I've done some searching and I have about convinced myself that I have clogged fuel vent line or charcoal canister. Here are the symptoms I have noticed.

1) significant pressure when I take the fuel cap off
2) fuel odor, particularly at rear of car but no obvious leak
3) I have noticed a whistle, like a presure leak coming from the gas tank area. Seems to happen mostly when the tank is near empty
4) It has become hard to start in the morning.
5) I sometimes noticed a gurgling noise coming from the gas tank.

What does the collective wisdom think?

 

I have the similiar pressure but I have the vent line capped in the engine compartment. So I attributed it to that. Fuel odor as well. I've thought about putting an FB charcoal canister on and venting it to the air cleaner.

Are you using your choke to start the car, its cooler now.

The whistle and the gurgling I've never noticed. Is your car haunted?

 

I have that in my '83. Pretty sure the vent is just clogged. It's a really tiny little line. I will fix it by removing the charcoal canister and slicing off the vent line near the tank, venting it to atmosphere. Just haven't gotten around to it yet. I'll let you know the results when I do.

 

Car may be haunted... but I don't think this is a spiritual issue.

I am going to pull the vent line off the canister before I go home tonight and see if anything changes.

I'll let you know.

Tim, did you see Stu started a thread for a spring time Saturday meet.

 

I have the same problem that I have been saying I will fix.

 

Both RX-7's that i have owned gives off a psshhh pressure noise when the gas cap is removed, that is normal.

 

I don't think it's entirely normal. I plan to retain the charcoal canister in the engine bay and instead of the dinky little stock breather line, I'm going to use the stock 1/4" return line.

 

The back pressure in the tank when you take the gas cap off isn't normal?
I always thought that it was normal....

 

It's not pressure. It's vacuum being pulled on the tank because it can't vent. Most of us guys who have went with after market intakes and carbs solve this problem by venting the gas cap. You can either try to find a vented cap, fix your clogged vent line, or just drill a small hole in the center of the cap. If you are running a higher pressure, higher volume fuel pump, you would have vacuum locked the fuel system a long time ago. There is a vent check valve in the top of the tank. This could be stuck also.

 

So let me get this straight, when I take my gas cap of I should not get a huge PSSSSSS coming from the tank, Cause mine is full of pressure, it almost falls rite out when I turn it loose.......
Thanks CRUZ

 

My GSL-SE does that. Anytime I remove my gas cap I'll get a hissing noise. It's because the gas tank builds up pressure. You could try getting a vented gas cap but I'm not sure if you need the pressure in the tank.

Mine's always done that and I've had no problems with my car. But, then again, maybe it's because I have EFI.

 

I had this problem and it actually created such a large vacuum suction that the tank vacuum locked and the car died. to get a quick fix i drilled a hole in the cap, still plan on doing a permanent fix but have not got around to it

 

When I had my OER, I never had any problems. No CC, capped the return line to the tank, never heard the PSSSSSH noise when I took the cap off, and never smelled gas.

 

I did that, only i relocated the charcoal canister to a location near the tank under the car, thus keeping the engine bay less cluttered.

 

Well here are the early results. I simply unplugged the gas tank vent line from the canister yesterday.

* So far no whislte coming form the gas tank area. I would typically hear this when I got under a 1/4 tank. I ran the gas tank down to near the bottom of the E mark. No noise
* The canister inlet for the gas tank vent line is complete clogged. It looks like there originally was a needle size opening in it. I'll look into this some more
* The vent line from the gas tank seems to be open. I blew through the tube for as long as I could and never sensed any back pressure.
* I had to fill up this morning. No phssssssst sound.

I am going to montior this over the weekend, and try to unclog to the canister inlet. I'll let you know what I find.

 

You could probably pop the cap off the canister and soak the cap in gasoline, it "should" unclog the pin hole

 

No, a tank should never hiss. thats why tank vents where created. tanks imploded and rapidly escaping fuel vapor ignited or gave nasty chemical burns to folks in the 20's and 30's.

BTW, I noticed the same problem today with my car. thats why I'm posting to an old thread. I'd hate to get the business for re-posting a similar topic.

Just proves searching works and keeps the search police off your back.

 

Well shoot, if Mike will post back up and tell us what he learned about his charcoal canister, we'd all be a little smarter. Where'd you go, Mike?

 

Sorry, I'm back. I got hung up servicing local moms. Yes I learned - Vent goood! Dirt in vent BAAAD! Thank you. NOw back to your mom