Chasing an EVAP code

[buck91]

Working on my 2011 F150 5.0L and I've had a P0451 for a long time now. Sometimes it stays around, sometimes its intermittent. I have replaced the purge valve as well as the vapor canister solenoid. The Ford Easy Fill capless system is regularly cleaned with spray silicone and compressed air. Yet the fault continues. Today I noticed the addition of a P0443 as well.

Anyways, so I took out my laptop, elm tool and Forscan and did a little playing around. It seems like the tank holds pressure fairly well. When I command the solenoid open along with a good amount of purge valve duty cycle I can easily see negative 3-4kpa of tank pressure. If I close the solenoid it will hold that pressure for a few minutes. Interestingly, if I command a high duty cycle but leave the solenoid closed it will bring the fuel tank pressure to -2.x kpa. With the valve at 0% duty and the solenoid off it still is running about -1.6kpa fuel tank pressure which does not change when I open the fuel fill by inserting the easy fill funnel. Would this reading possibly be off enough to cause the DTC? It does seem like the canister solenoid is a bit sluggish and will let vacuum through to the tank pressure sensor sometimes, though.

 

[skyactiv]

You have a smoke machine?

 

[buck91]

You have a smoke machine?

I have a holiday smoke machine I've been meaning to rig a setup with but haven't really done that yet.

 

[TurboTravis]

I have recently proved that a smoke machine will not always find an EVAP leak. Long story short, I thoroughly troubleshot an EVAP leak on my 2005 Silverado. The leak was not apparent when using a smoke machine (yes, the proper valves were open/closed etc during the test), however I discovered it while applying low air pressure to the fuel tank. As I recall it was only 3-4 psi and I was easily able to locate the lock ring/seal leaking.

 

[BlueOvalFitter]

Working on my 2011 F150 5.0L and I've had a P0451 for a long time now. Sometimes it stays around, sometimes its intermittent. I have replaced the purge valve as well as the vapor canister solenoid. The Ford Easy Fill capless system is regularly cleaned with spray silicone and compressed air. Yet the fault continues. Today I noticed the addition of a P0443 as well.

Anyways, so I took out my laptop, elm tool and Forscan and did a little playing around. It seems like the tank holds pressure fairly well. When I command the solenoid open along with a good amount of purge valve duty cycle I can easily see negative 3-4kpa of tank pressure. If I close the solenoid it will hold that pressure for a few minutes. Interestingly, if I command a high duty cycle but leave the solenoid closed it will bring the fuel tank pressure to -2.x kpa. With the valve at 0% duty and the solenoid off it still is running about -1.6kpa fuel tank pressure which does not change when I open the fuel fill by inserting the easy fill funnel. Would this reading possibly be off enough to cause the DTC? It does seem like the canister solenoid is a bit sluggish and will let vacuum through to the tank pressure sensor sometimes, though.

I just recently had the same code (P0451) on my F-150. The Ford dealership my son works at had his shop foreman fix it. It was the FUEL VAPOR FILTER/FORD VAPOR SEPARATOR. It is a common failure on the F-150 years 2004-2014.
Part #F87Z-9B328-AB

 

[skyactiv]

I just recently had the same code (P0451) on my F-150. The Ford dealership my son works at had his shop foreman fix it. It was the FUEL VAPOR FILTER/FORD VAPOR SEPARATOR. It is a common failure on the F-150 years 2004-2014.
Part #F87Z-9B328-AB

That part is a cheap gamble worth taking.

 

[buck91]

I just recently had the same code (P0451) on my F-150. The Ford dealership my son works at had his shop foreman fix it. It was the FUEL VAPOR FILTER/FORD VAPOR SEPARATOR. It is a common failure on the F-150 years 2004-2014.
Part #F87Z-9B328-AB

Interesting. I would not have thought to replace that part. For $25 I'm gonna give it a try!