So my charcoal canister doesn't quite pass the tests in the FSM and a new one is hard to find, so I saw a writeup on how to clean the check valves and may give that a whirl.
But for the time being, I just removed it and plugged the purge line going to the BSV/TB, but out of curiosity I decided to suck on the tank vent that goes into the canister. I was expecting completely free flow with the gas cap off, but I'm getting serious restriction. It will eventually give me some gas vapor in the mouth, but takes considerable suction (stop your jokes right now).
Am I wrong to assume that it should flow freely with the gas cap off? I see nothing in the FSM to indicate any other check valve in that particular line. I traced it as far as I could to the tank and I don't see any obvious kinks. I wouldn't expect a gas vapor line to have any obstructions in it, but is that possible? Really don't want to pull the tank just to check it, so curious what you experts know of that system.

 

Bump.
Anyone willing to give a toke on their vent hose that goes into the charcoal canister and tell me if there is any resistance?

 

What do yo mean it doesn't pass the tests in the FSM?
I've had my 93 3VZ for almost 15 years, I don't know what you're trying to say.

 

In the EVAP section of the FSM (pages EG1-86, 87) there are some inspection tests for the charcoal canister. In particular, it says that if you blow low pressure air into the "tank pipe" of the canister (where the fuel tank vent line connects) that air should flow with no resistance out the purge and drain ports. Air does move through mine but not without a good bit of resistance.

My question was about the vent line coming off the fuel tank. Mine seems to be plugged in addition to the charcoal canister being plugged. If I disconnect the vent line from the charcoal canister and try to suck air from the fuel tank (also with the gas cap removed to allow air in from there), it will not move at all. Or if it is moving there is extreme resistance. I checked diagrams and don't see any check valves in that setup except at the charcoal canister, but wanted to confirm with someone else that air should move freely in that line. I would expect that if you took the vent line off the top of the charcoal canister (it is the larger of the two hoses) and just tried to suck air through it, you would get fuel vapor with no resistance.

I have had my truck for 18 years and never really cared what that canister was on the passenger firewall, but now that I'm troubleshooting some misfires on a new engine I'm learning a few things!