Jeep threw me an engine light for another evap leak... Found a large and small leak from the gas cap, and the fuel tank o-ring. These were delt with. Getting yet another one, and I've gone through all my lines and couplings already. The lines are in excellent condition, and there's only one questionable coupling. This coupling is coming off the front of the intake manifold, looks dry and cracked.

Don't really know what else to do short of replacing the purge solenoid...? I'm not familiar with evap issues at all. Just enough to know they're a pain in the ***. How would I be able to tell if my purge solenoid is bad? and does anyone have a diagram of the monitored evap system, maybe I overlooked something?

98 XJ, small evap leak.

 

Here is a thorough explanation of how the system works, and what triggers the "evap leak" error:
http://autorepair.about.com/library/faqs/bl010h.htm

 

PO455 Evaporative emissions system gross leak - happened one week ago about 2 minutes of running after first start in the morning. I re-tightened my gas cap and cleared the code with my Actron scanner. This morning the same thing happened again. About 7 months ago I replaced my factory gas cap with an aftermarket locking cap. I'm going to put the old cap on, clear the code and see what happens. I'll report back on this thread if /when the light comes on again.

I have a steel portion of the purge line under the Jeep which was badly rusted when I bought the Jeep. I cleaned and painted that line and had no problem til now. If the light comes on again, I will replace that line and check / replace all the other purge lines from the fuel tank to the charcoal canister to the purge pump by the right side firewall under the hood. I'll also trace the grounds for the electrical part of the system and make sure they're clean. I Also believe there is a fuse for the purge pump and I'll check that also.

If all this fails (the cheap stuff) I'll have to bite the bullet and pay to have a smoke test done. Or figure out a way to use a bee smoker from my beekeeping days to do the smoke test.

 

I just had the smoke test done 2 weeks ago. The gas cap was replaced via dealership, and the o-ring on the fuel tank wasn't even tightend down. Fixed that as well. That steel line is also rusty on my rig. However there was no smoke coming from it. There was no smoke anywhere else than the previously mentioned areas.

 

Pic of location of the LDP.

 

most of the time an evap code is not a leak its an electrical problem i see it all the time at work you should test your ldp and purge valve the problem most likely one of them if u fixed all the leaks

 

I took a peek at the evap diagram shown in the DS firewall...

I found this to be apart of that system.



Obviously, it's cracked. Could this valve be throwing my PO0442 code? I have the part and intended to replace it while doing my valve cover gasket. I also located my LDP. How do I go about testing it?

 

That fitting in the pic is part of the CCV (continuous crankcase ventilation) system. you should repair or replace the "T", but I don't think it's causing PO0442 code.

Meanwhile, I replaced the gas cap on my 98 and so far, 24 hours later I haven't got another PO455. I checked the O'Reilly's cheap locking gas cap I had on there when my trouble started. There's a check valve in our caps that's supposed to allow air into the tank, but not out. The valve on my failed cap is clogged both ways, which would hinder the purge function on the LDP (leak detector pump). Hopefully this has solved my problem.

CEL came back on at Sunday morning start-up. Not the cap. Arrrggggh! Got to check all the lines next.

 

I know it's a part of the CCV system. However it's included on the Evaporation System diagram. After some research, I found these have thrown po0442 codes before. Or atleast they don't help trying to trouble shoot it.

After getting my codes cleared I have to take my Jeep around 60 miles or so. Takes me a while because I only work down the street and lately I haven't done much driving.

 

I filled my tank last week (very full) and smelled gas in the cabin. Crawled under the jeep and found fuel dripping down the side of the tank in the front where there is a dip where the fuel and vapor lines come out. I replaced the pump and gasket 1 year ago and everything was tight. This weekend I'll drop the tank part way to inspect the vapor line connection and the pump gasket. Yes, I now call the code Poo - 442.

 

Sorry to hear your EVAP code is back. Mine threw a P0445 code a few days ago out of the blue. No smell of gas. No noticeable symptoms. Got the code read at O'Reilly's and bought a new Stant non-locking gas cap. Very noticeable change in the tightness of the new cap. Old cap you would barely touch it and it popped out, even after clicking it four times to tighten.

Pulled the negative battery cable to reset. So far so good. No new code. But I've only driven it twenty miles or so. Will update if anything changes. Hopefully won't have to chase a leak like you are.

 

i'm having this issue also with my 2001 XJ, already replaced gas cup, but it feels just the same as the old one, ( very loose ), Will have to go to check hoses and stuff....

 

My 2001 cherokee sport haved same problem with evaporative codes. I finally solve the mistery when disconect the tubbing at the evap selenoid and presurize the line with only very little pounds. A leak revealed under the front door area, a craked coupler betwen the plastic and metal line. I solved it with 2 inch 5/16 gas tubbing. I also replace a dry coupling at the selenoid with 5/16 tub. codes cleared.

 

While installing a breaker for my 800 watt inverter, I disconnnected and re-connected the connector for the evaporative system (LDP) pump (see CCKen's diagram below). A week later, my check engine light went out and hasn't returned since. That was 2 months ago and the problem seems to have been solved. Dan Man said it's usually electrical problem below. good idea to refresh all connections in the system. I will give a heads-up on this thread if the problem returns.

 

Update: PO 455 and check engine light back in September. Also notice some fuel leaking from the top of the tank when I fill it. I'm due for inspection in February and must resolve the problem soon.

The only places it can be leaking are the rollover valve, fuel pump gasket, or the wire grommets on top of the fuel pump.

I learned that the rollover valve on the plastic tank is part of the gas tank and can't be replaced if it fails. A new plastic tank is $900. A junkyard tank may have the same problems. I'm thinking of getting a rollover valve and grommet made for a 96 XJ and cutting a hole to fit the new valve in my old tank. JB weld on the old valve to plug it up.

Another option is to buy an aluminum 31 gallon tank and skid plate kit for $900 and increase my range from 400 miles to 600 miles. $900 is a lot of money, even with the skid plate included. Any thoughts?