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post #1 of 15 Old 09-27-2019, 07:16 AM Thread Starter
bizzs
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Need help locating part

Hi guys, I have a 2005 Cherokee Laredo 3.7l I have the dreaded p0456 code. I did a smoke test and noticed smoke escaping out of what appears to be a filter that is mounted on the gas fill neck. The filter has a hose running to the canister and connects into the vapor leak detection pump. If the filter is faulty, would it allow the smoke to escape out or could it be the vapor leak detection pump being faulty?

I checked Mopar's website and it does not list the filter. It only lists the entire filler neck which is discontinued. The leak detector pump are readily available.

Does anyone know where I can get just that filter? I found the entire neck on google but it is priced at 500.00 and I do not want to spend that type of money on a 14 yr old vehicle.

Thanks
bizzs

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post #2 of 15 Old 09-27-2019, 08:23 AM
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Are you looking for the vapor canister? https://www.rockauto.com/en/catalog/...+canister,5180

5 and counting :05 WK 5.7 HEMI
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post #3 of 15 Old 09-27-2019, 10:01 AM Thread Starter
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No, that is not it. There is a hose that goes from a valve on the canister and travels up the fill neck to a filter that is mounted on the fill neck. If you look on Chryslers parts page you will see it above part "4".

https://store.mopar.com/2005-jeep-gr...nents-WA05620/

Could the leak detector pump be faulty? I was under the impression from reading that the evap system was sealed and should have no air leaks. The smoke is very obvious coming out at the top of the filter.

THANKS
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post #4 of 15 Old 09-27-2019, 12:08 PM
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Quote:
Originally Posted by bizzs View Post
No, that is not it. There is a hose that goes from a valve on the canister and travels up the fill neck to a filter that is mounted on the fill neck. If you look on Chryslers parts page you will see it above part "4".

https://store.mopar.com/2005-jeep-gr...nents-WA05620/

Could the leak detector pump be faulty? I was under the impression from reading that the evap system was sealed and should have no air leaks. The smoke is very obvious coming out at the top of the filter.

THANKS
bizzs
If you have the gas cap off, I think you are supposed to see smoke there . Then replace the gas cap and keep pumping smoke for 60 sec to check for leaks.

Could be the vacuum leak detection pump or more likely the purge valve solenoid as I remember those being an issue at one time. Gas cap as well if you haven't changed that .

5 and counting :05 WK 5.7 HEMI
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post #5 of 15 Old 09-27-2019, 12:20 PM
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Are you SURE of your troubleshoot method ?

IIRC a bi directional scanner is needed.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #6 of 15 Old 09-27-2019, 12:43 PM Thread Starter
bizzs
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Quote:
Originally Posted by jtec View Post
Are you SURE of your troubleshoot method ?

IIRC a bi directional scanner is needed.
I am not sure of the method procedure. Can you advise? I have a snap on solus and it passed all of the evap tests. I am getting a P0456 (small leak) and my solus troubleshooter recommends new purge valve or a smoke test for cracked lines. I replaced the purge valve and code set off after the PCM relearning process. The code appeared again when vehicle was cold started in morning (60f).

I visually checked all lines and do not see any cracks. I disconnected the purge valve near the battery and I am running the smoke through the port that leads to the gas tank. I see smoke coming out of that filter only, not any of the other lines. There is no smoke leaking around the "new' gas cap either.

Do I have to disconnect that rubber line and plug the hose to that filter on the fill neck? Any recommendations? This is my first smoke test on a jeep and there is no video's showing how this is done, but a lot of write ups.

Thanks
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post #7 of 15 Old 09-27-2019, 04:33 PM
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attachment
Attached Files
File Type: pdf P0456 (1).pdf (26.0 KB, 6 views)

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #8 of 15 Old 09-27-2019, 06:52 PM Thread Starter
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Thanks for that information. I plugged the filter, disconnected the purge valve and ran smoke test. No signs of smoke leaking from the top of the gas tank, or any of the lines or elbows, nor the new gas cap.

I connected the smoke machine to the other vacuum line coming from the purge solenoid that leads to the throttle body. There is smoke coming from what I think is the throttle position sensor. This sensor sits above the iac. Is there an o ring seal around that sensor? Would the tps leaking cause a p0456 dtc?

I ran an evap test using the solus and everything passed. There were no major leaks found.

I noticed that after the drive cycle is completed the p0456 reappears during the first cold start. Could the leak detector pump be faulty?

I am a fairly decent mechanic and I am running out of ideas. Guessing what part is bad is getting expensive.

Any help would be appreciated because this p0456 is driving me nuts.

Thanks
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post #9 of 15 Old 09-28-2019, 02:02 PM Thread Starter
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Anyone have recommendations?
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post #10 of 15 Old 09-29-2019, 01:16 PM
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Replace the Leak Detection Pump (LDP, ISIM) And make sure cap is OE (not aftermarket). The switch in the LDP goes bad. Also, you can verify LDP switch wiring by undoing connector, then look at live data, look for “Switch open/closed” You should see value change with connector unplugged or shorted (with a jumper wire). If no change, you have a wiring issue.

