Canister leak...

85_Daphne

They call me Cowyboy...
Joined
Jan 27, 2007
Have an 85 with 66k miles, stock other than a conversion over to e85. Driven the car the first time in a few weeks yesterday and today and after the drive I noticed a puddle under my driver side front fender. Smelled the liquid sure enough it's fuel. Look under the hood, and under the canister is wet. Went and unscrewed the gas cap and heard pressure release. The first time the puddle happened I was on E this time I had a full tank. Any ideas on what would be causing my issues? Didn't happen after I filled up yesterday and drove home. So I'm stumped. Any advice is helpful. Thank you.

-Cowboy
 
Pressure or vacuum? I don't have any experience w/the 84/85's, so I'm assuming the cap may be vented and may have become blocked. Creating a vacuum. I'm just throwing some thoughts out there, so don't take anything as gospel. Any stuck check valves or maybe the filter in the canister just needs changing?
 
If the 85 is similar to the 86/87 fuel system, there should never be pressure or a vacuum in the tank. As fuel is consumed the gas cap vent allows air into the tank. As the tank heats up from a running engine the CCP system relieves the pressure.

I've seen the fuel filled canisters on third gen Camaro's and Firebird's. It is usually caused by reversing the vent and return lines at the tank after a fuel pump change (easy to do, both are the same size).

On the pump hanger/sending-unit, the vent line is at the top with a roll-over check ball/valve.

While the return line is near the bottom of the tank. When reversed, as the fuel heats up and expands it is pushed out the return line into the canister.

RemoveBeforeFlight
 
I did a fuel pump change two years ago. Why would I be acting up now? So perplexed
 
I did a fuel pump change two years ago. Why would I be acting up now? So perplexed

Not sure, do the '84/'85 cars use three different diameter lines at the tank? The '86/'87s do which makes it tough to switch up the hoses.

Although, something just came to mind that I read here. Someone else had this issue and found that the hose between the fuel pump and hanger was spraying fuel upward, right at the vent. Needless to say he too had fuel running out of the canister.

Don't recall if the hose clamp was loose or if the hose had a split. It may be time to drop the tank and check things out.

RemoveBeforeFlight
 
First and foremost thank you for helping me and chiming in, I appreciate it. Secondly, here's an update. I put on a new push button vented gas cap as well as a fresh canister filter last night and drive to work today 20 min drive and got the car up to temp 175-180 and didn't have any issues. So maybe all I needed was a new cap and filter but I'll keep a close eye on it and see if it happens anymore. It's just strange that it's happening so sporadically.
 
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