Gas Cap Replacement Question (PO455 & PO442) - JeepForum.com

 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 21 Old 03-01-2016, 10:24 PM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
Gas Cap Replacement Question (PO455 & PO442)

I have PO442 pop up about 2-3 times a year. Given the mileage on my WJ, the gas cap doesn't feel snug anymore. Usually, i torque the cap on again, clear the code and I'm fine for another 5000 miles.

Today I got the usual PO442 and a new PO455. I traced my vacuum lines tonight and can't see any breaks or tears in the hoses. I have an 01 and my canister is easily observed in the engine bay. My best guess is the gas cap is just getting worse, hence the "large leak" PO455.

My question is two fold:

1. Is gas cap replacement the best first step given there is nothing glaringly broken?

2. Is it the cap that wears out or does the filler neck in the body also wear out? Do i replace just the cap or both?

Thanks folks.

sdg3205 is offline  
Sponsored Links
Advertisement
 
post #2 of 21 Old 03-01-2016, 10:51 PM
2GPS4ME
Registered User
1998 TJ Wrangler 
 
Join Date: Jan 2008
Location: 44.1N, 103.2W
Posts: 858
Garage
Forget about the fuel cap. They're not as integral to evap systems as way too many people are leading to believe. You most likely have a leak in one or more lines at the evap canister. Behind driver's side rear quarter panel.


WJ (WIFE JEEP) PROJECT COMING SOON
2GPS4ME is offline  
post #3 of 21 Old 03-01-2016, 10:57 PM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
Quote:
Originally Posted by 2GPS4ME View Post
You most likely have a leak in one or more lines at the evap canister. Behind driver's side rear quarter panel.
As i mentioned, my canister is right in the engine bay and all the lines to it and to the manifold and around the engine bay are fine. Noting out of place around the LDP either.
sdg3205 is offline  
post #4 of 21 Old 03-02-2016, 03:12 AM
ace4usmc
Registered User
2004 WJ 
 
Join Date: Jul 2011
Location: Gainesville
Posts: 121
Even though your evap canister is in the engine bay there are still lines that go back to to the fuel tank.
2GPS4ME likes this.
ace4usmc is offline  
post #5 of 21 Old 03-02-2016, 07:34 AM
lincolnshibuya
Registered User
2000 WJ 
 
Join Date: Dec 2014
Location: Kansas City
Posts: 319
if you can't see the crack or leak, a smoke test will verify.

http://facebook.com/diyjeepwj
use "https"
lincolnshibuya is offline  
post #6 of 21 Old 03-02-2016, 08:31 AM
Double E
2000 Laredo V8
 
Double E's Avatar
2000 WJ 
 
Join Date: Oct 2003
Location: Raleigh, NC
Posts: 4,720
+1 on the issue being a small crack in one of the hoses. I finally found mine and those 2 codes cleared not to return.
My 04 has the majority of the plumbing in the driver's side rear and it took a bit to find...but there it was.

2000 Laredo 4.7L Selec-Trac. 177K miles, Leather, 245 tires, tow package, crappy CD changer, full size spare, roof cross-rails & sunroof.
Changes & fixes: Rear Addco sway bar & greasble bushings, upgraded headlights, upgraded tail lights, new hood struts (replaced 2X), new rear hatchglass struts, new radiator (replaced 3X), new oil pressure sending unit (replaced 4X), 2 new speed sensors, 2 new door lock actuators, new ignition key cylinder, chrome front tow hooks, Mobil 1 Synthetic 5/30, Purolator Pure One oil filter, EBC slotted & dimpled rotors, EBC Greenstuff pads, new front shocks (replaced 3X), new rear shocks (replaced 2X), new IRO steering stabilizer, new timing chain cover, new water pump, thermostat, new thermostat housing, new high pressure power steering hose, Michelin-X radials, new sunroof assembly, new single-piece lug nuts, new exhaust manifold studs & gasket on driver's side, new Durango alternator. Jeepforum.com sticker, Visit cobaltboatsforum.com when you can!
Double E is offline  
post #7 of 21 Old 03-03-2016, 10:38 PM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
I'm not sure if it will make an ounce of difference, but i cleared the codes then wrapped the hell out of the gas cap with teflon tape tonight and tightened it up really well. It's too late to go out for a spin now so I'll see what pops up on the commute tomorrow. I keep my scanner in the seat back.

Recently, the two codes come back within a few minutes every start up so we'll see if this helps prove or disprove the "bad cap" theory. I don't want to buy a new cap if this aint the problem.