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post #11 of 15 Old 09-29-2019, 04:10 PM Thread Starter
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Originally Posted by YJ325i View Post
Replace the Leak Detection Pump (LDP, ISIM) And make sure cap is OE (not aftermarket). The switch in the LDP goes bad. Also, you can verify LDP switch wiring by undoing connector, then look at live data, look for “Switch open/closed” You should see value change with connector unplugged or shorted (with a jumper wire). If no change, you have a wiring issue.
Thanks for the info. My snap on has the bidirectional capabilities and I can control the ldp. It seems to be functioning correctly. I removed it from the truck and can hear it clicking and can see the diaphram moving in and out. The O ring looks good. The gas cap and purge valve are new and are factory Mopar.

I ran another smoke test and no leaks detected. I disassembled all of the evap connections and put a little bit of lithium grease around the connection to see if it helps out. I put everything back together and I am in the process of performing the drive cycle. I put 90 miles on and no check engine light yet. I guess the big test will be in the morning when I do the first cold start up. I will post the freeze frame results of the dct if the pcm sets the code off again. Maybe this will give a better idea of why this p0456 is happening.

Thanks for your help,
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post #12 of 15 Old 10-05-2019, 04:47 PM Thread Starter
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P0456 help

After 160 miles, P0456 appeared again. I built a nice smoke machine and it smokes pretty good. I ran about 1 pound of pressure in the evap system and I noticed a lot of smoke coming from the gas cap. This is a brand new dealership Mopar gas cap and I do not know why it is leaking. Is there something I can add to help seal this new cap?

I can hear hissing sound above the gas tank when air is pumped into the evap system. I added smoke and I did notice a little sign of smoke above the gas tank but it stopped. I can still hear the air hissing though. Is there a relief valve on top of the gas tank where the air is escaping or is this evap system supposed to be completely sealed? When the evap system is pressurized with air, I can hear the suction release when I remove the gas cap.

Furthermore, Can I drop the tank down enough to evaluate the hissing without removing any of the evap and fuel connections?

Anyone have thoughts about this and my questions? This P0456 is a real beach to figure out and I am running out of ideas.

Thanks
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post #13 of 15 Old 10-07-2019, 12:43 PM
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Not sure how you are controlling the Leak Detection Pump with a scan tool. Its just a switch. 4891524AA $40 from amazon. Really, we've only had good luck with OE evap parts on Chrysler, but its worth a shot. I work on a lot of these and 95% of the time its the LDP. (electric fault, not leak). Also, how much air pressure (psi) are you using to "smoke" system. Should not be shop air pressure, usually around 100 psi, our smoke machine turns it down a lot, somewhere around 1-5 psi.

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post #14 of 15 Old 10-07-2019, 02:05 PM Thread Starter
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Thanks for the reply YJ325i. My solus has a function capabilities and it permits me to control the leak detection pump as well as other components such as the purge solenoid too.

I ordered another Mopar leak detection pump and it should be delivered today.

The smoke machine I built is regulated and the pressure is set for 1 pound but it can be adjusted up to 2 pounds tops. It actually works great and not a bad investment for 20.00 worth of parts. The smoke if thick and can be instantly seen.

Thanks,
bizzs
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post #15 of 15 Old 10-15-2019, 09:39 AM Thread Starter
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UPDATE UPDATE FIXED I THINK

I received a new leak detection pump and changed it only having the same results. The CEL came back on after the drive cycle was completed. I thought that there was no way that both new Chrysler pumps were bad so I pulled down the tank. I pumped smoke into the gas tank and no smoke was seen exiting. I pumped less then a pound of compressed air through the tank and applied soapy water to all the rubber hoses while wiggling them around. I could not believe that I found a slight bubble in one of those rubber hoses. It was the size of a pin hole. The rest of the hose was not dry rotted so I believe that this must of been an ongoing problem with this car since it was new. I believe the prior owner had the code reset before she sold it to me. I replaced the hose and put the first leak detection pump back on and reset code. I filled the gas tank up to 3/4 full and drove it for 450 miles. No codes have appeared yet. The CEL usually appears between 70 and 100 miles when the drive cycle is complete so I believe this problem is hopefully resolved.

Bottom line: The P0456 is a very difficult time consuming fix. The evap system is not complex, but it is a time consuming process to find such a small leak. I had the proper tools, including my bidirectional snap on scanner and my dyi smoke machine. I was fooled when the scan tool reported that all tests had passed so my next step was to start replacing evap parts. This was a costly process of elimination theory but I had no choice but to fix this problem because of future emission testing. The end result was the old soapy water trick found a pin hole leak. After I replaced the hose, I determined that the original leak detection pump was faulty too. I was fortunate that my local dealer accepted a return on one of the new pumps. I know this is an older Cherokee, but I hope that this may help others in the future, and I am keeping my fingers crossed that no P0456 reappears.

Thanks
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