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Another Common Issue?

2220 Views 9 Replies 7 Participants Last post by  justin1991
So this maybe a repeat of a very common threaded discussion. This is my second Wrangler, My first 4.0 never had this.
I have a P0455 Code, Large Leak in the evap system I have put on an after market gas cap cleared the code still came back on. So I went and bought a factory cap, Cleared the code and back on.. I get a fuel smell as well during my driving and start up, I have 84,000 miles on the jeep. Not sure if this is connected to the upper issues but if I drive over 60 Miles constant driving I will come back out couple hours or over night and try to start it but it doesn't start right away. Takes a few more seconds than normal. I Looked over the lines but didn't see any damaged lines or connections on any of the hoses. Lost and confused!
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No clue what the code is. The delayed starting after being off for a while is a device that keeps the fuel under pressure and not draining back into the tank. When it is bad the longer you go without starting it the further the fuel gets away from the engine. Then the fuel pump has to go for a while to pump it back.
Went thru that process for a year or so too. Ended up being the vac reservoir underneath the battery. It was ate up. My mechanic buddy fabbed me up his special fix and we relocated much more PO455. He is swapping my new .410 gears out for my new .456's or I would shoot you a pic. This weekend maybe.
I have had similar symptoms on my 02 Sport. I'm going to check my vac reservoir this weekend. If it's leaking then I will start there and not try and trace every single evap line.

Do you have any trouble with your HVAC blending?
The long crank after sitting for a while is called your fuel pressure regulator.
Yes on the AC, that was part of the same issue. Couldn't keep it in the vents it would go to the defrost vent. This fix did the trick.
Ok thanks guys, I also got some information on maybe being a purge valve. I will look at it tonight.
Justin, the code is just telling you that there is what it considers a large leak when the ECM commands the leak detection pump (LDP) to pressurize the fuel evap system.

The ecm decides whether to throw a code for a small leak or large leak dependent on how fast/long the pump has to operate.

Pretty simple system, ECM first checks the LDP for electrical/mechanical fault, if okay it then shuts the vent valve and turns on the pump to pressurize the evap system to check for leaks. No leaks no codes, leaks dependent on size determines the code.

Gas cap is often the problem, followed by cracked/ broken hoses to the various parts of the system, Evap canister leaking, vent valve stuck, and even a leak at the fuel tank.

A smoke test is used to check for the problem. Just a machine that pumps smoke under pressure through the system. Makes it real easy to find the problem, just look for the smoke leaking out.

If you don't want to spend the bucks on a smoke test, time to get dirty.
Flashlight, mirror, mark 8 eyeball. Go looking at every rubber hose in the evap and fuel system. Most of the time you'll find it right in the engine compartment, one or more of the hoses has dry rotted and split.

Should have an emissions label under the hood, shows all the vacuum lines and what they go to. Use it as a guide.

Funny I just had this code in my Colorado, turned out to be the vent valve.
Something like $129.00 for it from GM. Did a little checking and found the same valve is used on the Hummer 3, and it's 1/3 the cost. Wanna guess what I used?

One other thing, A/M gas caps are shall we say sometimes worse at leaking, especially the locking type then what you just took off.
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I just had same problem, was a bad weld on the filler tube. I had to get a smoke test to find it, I'd say after spending a lot of time looking for it, money well spent.
Havn't posted what the solution was, If any one is having close to my issue, not saying this is the answer, but I performed a smoke test cost me 55$ and happened to be the leak detection pump. Easy access behind the right rear wheel. Another way to test would be to clamp down the hose and run an evap test. if so it passes than should be that pump. Bad thing is couldn't find after market so factory part it was, 117$ no issues at this time!
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