Jeep Liberty 2004 sport gas cap not sealing

no idea to be honest earlier jeeps had then at the front of the wing down below as i remember ?? newer one would i imagine be in the electrical box under the bonnet near the battery

If your gas cap is not sealing you will get check engine light because of low pressure. Make sure you turn the cap until it clicks, if you still have the issue after that replace the gas cap.

bad ground some where will cause this problem expecilly if its croded at battery termanal

Did they give you the error codes, or just tell you that it was the multiple engine misfire, evap and TPS? If they didn't give you the codes then I would take it to an autoparts store and have them read the exact codes. Replacing the heads because the valves are sticky is questionable in my opinion. Dealerships sometimes are quite unreasonable when it comes to replacement parts. Plus they seem more apt to take advantage of a KNG (Know Nothing Girl) than most shops.

I would like more information about the engine combustion cleaning that they performed!

You might also want to go to the http://www.jeepforum.com/ and post it there. They have multiple Jeep specialists that might be able to steer you in the right direction.

It is most likely a defective gas cap seal. They should have recommended this cheap replacement part first.

check small line returning from gas tank to evap cannister for leaks, cracked hose. Also check gas cap for seal.

U need to pull the fault code go to NAPA they do that for free. I will help you from there on.

By "Replace the gas cap", do you mean put it back on, or buy another one? If you fuel these trucks with the engine running, or don't tighten the gas cap, the light will come on. It will also come on when the seal in your gas cap goes bad. I have had to replace the gas cap on my jeep and dodge already. It fixed the problem both times.

Sorry your going to have to change the gas cap. You can try  spraying WD-40 to the rubber seal on the gas cap to get you some more months out of it, the seals get hard and don't seal any more. Good luck

Your problem is in the evaporative emission system which is designed to prevent the escape of fuel vapors from the fuel system. Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere. The light coming on can be caused by one of the following:

1. Defective or loose fuel cap
2. EVAP canister or hose cracked- not connected
3. Purge or vent solenoid defective
4. Vacuum leak at engine Government regulations require on-board testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. You have tried the easy fix, the gas cap. Finding the leak now will require special equipment and testing procedures, might be better left to a professional.

Please let me know if this information is helpful. Positive feedback is appreciated. Thank You!