OK. That can mean that moisture (car wash, rain, etc) over 300,000 miles has probably made it's way into the canister. Trust me, that activated charcoal in the canister is ruined and is not properly storing the vapors. You might have other issues, and I have started to write up some test procedures for the system overall, but haven't finished it yet.

EDIT: I believe there is less than two pounds of charcoal in the canister. So if you count the wight of the canister itself, it shouldn't weigh more than 3 pounds (roughly). A contact of mine out in Texas told me once that he sees a lot of Vapor Canister problems, especially from people that drive on dirt roads (not that it's the case for you). He'll weigh an old one compared to a new one and it is always quite a bit more heavy.

 

Makes sense. Looks like a new canister is in my future. I edited the previous post with some more info that might be useful

 

Here is the diagram I've been preparing for the leak tests. The instructions are pretty long an not finished yet. Did you get a MityVac?

 

That looks 100% correct from what I've seen. I haven't gotten a mighty vac, but if O'Reilly or autozone rents them, I can have one quickly.

Do any of the test procedures involve a bi directional scan tool? I don't have the ability to command the solenoids to open or close

 

Referring to post #30....yes, the fuel trim is off the chart. The LTFT is the base. Whatever it is at the STFT will use as 0. So in reality your fuel trim is around 45%.

As things get better your STFT will go into the negative, after a certain period of time the STFT will drag the LTFT behind it and that sets a new base. Just remember the STFT always sees the LTFT as 0, no matter where it's at. So you have to add the STFT & LTFT to see what the actual FT is.

 

No, I'm drafting the instructions so all you need is a MityVac, some vacuum line caps, and little bit of vacuum hose.

 

Just to be clear, the code you got may not be related to the EVAP issue. But we know you have an EVAP issue that needs to get fixed either way. Could you post the freeze frame data from that code?

 

P0305

Fuel sys 1: CL
Calc load : 47.8%
ECT °F: 178
STFT B1%: 19.5
LTFT B1%: 25.0
MAP (inHG) : 25.1
Eng RPM: 2511
Veh Speed (mph) : 51

That's all the freeze frame data

 

The fact your RPM was so high makes me think the code is not related to EVAP. It would be nice to know the TPS angle. But more than likely the throttle plate was open quite a bit. Which would mean even if the EVAP was sucking pure air it probably wouldn't matter. Unless the VCM calculates an expectation for vapor, but I really doubt that. This problem is not likely to be your "glass half full" problem .

I would definitely go ahead and change out that EVAP canister. If your truck uses the same one as mine, you can get an AC Delco off of rockauto.com for about $80. It was cheaper than the store brands at the auto parts stores.

 

Don't know why the freeze frame didn't show throttle angle, live data does. But if I had to guess, I would say the throttle wasn't open very much at all. If I open it more than a crack, the truck falls on its face, and I'm afraid I'll get rear ended.

The way to make it move the fastest is to manually shift gears, and keep it at high RPM, and low throttle opening.

I'm definitely gonna get it from rock auto. Locally it's $243, rock auto an ac declo one is $91