I am wondering if anyone has had a problem with a fuel smell. If I fill up my car and then put it in the garage, the next morning the smell of gas is so strong it almost knocks me down! My mechanic has checked all the fuel lines, I got a new cap, and my injectors aren't leaking either. Has anyone had this problem before? I'm thinking maybe I should crawl under it and check it out for myself. There must be a cracked hose somewhere...He said there isn't though.

 

I had this problem when my injectors were leaking. Once I fixed that the problem mostly went away. It will still smell like gas at times. I don't know if it should be that potent, but some fuel smell from these cars is not uncommon. Did that car come with a charcoal canister? I know that if the filter gets really old and clogged it won't vent as well and you can get alot more fuel smell.

 

Like duo said, check out the charcoal canister and the vent and vacuum lines to/from it. It could be the injectors, but the fact that you say it's only right after you fill it up and put it in the garage makes me think it's one of the vent lines has cracked (I think the '76 had a metal vapor canister, not the old plastic one). It could be the fuel filler neck, as well, but your mechanic probably would have seen that (hopefully).

It would be much harder for him to have checked the vent lines. At the vapor can end, you need to remove a couple of interior panels, At the tank end, a couple of them aren't really visible without removing the tank. It's not a hard job if you decide to check it out. Just a pain to dispose of the gas if you drain the tank. Usually there's a neighbor with a daily driver who will gladly take a few gallons out of your way. Just do it outside (garage door open) and all you need is a few wrenches, a clean drain pan and a gas can, maybe a funnel. Gas fumes will collect at the floor in closed spaces, so don't do it in a closed up garage or near a utility room with pilot lights. It doesn't have to be a gaping hole, either. A little hole/crack/leak could yield a strong smell of gas.
good luck,
Dave

 

Thanks for the tips, these are great ones and I think it is one of these things. I called my mechanic and asked him if he had checked the
charcoal canister and those vent lines you were talking about and he
hasn't! I can't believe he hadn't done it, but anyhow, I'm going to do it myself once the weather cools down a bit. He said he wanted to use a smoke
tool of some sort, not quite sure what it is, but it's been like this too long, so I'm going to do it myself once the weather cools down a bit. Thanks again!

 

with the smoke tool he'll pump smoke into the system and where the smoke comes out from is where your leak is. It's the quick way for a shop to find a leak. The faster they do things the more money they can make

 

Well, maybe I will give him another chance at fixing it then.
I have to say I absolutely love your car! And Cartmen is my favorite!
Are those lights on top real? :-)

 

I forgot to ask, if I decide on doing this myself, which interior pannels would I need to remove?

 

HAHA...that's not my car. There was a clown on here not too long ago and thats one of the photochops of him. Admin made it my sig and I just kept it

 

The vapor collection can/tank is in the right rear quarter, just above the fuel filler. So you need to remove the interior panel that's behind the right-rear shock/seatbelt tower. Notice that it doesn't look the same as the one on the left side of your interior. The extra bulge in the right panel is the vapor collection tank.

You might want to check out www.carfiche.com if this isn't translating into text very well. You can get a .pdf of the out-of-print service manual for your car. There's a nice diagram in there in the fuel system section that shows all the lines and hoses and tanks.

The bonus is you can see the fuel filler hose (another potential culprit) behind that panel, too. But to get that panel out, you might have to remove some of the ones around it, e.g. the taillight panel, that little piece of masonite decking to the right of the spare tire hatch, etc. You do have some wiggle and bend room with the panels; but, don't flex them too much as they are 70's plastic, so they can be brittle. Go for patience and persuasion more than force, and it'll come apart.

The smoke test should help tell you if the problem's up there (smoke coming out from behind the interior panel), or if it's at the tank (smoke up under the back of the car, or someplace else. It sure sounds like a vent line or filler tube, though, because you said you only notice it right after you fill it up and have it in the garage. I think it was drlew on here who had a filler tube go bad a couple of months ago. It was fine if he only filled the tank up about 2/3, but more than that and gas would start spilling on the ground from the fender area.

If it turns out you have to drop the gas tank to get at the fix, we can help with some directions on that, too (if you need them).

J - I didn't know the admins did that, I thought you had changed it yourself. Either way, too funny!

good luck!
Dave

 

This is a great help, I'm going to check it out myself next weekend. I bet it's just a little thing I can fix easy. And yes, it's only when it's a full tank, or nearly full. :-) I will keep you posted on how things go. I sure don't want gas spilling out of my car, the stuffs like liquid gold these days.