I took another good look tonight of the system and still couldn't find anything, so if the cap-wrap (ha!) fails to yield new results I'll have to look into a smoke test.
sdg3205 is offline  
post #8 of 21 Old 03-06-2016, 09:08 PM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
Teflon tape on the cap did sweet FA. Still getting the codes.

Tonight i decided to start at the filler neck and work towards the tank. There are 3 hoses; the large fill hose, a smaller breather hose also connected to the filler neck AND a third smaller hose with what looks like a check valve on the butt end. Could this check valve be bad? Whats the purpose of this hose? Does it vent post-canister air to atmosphere?

Also, there was a TON of caked on dirt, almost like someone had coated the 3 hoses with axle grease and they had collected road debris and dirt for 15 years. I literally scrapped it off gently with a dry wall paddle and vacuumed a huge pile of dirt off the floor.
sdg3205 is offline  
post #9 of 21 Old 03-07-2016, 09:55 AM
Brimstone
Registered User
2000 TJ Wrangler 
 
Join Date: Mar 2012
Location: Colorado Springs
Posts: 477
I had an Evap system code come up around Christmas, I don't remember what the code number was. I believe it was a large Evap system leak (and I had a pending code for slight evap system leak).

Replacing the gas cap took care of it for me. Neither code has been back since.

2004 WJ Overland 4.7HO
2000 TJ Sport 4.0L
Brimstone is offline  
post #10 of 21 Old 03-07-2016, 11:51 AM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
Yeah, I probably need one anyway but I'd like to run some tests first.

Can anyone confirm the 3 hoses at the filler neck? Anyone have a picture?
sdg3205 is offline  
post #11 of 21 Old 03-13-2016, 12:53 PM Thread Starter
sdg3205
Registered User
2001 WJ 
 
Join Date: Jun 2011
Location: Surrey
Posts: 690
Since wrapping the gas cap in teflon tape my PO455 (large leak) has disappeared and been replaced by a PO456 (very small leak) and a PO442 (small leak), so maybe I'm on the right track. Why thought would the system throw two small leak codes and not just one? would it start with a PO456 and then upgrade it to a PO442 when the eval leak got a little bigger?
sdg3205 is offline  
post #12 of 21 Old 03-14-2016, 10:12 AM
Brimstone
Registered User
2000 TJ Wrangler 
 
Join Date: Mar 2012
Location: Colorado Springs
Posts: 477
Not sure, like I said though I had an active large leak and a pending small leak code at the same time.

Wrapping the cap threads may help, but you may notice that the inside of the cap has a small valve assembly in the center. There is no way to fix that if it is also leaking. I would seriously just try a new cap. I got a good replacement one at NAPA, or I would recommend an OEM one. I wouldn't guarantee one of the generic Stant ones you find at most parts stores will work properly.

2004 WJ Overland 4.7HO
2000 TJ Sport 4.0L
Brimstone is offline  
post #13 of 21 Old 03-14-2016, 03:33 PM
cvnpguy82
Registered User
 
Join Date: Jan 2016
Location: Stow
Posts: 19
Mine failed an emissions test a couple of weeks ago because of a P0455. No light was on, so I was a little surprised.

I had a couple guys tell me the gas caps go bad so I decided what the hell and bought a new one at Autozone. I put the new cap in, cleared the code with their scanner, and it has not come back so far (3 days ago). I'm thinking there may be a "vent" of some sort actually inside the cap that fails, not just the gasket.

It only cost $13, so it might be worth a try.
cvnpguy82 is offline  
post #14 of 21 Old 03-14-2016, 04:31 PM
JS97ZJ
Registered User
2004 WJ 
 
Join Date: Dec 2009
Location: Dingmans Ferry
Posts: 2,285
Stant products are the best in after market replacements. I wouldn't trust anything else except OEM. (Gas caps and thermostats)
JS97ZJ is offline  
post #15 of 21 Old 03-14-2016, 05:31 PM
losttech
Web Wheeler
 
losttech's Avatar
2000 WJ 
 
Join Date: Jun 2013
Posts: 2,554
Quote:
Originally Posted by JS97ZJ View Post
Stant products are the best in after market replacements. I wouldn't trust anything else except OEM. (Gas caps and thermostats)
I did a Stant 10591 Locking Fuel Cap 4 years ago no issues since then and no problems with lock.
I only got lock because lots of kids out here and gas was 4 bucks a gallon at the time didn't want it siphoned or something poured in tank.
losttech is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome