Trying to get rid of P0442 - small Evap Leak

[RichardH]

Well, did some reading on the P0442, small Evap leak, a few folks (including the dealer said put a new gas cap on it and that should fix it. I didn't buy one from them.

It happened about a year ago and the new cap eliminated the code, but the gremlin is back.

I did replace with a new Stant at the time.

In the meantime I'm ordering:

https://www.fordpartsgiant.com/part...080&Filter=()&Location=engine/fuel_tank,,9030

Ford Part No.: XU5Z-9030-MA
Cap Assembly - Fuel Tank Filler


Base No. 9030
Part Description Cap Assy - Fuel Tank Filler
Manufacturer Ford. This genuine Ford part is guaranteed by Ford's factory warranty.

If this new cap is not the cure, any recommendations?

I was wondering if anyone did a bypass of the canister? I'm not sure yet if that is it, but if the bypass works I can R/R the can, or just remove and do a charcoal replacement and JB weld the container back together. I think there's also a method to blow compressed air on the downstream tube to agitate it up and 'clear' it out. If the can is the issue would a bypass be a good test???

I never overfill the gas tank, rarely go to the shut off on the pump, just guess how much to get close to a full tank - usually pretty close.

I have an inspection due by the end of June. They only plug their machine to the OBD and check tires, wipers, leak test on gas cap etc. No real 'inspection' or sniff test like CA.

Please let me know your thoughts.

 

[John Stephan]

Evap works off a purge valve and pressure sensor. You cant bypass without throwing codes. You need a good bidirectional scanner to monitor and actuate the valves manually. Or smoke the system and hope the leak is visible.

Basically the ecu sees that the tank pressure is changing without a duty cycle on the purge valve. Could.be a seal, could be the purge valve, could be a faulty sensor, could be a gas cap.

Sent from my SM-G950U using Tapatalk

 

[krakoosh]

Smoke test revealed mine to be the purge valve...bugged me for years. Always passed smog but kept throwing the code.

 

[thesavo]

In all my experience, the purge valve up front is the first thing to try. Mine was getting stuck and pulling it apart to test and dropping the hood fixed it.

A smoke test And a bidirectional scanner is better than a parts cannon.

You can use a brake bleeder pump as a vacuum test on the purge valve. It should hold vacuum at engine off.

Sent from my SM-N975U using Tapatalk

 

[thesavo]

Also, what year an engine size? Though, it shouldn't matter. According to Tasca parts, the purge valve is the same for 4.6 and 5.3, 1999-2006
Base part number is 9c915.
I would start by performing a vacuum hold test.

Disconnect the the engine size vacuum line and use a brake bleeder pump with a Guage.





Sent from my SM-N975U using Tapatalk

 

[RichardH]

Thanks for the info!

It's a '03 EB, 5.4, 2 wd

 

[Kevin Masters]

I bought all these.. new cap, purge value, new vacuum lines, fuel pump etc and I still get small evap leak. This what happens to me.. In the mornings if I drive for around 15 miles the evap light will come on but if I turn off the truck before than the light want get triggered. So I just turn off the car and back on before I leave the the house.. no evap code. I loose pressure overnight and for the life of me I can’t find the leak

 

[RichardH]

I bought all these.. new cap, purge value, new vacuum lines, fuel pump etc and I still get small evap leak. This what happens to me.. In the mornings if I drive for around 15 miles the evap light will come on but if I turn off the truck before than the light want get triggered. So I just turn off the car and back on before I leave the the house.. no evap code. I loose pressure overnight and for the life of me I can’t find the leak

Little gremlin.

The dealer (I was there for something else) actually told me to get a new cap that usually fixes it. In regards to the other EVAP components, I thought I would get a different code - P0446 or something other than the P0442 - small leak.

I believe it should be between the tank and the fill tube but I'm probably misinformed.

Thanks for your info - I'll wait for my OEM cap, drive it to see if MIL/CEL comes back then go to the next part, probably the vacuum lines/vent line. Hope they are not too hard to access. Any hints on replacing these items? I looked for a video but UTL.

Thanks,
Dick

 

[Kevin Masters]

Most of these are pretty easy to replace and can find on YouTube videos. The fuel tank(pump) isn’t as simple but can be done with a set of extra hands. there is a few videos on this as well on YouTube. Done mine with those videos. Saved thousands of dollars

 

[Hamfisted]

A P0442 leak is actually a pretty good leak in the system. Often a purge valve stuck open, or corrosion pin holes in the filler neck, or bad fuel cap. Do you have access to a mechanics smoke tester ?



https://www.ebay.com/itm/EVAP-Smoke...883925&hash=item41de9b5320:g:NNkAAOSw~4hbvI1l


Updated the eBay link.