 

36 years ago someone installed the side bump trim on my car and drilled through the quarter panel into the over flow tank! You might want to pull the interior panel off and take it to the gas staion to see just where it's coming from.

 

Too funny! Along time ago I had to fix the rear window washer on a newly purchased used Subaru wagon (not mine). It would only hold about a half cup of washer fluid, and then somehow spill onto the ground. Turned out a body shop had fixed a minor fender dent by doing the drill-and-pull, but had drilled right into the washer tank, which Subaru had located in the left rear quarter panel. Easy fix with some resin, but very weird. I was always taught to check all the way behind what you're drilling, a good %50 farther than your drill bit would reach. Guess that doesn't make for rapid turnaround on insurance bodywork...
Dave

 

well my car SOOOOORTA does something similar with gas smell.. ok this is the thing. here i am driving my 71 240z running carbs... and when i get OFF the car. i relaize i dont smell like the cologne i put on when i got in the car but more like FUMES like GAS sorta.... its annoying i dont wanna get a gir in my car knowing she' end up smelling like GAS.. NOT KOOL . so idk what the hell is wrong with hit

 

Wow, yeah, "Here, hon, let's go for a ride! Don't mind the service station smell, just keep the windows down.". That wouldn't go over too well.

While the vapor tanks/lines are nearly identical year-to-year (and you should check those, maybe the charcoal can lines are dried out and cracked?), the carb set-up has a lot of different ways the fumes might be created, but I only really know the EFI system. theramz, you run carbs, don't you? Any ideas?
Dave

 

The 70-71s are notorious for exhaust fumes coming in the rear of the car. Also the fuel tank over fill hoses run inside behind the rear plastic panels. Seems like a lot of work but you need to take everthing out and check for holes and missing body plugs, ther's one under the antennae right over the muffler. If your Z is early 71 you might have the louver vents in the deck lid. Seal them off from the inside. I spent many hours trying to solve the problem. Even now at high speeds with the window down it sucks fumes in. The design of the car produces a back draft at the rear sucking in fumes. I extended my exhaust tip out another 4 inches and that helped too. Check your rear hatch molding, it should be replaced. Having the dash and floor vents open helps push the fumes out.
If it's gas you smell then you have to check for leaks most likely in the rear area. The 70-72s don't have a cannister. If the carb bowls over fill then they simply puke the gas into the air cleaner via a vacuum line in the top. I'm thinking about wrapping the inside of the car with sound deadening material to cover all the other possible holes. This should keep you busy for a while. Tom

 

That was the next thing I was going to ask about! If I'm going high speeds, then slow down, the exhaust fumes come rite in the car when I slow down! I have replaced the seals around the hatch, and also extended my exhaust tip! Maybe after I find and fix the fuel leak, it will get better. I've come to the conclution I just have a stinky little car!

What part of the inside of the car are you going to wrap with sound deadening material?

 

There is a vacuum control valve on the manifold balance tube. It is called an anti-backfire valve. When you back off on the throttle it opens the carbs slightly so you are'nt dumping in an ultra rich mixture. You can test it with a vacuum pump and adjust it per the manual. To see if it is working run the engine at 3k rpm and back off sharply. You should see it pull the throttle open slightly.
As for the sound material I think I will literally wallpaper the inside of the car from the seats back. I think Eastwood sells it.

 

My 280 is fuel injected so that won't work for me. I'm not so sure about wallpapering my car either! Have you seen that on a z before?

 

What I meant is removing all the interior panels and glueing the sound proofing material sheets to the metal inside the car to seal off any leaks. it will have to be cut and pieced in place. The inside of the quarter panels and the bottom of the hatch area floor and spare tire well, even around the tailights. Maybe shoot some insulation foam in the corners and seams.
i ThiNk i aLreAdy haVe braiN damneGe.

