06 TJ 4.0 evap leak diagnosis

[blake711]

Hey guys I have an 06 TJ that had an evap leak when I got it. The main line to the evap canister was rubbed through. I was able to repair it with some large fuel line. The last couple weeks everytime my daughter parks in the garage its a fume fest. I got a smoke machine off amazon last night. From the fuel tank zero leaks. From the engine at the purge valve I see a small leak in my throttle body when its closed when going into the intake. When you actuate it to open like at throttle it seals off. Figure the shaft seals are bad or worn.

My main concern is I also found a large leak coming from what I believe is the vent or where the pump would pull air into the system. Video attached. Should this part of the evap canister have a check valve? Want to confirm this is my problem before dropping $200 on a canister.

 

[blake711]

So, from reading the service manual, it looks like the EVAP pump should be closed when the vehicle is off. This should prevent vapor or smoke from getting to the canister and being vented. Can anyone confirm that? I think I may have a faulty pump.

 

[Chris]

So, from reading the service manual, it looks like the EVAP pump should be closed when the vehicle is off. This should prevent vapor or smoke from getting to the canister and being vented. Can anyone confirm that? I think I may have a faulty pump.

The EVAP system should indeed keep the canister sealed when the vehicle is off. The pump has a check valve that should restrict airflow in one direction, preventing vapors from escaping when it's not in use. If you're seeing a significant leak from that area, it could be a sign that the pump or valve is malfunctioning.

Before you go ahead and replace the canister, it's worth checking the wiring and connectors to the pump, as sometimes corrosion or bad connections can lead to faulty operation. If you can, inspect the pump itself for cracks or signs of damage. Make sure to give the entire vent line a good look too (sometimes small holes can be overlooked)

Keep us posted on what you find!

 

[blake711]

Chris thanks for the reply. The only place I saw smoke was from that vent on the canister. Makes me think its coming strait through the valve. I went ahead and ordered a dorman against my better judgement. I may go ahead and pull it off again and disconnect that pump to confirm its going strait though it. If so I Can block back side of pump and smoke test it again also.

I also read in the manual how you can test the pump with a 12v test light. So I may try that also to confirm its got good power. The connector was clean and no corrosion when I removed it.

 

[Chris]

Chris thanks for the reply. The only place I saw smoke was from that vent on the canister. Makes me think its coming strait through the valve. I went ahead and ordered a dorman against my better judgement. I may go ahead and pull it off again and disconnect that pump to confirm its going strait though it. If so I Can block back side of pump and smoke test it again also.

I also read in the manual how you can test the pump with a 12v test light. So I may try that also to confirm its got good power. The connector was clean and no corrosion when I removed it.

If the smoke is coming straight through the valve, that definitely points towards the pump or the check valve being the issue. By disconnecting the pump and doing a smoke test, you'll be able to determine if the leak is indeed coming from there. Blocking the back side of the pump should help isolate the problem further.

Testing the pump with a 12V test light is a great idea too. It’s worth confirming that it's getting power when it should be working. Since the connector is clean, it’s less likely to be the culprit, but it's always good to eliminate possibilities.

Hopefully, the new Dorman canister will solve your issue!

 

[macleanflood]

So on my 97 my evap solenoid failed. It was full of charcoal from the cannister.

When the Jeep starts it's in open loop and using default tables. When it gets to closed loop the solenoid will start clicking. You can put a screwdriver on it to your ear and listen.

-Mac