About three weeks ago, I replaced the two vapor valves (and rubber grommets) located on the top of the gas tank. I had been smelling gas, and sure enough, one of the grommets was badly deteriorated. I decided to replace both valves while I had the tank down. This seemed to solve the problem, but after a few days, a gas smell returned, although much less noticeable. I also started having a problem with the gas tank getting pressurized. And then a CEL -- if I remember, it was "catalyst deficiency" or something along those lines.

I decided to drop the tank to make sure I didn't crimp one of the hoses leading to the vapor valves. They were not crimped, however, when I blow into the hose (the other end of which I removed from the t-fitting on the hose that goes to the charcoal canister), air flow is very restrictive. I think air is moving through the hose, the valve, and into the tank, but just barely.

Does anyone know if this is correct for these valves? Or might the valves be defective? (Kind of hard to believe; they're both new. Maybe one, but both?) Any help at all would be appreciated. Thanks.

 

Oh. I just discovered that fumes flow OUT of the tank, through the valves and hose to the canister, not from the canister to the tank. So maybe the valves are defective, and not allowing fumes to escape the gas tank?

The manual I have says, "When the pressure in the fuel tank exceeds 3 psi, a pressure relief/rollover valve opens, preventing excessive pressure build-up in the tank..." Where is that valve?

On another note, isn't the gas cap supposed to have a pressure relief valve built in that releases pressure if it gets too high in the gas tank?

 

Well...I disconnected the end of the hose that fits onto the intake nipple of the charcoal canister and then blew into it. I couldn't. It's blocked somewhere. I tried blowing into the other end, at the rear. Same thing. Which makes sense. So it's blocked somewhere in that line. Most of which is a metal tube, with rubber at the ends.

Do you think I could get the same diameter metal tubing from an auto parts store and carefully bend it where needed to replace the existing metal tubing?

 

Never mind...all fixed. Cleared the blockage in the tubing and put it all back together. A drive tomorrow will let me know if I fixed the problem.

 

Glad you worked it out, and thanks for posting this. I found it educational. I've never had occasion to look into this end of things, so this was all new to me.