Hey everone, I have a 1989 iroc 5.0 TPI and I've been have this issue since I had the fuel pump replaced about 3 years ago. It wasn't bad 3 years ago when the fuel pump was replaced but now it is significantly worse. I tried 3 seperate gascaps and none of them make a difference. I'd say I get around 8-9mpg now and the car idles rough around 5-600 RPM, sometimes it'll Idle around 1000 and drop back down. There is a strong smell of gas from the rear of the vehicle considering everytime I drive it some gas will pool up in the gas cap door. I honestly do not know much about the fuel or evap systems so I have no idea where to begin. Any advice or help would be really appreciated, thank you!

 

Do you have a charcoal canister installed under the hood? Did you check to see if the vent valve is working properly? It's attached to the axle and looks like a flying saucer. Its a 2 way valve, if too much pressure is in the tank, it will vent. Something like 6 psi.

 

 

Thanks for the reply! I have a canister under the hood, I'll take the vent valve out after work to see if its working. If there is an issue with it it should just need to be cleaned? I read that people were having issues looking for replacement ones.

 

See if all the lines are hooked up. You may need a mirror under there to see. Good luck!

 

The vent valve aka UFO isn't likely to be the problem... the most likely thing to happen when that goes bad is, the tank gets a vacuum in it when you drive the car for a long time, from air not being able to get in and replace the fuel the engine has taken out.

More likely your issue is related to the canister. Its lines can of course get plugged up, and it itself can as well, from mud and whatever all else. There's a writeup on here somewhere that somebody did where they took all its old guts out, cut a piece of some kind of mesh (might have been fiberglass cloth reinforced with window screen, at least that's something that would make sense) to make a "bottom", and replaced the charcoal with the stuff you can get at a tropical fish store.

 

I went to take it off to check it but the clamp is rusted four ways to sunday so I threw a little PB on it and ill try to get it off tomorrow, Ill take a look at the canister too, Ill look around to try to find the rebuild on the fourms, thank you!

 

So the vent valve is fine, had some nice weather over the weekend which was nice. The valve was surprisingly held to the clip by two zip ties and the plastice at the top was cracked, but it still worked so that was nice. Tonight I'll check the vaccum hoses. With the canister though, how will I know if it's bad? Are there any tell tale signs?

 

I think the issue might be with the lip of the fill neck.

 

Yeah sometimes it's the obvious things...

 

Any Idea on to how to go about fixing that without replacing the neck? Was thinking about seeing if I can get underneath it with a small punch to try to get it out. I also know that JB sells gas tank repair kits, maybe using the epoxy from that to fill the dent.

 

Replace the tank and be done with it