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Charcoal Canister disconnected... Is this a problem?

Hi all,

I've recently purchased a '93 F-150 5.0L and I noticed that the charcoal canister is disconnected. The larger diameter hose going to the solenoid is plugged, the smaller diameter hose going back to the tanks is wide open. My question is: is this a problem? At the very least it seems a bit questionable to have the tanks venting to atmosphere under the hood. I have no idea when or why it was disconnected. I don't have a check engine light so I don't think the solenoid is malfunctioning. Any thoughts?
 

Fellro

Moderator
Staff member
It is pretty much just vapor recovery. It is more EPA than engine function. The danger is if the tank gets too full it could possibly vent true liquid. There may have been a leak upstream or such to the tank that led them to block it off. You could try hooking it up and see if things trip a code.
 
That was my first thought: if one of the fuel pump check valves leaks and a tank overfills, will I bring straight gasoline back through there? If I did, it would probably be better in the intake than the engine bay I suppose...
 

Fellro

Moderator
Staff member
It could be a possibility. Hadn't really thought about that particular possibility.
 
Following up for posterity: I recently came out of the county permitting office only to see the Ford hemorrhaging fluid on the ground from the engine compartment. Popped the hood and found fuel dumping out of the tank vent line! I was heading out of town so I left it with the mechanics who found a tank vent valve stuck open. They replaced both vent valves and hooked the evap canister back up. No trouble there since 👍🏻

But now the front tank overfills at the gas cap when I run on the rear tank. I'm pretty sure the check valve on the rear pump is good because the rear tank was bone dry when I bought it, so I'll just nurse it by driving down the front tank first until I can do fuel pumps....
 

Fellro

Moderator
Staff member
Seem to recall that there is a check valve in the fuel line but could be wrong on that. Either way, it is definitely a case of the check valve for the front tank allowing it to go into the return side despite being the rear tank in operation.
 

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