's definitely something you do not want to do in these vehicles. As soon as the pump clicks, pull the nozzle out. Bad things happen from continuing to top it off.... Like flooding the carbon canister that absorbs vapors, breaking loose the carbon pellets inside and then they work their way through out your fuel system.

The side effects of "topping it off" can be worse depending on your location. In Tucson Arizona in August, if you park it with a full tank for a day.... The heat will expand the fuel in the tank and it has to go somewhere. Not so much a problem in Prudhoe Bay Alaska.

If you are not topping it off, you'll need to plug in with a scanner and monitor the EVAP system to make sure the components are functioning correctly. (Like the evap solenoid mounted on the intake manifold. It opens and closes, controlled by the ECM, to burn off fuel vapor. If it's stuck closed, that becomes as much of an issue as becoming stuck open, which ends up flooding the engine and giving you difficult starting)

Most places these days want around 180 to $200 to plug in, and diagnose an issue. For that price you can get a bidirectional scanner that will tell you what you need to know. Considering that one use pretty much pays for itself, it actually is well worth spending a couple hundred more for a better quality unit.

But I always recommend starting with the least expensive option. Make sure the tank isn't being overfilled.... And then take a look at it again. There's a good chance that will solve your problem.

 

[tekfire07]

Year, make, mileage, and any trouble codes? If you don't have a code reader yet, most auto parts stores will plug in and read the codes for you.

That appears to be the back side of your fuel filler assembly, and looks damp at the top of the fuel vapor vent.

If you don't have any codes, and no check engine light, my first thought is your topping off your fuel tank. That's definitely something you do not want to do in these vehicles. As soon as the pump clicks, pull the nozzle out. Bad things happen from continuing to top it off.... Like flooding the carbon canister that absorbs vapors, breaking loose the carbon pellets inside and then they work their way through out your fuel system.

The side effects of "topping it off" can be worse depending on your location. In Tucson Arizona in August, if you park it with a full tank for a day.... The heat will expand the fuel in the tank and it has to go somewhere. Not so much a problem in Prudhoe Bay Alaska.

If you are not topping it off, you'll need to plug in with a scanner and monitor the EVAP system to make sure the components are functioning correctly. (Like the evap solenoid mounted on the intake manifold. It opens and closes, controlled by the ECM, to burn off fuel vapor. If it's stuck closed, that becomes as much of an issue as becoming stuck open, which ends up flooding the engine and giving you difficult starting)

Most places these days want around 180 to $200 to plug in, and diagnose an issue. For that price you can get a bidirectional scanner that will tell you what you need to know. Considering that one use pretty much pays for itself, it actually is well worth spending a couple hundred more for a better quality unit.

But I always recommend starting with the least expensive option. Make sure the tank isn't being overfilled.... And then take a look at it again. There's a good chance that will solve your problem.

2009 Tahor flex fuel
195360 miles

I did get a P305 code misfire #5 cylinder.

I checked it out. I found nothing wrong cleared the code. It has not come back.

I do have a permanent p420 code for the cat.

I have not over filled the tank. This appeared after filling the tank to 3/4 of a tank. Took a road trip yesterday. Made a stop, smelt fuel, no signs of leaking. Got to my destination and a puddle was forming under the truck near the fuel filler. I am at a loss with codes.

 

[rdezs]

I would think if the evap solenoid on the intake manifold was stuck closed, pressure would build in a fuel tank.... But I would expect to see a check engine light, and from even three quarters of a tank that would be a lot of fuel to expand to push up that far.

That hose leads up to basically just a vent at the end of the hose. At the lower end of the hose is the vent solenoid. Works in conjunction with the purge solenoid on the intake manifold. The one on the intake manifold opens up at rpm, controlled by the ECM.... Burns off fuel vapors.... vent solenoid opens to let fresh air in. Fuel tank pressures also monitored by the ECM.


It would be a good idea to get a scanner, bidirectional, so you can monitor what's going on with the EVAP system and the fuel tank while driving.

A common issue is the charcoal canister itself, at the rear of the fuel tank you'll see it mounted on a bracket. Couple times being overfilled and the pellets break loose, cause all sorts of problems. I would want to see what it's doing now before purchasing a new charcoal canister, vent solenoid and purge solenoid. (To avoid shooting the parts cannon at it. However, at your mileage replacement of those items should be on a standard maintenance list.)

 

[rdezs]

.... Just like the plastic heater hose fittings at the firewall.

 

[tekfire07]

I have replaced those all ready. What kind of maintenance intervals should the evap components be replaced at? What should I be looking for with the live data?

 

[rdezs]

Maintenance interval for evap system....most wait until there's an issue, but the parts aren't expensive....I did my wife's Escalade around 170,000 while I was replacing her fuel pump. Depends how proactive you want to be, but 200,000 is longer than expected life I would say.

Watch on a scanner, live data, you'll see both solenoids opening and closed as commanded, fuel tank pressure kept stabilized. If one is commanded and the other isn't, or doesn't respond....there's a problem. I would expect a check engine light at some point.