99 4.0 and the dreaded EVAP system leak code
- Thread starter any4xx
- Start date
Unsure exactly WHEN it’s supposed to click. I could never tell if either the old one or the replacement ever made clicking noises. Is it supposed to be a constant event?
It’s the fuel pump seal,you won’t be able to see it leaking unless you either have the tank down or an access panel.it has to be really tight.
usually what happens in the EVAP system is the bag ruptures in the EVAP cannister and the charcoal contaminates the purge valve. It's usually best to replace both at the same time. Many times people will replace the purge valve and when that doesn't solve the problem they replace the cannister. But the new purge valve is already contaminated with charcoal and the problem still persist. So they start chasing other things. Also its best to blow out the line between the cannister and purge valve in case there's any charcoal in it .
I was ready to address this probability yet again. But again, I’ve had the tank off and I can literally turn the fuel tank into a balloon with the smoke machine. I’ve tested it both as a part of the whole system and with the tank off and treated as a sole component. Last time you steered me in this direction I removed the fuel pump, greased everything up, and reinstalled it with 100% certainty that there is no leak at the seal. When I started again today my intention was to go right back to the pump as step-1. Dropping the tank down enough to check the sealing area is pretty easy. There’s no leak there.
But back to the purge solenoid: can anyone tell me just when and/or how often I’m supposed to be able to feel hear it cycling? I just checked it again and after starting the Jeep cold and feeling/listening for a few minutes, nothing ever clicked.
this thread might help you some. I'm not sure if the valve will click all the time or only when it's doing the test. I would think it would come on only when testing, but not sure.
https://wranglertjforum.com/threads/2001-tj-wont-pass-smog-inspection.60182/
https://wranglertjforum.com/threads/2001-tj-wont-pass-smog-inspection.60182/
Well Folks…. At the risk of jinxing myself, the problem appears to finally be solved. To recap, I’ve previously tested everything for leaks and replaced the electrical components. The problem persisted. I again replaced the test pump and that didn’t change anything. I again replaced the purge solenoid and it’s now gone two full weeks without throwing the large leak code. So I’m guessing that the original and the first replacement solenoids were bad. I absolutely HATE the parts-cannon approach but I was at my wits end with this issue. I was previously asked if the solenoid was clicking. I never felt it doing anything. But to be fair I haven’t felt my new one clicking either.
So, again I thank all of you who took the time to respond.
So, again I thank all of you who took the time to respond.
Aaaaand… as expected, I did jinx myself. This morning the Check Engine light came back on. HOWEVER, the code has changed. Previously it had consistently been P0455, Large EVAP Leak. Now it is reading, P0441, Incorrect Purge Flow. I guess I should be happy to have at least changed the malfunction parameter.
Time for more research…
Time for more research…
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