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.

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[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.

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[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.





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[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.

 

[RichardH]

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/Automotive...413072?hash=item5da8d3d390:g:L~YAAOSwzQpev5m1

Interesting. The literal definition of the code says "small leak" vs other codes. Thanks for the info.

I do not have access to a smoke system, but with the link and at $40 bucks, should direct me on the proper course...

Again - thanks,
Dick

 

[thesavo]

Wow, $40 for a smoke machine? For that price I would buy one preemptively.

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[RichardH]

Wow, $40 for a smoke machine? For that price I would buy one preemptively.

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Sure and you can charge you most annoying friend $20 twice for the test and the part is free!

 

[Kevin Masters]

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/Automotive...413072?hash=item5da8d3d390:g:L~YAAOSwzQpev5m1

Link doesn’t work.. can you update it?

 

[riphip]

Link was removed by ebay. EBay said was Chinese scam. Got my money back through PayPal.

 

[Hamfisted]

Link was removed by ebay. EBay said was Chinese scam. Got my money back through PayPal.

Wow, that's really crappy. I hadn't bought one in over ten years, I just thought maybe the price had come down on them, or that model. Sorry about that. I updated the link to another seller that must be more legit.


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

 

[tvlunn]

I'll share some information which may be helpful:

1) I'm not sure of your particular model, but I have a 1998 Expedition which I purchased new and has been well maintained through the years. It has a 5.4 engine. Earlier this year I also received a P0442 engine code. I too was hopeful the gas cap was the culprit and purchased a new OEM cap. That did NOT correct the issue!

2) After visually inspecting what EVAP system hoses and tubing could be easily accessed, I could not visually detect any type crack, pinhole or loose connection. I then checked for proper operation of the purge solenoid and vapor canister vent solenoid and found they were functioning and sealing properly.

3) I then realized, as I had already been informed, a smoke machine was likely the only way to detect the cause of the code. So, I purchased a smoke machine. Once I connected the smoke machine to the EVAP system, it only took about 20 minutes to see there was smoke leaking from somewhere on the TOP of the fuel tank …………...…. not what I wanted because that meant, well you know, remove the tank!

4) Once I dropped the tank, I connected the smoke machine to the fuel tank itself and could then easily see where a SMALL amount of smoke was escaping. It was escaping from around the front vapor valve. Close inspection showed a VERY SMALL crack in the plastic or composite fuel tank, just below the hose nipple on the vapor valve.

5) These composite fuel tanks for the older Expeditions are now obsolete and can not be purchased. There was no used tank to be found locally, so I elected to try and repair the crack with JB Weld. That was about 3.5 months ago, and so far, the JB Weld is holding perfectly!

Attached is a photo of the repair. And by the way, the two vapor valves on the composite tank are not replaceable as they are sonic welded in place.

So, unless one of your two solenoids are defective, you have a bad fuel cap, or a leak that can be easily spotted, the use of a smoke machine will likely be required.​

Hope this is helpful!

 

[RichardH]

I'll share some information which may be helpful:

1) I'm not sure of your particular model, but I have a 1998 Expedition which I purchased new and has been well maintained through the years. It has a 5.4 engine. Earlier this year I also received a P0442 engine code. I too was hopeful the gas cap was the culprit and purchased a new OEM cap. That did NOT correct the issue!

2) After visually inspecting what EVAP system hoses and tubing could be easily accessed, I could not visually detect any type crack, pinhole or loose connection. I then checked for proper operation of the purge solenoid and vapor canister vent solenoid and found they were functioning and sealing properly.

3) I then realized, as I had already been informed, a smoke machine was likely the only way to detect the cause of the code. So, I purchased a smoke machine. Once I connected the smoke machine to the EVAP system, it only took about 20 minutes to see there was smoke leaking from somewhere on the TOP of the fuel tank …………...…. not what I wanted because that meant, well you know, remove the tank!

4) Once I dropped the tank, I connected the smoke machine to the fuel tank itself and could then easily see where a SMALL amount of smoke was escaping. It was escaping from around the front vapor valve. Close inspection showed a VERY SMALL crack in the plastic or composite fuel tank, just below the hose nipple on the vapor valve.

5) These composite fuel tanks for the older Expeditions are now obsolete and can not be purchased. There was no used tank to be found locally, so I elected to try and repair the crack with JB Weld. That was about 3.5 months ago, and so far, the JB Weld is holding perfectly!

Attached is a photo of the repair. And by the way, the two vapor valves on the composite tank are not replaceable as they are sonic welded in place.

So, unless one of your two solenoids are defective, you have a bad fuel cap, or a leak that can be easily spotted, the use of a smoke machine will likely be required.​

Hope this is helpful!


View attachment 36183

tvlunn, that is great information - BTW, I have a 2003 EB 5.4 2 wd. 150k miles, runs great. When I bump it into N at red lamp, I can't even feel the engine running - it;'s so smooth! Very small difference in D, but I believe that's normal.

And I am always open to other's experience with this in an effort to cure the issue.

$155 is sort of steep for me until I get back into FT work, possibly in about 3 weeks. I will check with a friend to see if he has one. That seems like the best start to dx'ing the problem.

Here is another quick question (hopefully).

I have a regular not super high end OBDii scanner. It's not showing any stored codes but is showing pending codes w/ P0442. Again, no stored codes and no MIL/CEL lamp illuminated. On checking the live or KOEO data, is reads MIL_DIST 0km/mi. Does that mean I have driven enough miles since erasing codes? It used to show P1000 - must drive more miles.

If this is good to go (GTG) and a pending code won't trigger a FAIL at inspection, it'll be a beeline after I get some feedback. I'm also going to call a different shop than I plan on getting the inspection to see what they say tomorrow AM, but would also appreciate any info from the brain trust here at this forum.

TIA,
Dick

 

[Hamfisted]

Check with some of your local auto parts stores for the smoke machine. I know my local NAPA shop down here has one they rent out.

 

[RichardH]

Check with some of your local auto parts stores for the smoke machine. I know my local NAPA shop down here has one they rent out.

Most definitely! I had that thought in mind to check w/ Auto Zone this morning, I'll look for a local Napa - thanks. Was also looking at Amazon this morning, those machines are kind of expensive...

Dick