P0455 EVAP GROSS LEAK - Need Help 2001 XJ

Okay, so I've been chasing this thing down for longer than I'd like to admit.

I took my 2001 XJ to a shop to have them check out the Jeep to see if they could find this mystery gremlin. I had them replace the lines going from the charcoal box and myself replaced the Leak Detection Pump at their recommendation.

Code came back today.

I've replaced the gas cap with a MOPAR cap. They had smoke tested and said it was for sure the LDP, but replaced that and it's obviously not fixed. I can't figure this damn thing out. I don't know where else to look.

Pissing me off though! Any help is appreciated.

I may be stating the obvious, but it sounds like all that's left is the hoses. They get dry and crack. On my daughter's TJ it was the large hose coming out of the pump. Also just for kicks, check the fuel vapor vent filter. It's real easy. Pop the cap off, pull out the filter and blow it out with compressed air. Looks like a giant 35mm film canister. This won't be the source of your problem, but my daughter's was almost completely clogged...

Original_MudButt said:

I may be stating the obvious, but it sounds like all that's left is the hoses. They get dry and crack. On my daughter's TJ it was the large hose coming out of the pump. Also just for kicks, check the fuel vapor vent filter. It's real easy. Pop the cap off, pull out the filter and blow it out with compressed air. Looks like a giant 35mm film canister. This won't be the source of your problem, but my daughter's was almost completely clogged...

Click to expand...

Changed that filter awhile back. I think I might have found the culprit in the hose that goes from the LDP to intake manifold. I'll have to see. Every thing else looks pretty good and all the hoses running to the back canister were replaced recently.

I hate this stupid emissions crap. Annoying.

Another possibility is the fuel filler hose and vent, although
that should have shown up with the smoke test.

You might try snugging up the clamps a bit to see if that
helps. Won't cost anything...

Okay replaced a bad line yesterday and drove it around for a bit. Started up this morning and got a rough start and CEL popped on with the same code plus P0301 Cylinder 1 Misfire. I don't know what the hell this is and I'm at this point at a loss.

Need to solve this, because I'm tired of looking at this stupid damn light and my Jeep running like shit.

Thanks guys. A little bit irritated about this damn thing.

LazersGoPEWPEW said:

Okay, so I've been chasing this thing down for longer than I'd like to admit.

I took my 2001 XJ to a shop to have them check out the Jeep to see if they could find this mystery gremlin. I had them replace the lines going from the charcoal box and myself replaced the Leak Detection Pump at their recommendation.

Code came back today.

I've replaced the gas cap with a MOPAR cap. They had smoke tested and said it was for sure the LDP, but replaced that and it's obviously not fixed. I can't figure this damn thing out. I don't know where else to look.

Pissing me off though! Any help is appreciated.

Click to expand...

If you paid a shop to diagnose the problem, and they diagnosed it incorrectly, then take it back or get your money back. Any legitimate repair shop will accommodate you. Curious to know what shop you took it to as I am in the la area as well.

I would ask also, did they apply vacuum to the diaphragm solenoid on the leak detection pump and actuate the solenoid to pull the vent valve closed in the LDP ? If they did not, likely the leak detection pump was misdiagnosed.

hexdmy said:

If you paid a shop to diagnose the problem, and they diagnosed it incorrectly, then take it back or get your money back. Any legitimate repair shop will accommodate you. Curious to know what shop you took it to as I am in the la area as well.

I would ask also, did they apply vacuum to the diaphragm solenoid on the leak detection pump and actuate the solenoid to pull the vent valve closed in the LDP ? If they did not, likely the leak detection pump was misdiagnosed.

Click to expand...

Took it back to the shop and they smoketested again for free.

Nothing came up. Replaced solenoid, still getting code, will replace fuel pump assembly once my fuel drains down some more.

I suppose it could be the charcoal cannister, but I need to replace the fuel pump anyways.

I had this problem on my 01 XJ... I followed the hard plastic lines from the pump back to the canister, inch by inch... as the lines go across the firewall to the driver side and down, the hard plastic line switches to a flexible rubber fuel line, and then switches back to a hard plastic line that runs along the lower drivers side of the jeep back to the canister. My leak was in the rubber section. I squeezed the rubber line firmly and it split right open it was so dried out and brittle. If I remember correctly there is more than one line. Then a few years later my jeep developed another leak in the rubber fittings at the end of the hard plastic line where it connects to the canister.