I drove the van then came back and pulled the vent line out of the purge valve connector. It had vacuum while running. Pulled the harness connector off and the valve closed. I have nothing to tell me when it is to be open but should be closed when the engine is off or the LDP will call it a leak and trigger a CEL. Happed today too.

Also while messing with it today I found that if I revved the engine to 3000 rpm the fuel needle and dte dropped like it does while driving. Each time I lost over 1/8 tank at the needle. Let off and it would slowly recover. Pull the fuel cap and it would quickly recover.

I pulled the drivers side rear inner fender to see where this third line went next to the fuel filler and filler vent line. Its another assy and all the lines join up there and still sealed behind the fuel cap.

I have yet to identify any vent that will release built up vacuum in the fuel tank. The engine seems to pull the tank into a vacuum situation is all I can figure so far and it snowballs maybe with the fuel pump. Also found that the fuel system is returnless at the fuel rail. The only return I found was at the fuel filter. I really dont know what the hell is happening honestly. Im going to start again tomorrow and chase some more. I have two lines at the rear of the charcoal cannister that I want to find out where they go.

Thank you for the help!

 

Here’s a diagram for the EVAP system. I’m still reading through the system operation for what is supposed to happen and when. My understanding of the LDP has always been that it doesn’t check for leaks until after engine shut down, but I’m not sure that’s the case with your van (this was still in the relatively early years of OBD2 and LDP so the operation could have changed since then).

I still think this is a venting issue, it’s just a question of what. I’ll post more details once I’ve finished the reading.

 

I bet its this assy in the drivers rear fenderwell. Both tank vents go to this and I believe the big upper line goes to the cannister. Thats all thats left and I have yet to see this in any diagram. Not even sure what the assy is called. I completely missed the vent line to cannister as I was blinded by anger and fatigue messing with this thing.

 

The part number is 04809305ac and says its a vapor liquid separator. It also acts like it may be valved inside. Of course..... discontinued.

"This product fits 40 vehicle variants.
Chrysler: 2 models, 21 variants between 2001 and 2002.
Dodge: 2 models, 19 variants between 2001 and 2002."

 

That’s part of the refueling vapor recovery, meant to minimize vapors escaping to atmosphere during fill up - it’s a secondary part of the EVAP system. The diagram shows it ties into the EVAP via the canister. It’s purpose is to prevent liquid fuel from entering the canister.

I’m still working through the system operation to narrow down where the restriction could be (small children = limited time on weekends), but from what I’m seeing between the two diagrams, the only inlets for fresh air are the filler cap and air filter for the LDP.

We know the filler cap is good, and we know the hose for the fresh air filter isn’t kinked like in the bulletin, but what about the filter itself? Are you able to open it up and inspect/clean it? If not, try running the system with the air filter off (one test drive won’t hurt anything) and see what happens.

 

When I applied air to the line at the purge valve, air was coming from the filter assy.

 

Found that the valve between the charcoal cannister and ldp pump has a busted diaphram leaking engine vacuum into the system at the valve.

 

So that fixed it or you’re still hunting for a replacement?

 

I am awaiting the replacement to arrive. Ill install it and again start testing the van to see what it does.

 

Replaced this valve and vacuum leak is gone. However the issue persists. However this time when I pulled off the U hose between the valve and the charcoal cannister exit port there was a definate vacuum lock that released. The hose after that valve goes to the LDP. I then went forward of the LDP valve and unhooked the hose to the filter. Drove the van and the same issue with the needle plummeting. So, all that is left is the LDP itself. It has vacuum going to it split off with a Y. The other from the Y is a line going to the valve I replaced. The main line comes from the purge valve. All is good till the valve opens while driving then poof bye bye needle. I can come back and sit in the driveway and almost tell immediately when the purge valve closes or make it close by shutting off the van then crank it back up. The needle recovers and DTE starts back up. Also, the second pic is what I found when I opened the valve casing. When this valce is at rest, all three ports are upen. When fed vacuum at the small port, the bottom large port is closed off.

Replacing the LDP is not cheap. I can only wonder if a valve in it is stuck open allowing vacuum from the engine to also pull the entire system down. Otherwise it is working correctly and this issue cant be fixed due to a programming failure in the ecm. I am coming to the end of the road here.