 

It's from all those fumes you've been breathing! ha ha ha

 

naah but really that sucks... i mean i have a SICK *** red 71 240z and people JOCK my ride like they stare.. not just cuz of the driver haha j/k but nah.. idk i have'nt given my girl a ride on it from fear of that... i dont want her going in smeling like flowers and coming out smelling like we just made a pit stop at the gas station and took a shower with gas :P ... but hmm yeah i have the same problem i go on the highway and i go pretty fast..... and as soon as i let of the gas pedal it smells and i dotn get how if the exaust goes BACK! out BEHIND the car.. how the hell does the fumes come inside the windows or whatever and end up making me smell you know. hmmmm tricky. but o well yeah i had a problem with that before but i cleaned the carbs when i noticed my car bogging out i turned it off and there was fuel leaking out of my intake filter thin i was like WTF... that's not supposed to leak and i took it off and a a small little river of gas was being squirted when i turned the car back on from apparently the floater must've been stuck with some gum or somehting. but yeah.... that smells a killer i dont have the EARLY 71 i dont have the 240z emblems or the small air vents... i wanted one of those but o well. yeah So something that's not relativly HARD that i can do to make SOME of the smell minimize or go away?.... HELP! :P

 

Although you both have the same issue: smelly hydrocarbons getting into the interior, there are enough differences in the details that you probably have different root causes.

Z_lis has vapor from unburnt gasoline getting into her interior only when the tank was just filled, and it's parked in her garage. That's probably filler and/or vent lines. Liquid is high enough to leak out of one of the handful of connections to the tank, or the vapor pressure gets high enough in the now-smaller volume of air that it can push out through a vapor line leak at the vapor tank, or a blocked/bad line to the charcoal can.

Superduner, sounds like your symptoms are more when you're running the car, not the parked-in-the-garage buildup like Z_lis has. If it's an unburned gas smell, I'd try the stuff theramz mentioned (I didn't know the carbureted Z's didn't have a vapor tank, theramz, thanks for the info, very cool to know!). I just don't know much about the pre-EFI Z fuel system.

Exhaust or crankcase fumes, though, are another story. Cruising at highway speeds, if you're getting exhaust fumes coming in the car, there are two areas to check.

First is the backend. The shape of the Z, while mostly quite aerodynamic and of course beautiful, does generate some weird pressures and patterns of air flow. In particular, it does try to suck exhaust fumes into the passenger compartment if there's any opening whatsoever in the back. The main reason is the graceful sloping hatch, with the nice short vertical taillight panel, combine to make a fairly powerful eddy/vacuum. The why of this is easier to see than explain. Check out the "Nissan 350Z Concept Commercial" that this guy has posted: http://www.yadamnfool.com/Z_Commercials2.htm
The whole commercial is great (makes you want to call in sick and just drive your Z all day), but seconds 0:05 to 0:08 on the timer has a great shot of flow-testing the S30 body shape.

Note how the particles and flow pileup and push at the back of the car from the outside. There's even a nice swirling eddy there to help catch the exhaust fumes. If everything's sealed up and the exhaust is the right height and length, there's no problem. But if there's any gap, you can see how the fumes would go right in. The main gaps after 30 years can include rust holes/seams like theramz mentioned, the hatch surround weatherstrip, vent line grommets where they come into the body in the luggage area, and taillight gaskets.

With the exception of the rust holes, none of these are difficult or expensive to repair. A tube of really good black weatherstrip adhesive, some masking tape, a couple of basic tools, and whatever new gaskets/grommets/weatherstrip you want is all it takes. MSA just issued some remanufactured vent line grommets, so it's even easier now. I had to rebuid-my old ones with a bunch of weatherstrip adhesive this past spring; it worked fine, it was just tedious. If you have the really early Z hatch vents, you need to check those, too. They'll suck fumes in if they're not absolutely perfect. Probably part of the reason why they dropped them for the emblem venturi-type vents after a few years. The taillight gaskets are kind of silly for how much they cost and what you get, but they are very effective at sealing that back panel up tightly.

The second main way exhaust fumes get into your interior is through the firewall. Firewall is a silly name. It sounds like it should be impervious, but when I stripped my car down, it looked like swiss cheese with all the holes for the wiring and heater lines, and a/c, and steering, and brake, and clutch, and hood release, and on and on. I think if I ever had a fire in the engine compartment, I'd be a goner if I didn't get out of my Z immediately. Thing is, every one of those holes has it's own grommet and after 30 years all the fumes and nasty chemicals and stuff (plus just plain age) have probably about destroyed most of them. That gives more openings for fumes to get in.

Check out the airflow video again. There's no firewall in that test, but you can still see how there'd be another pressure area and eddy that would easily push fumes in at you. You can also see why you want an airdam to prevent all that air from getting under your car at highway speeds. The grommets in the firewall are easy to check out, and pretty easy to replace. A good indicator is your throttle boot. If it's all dried out and disintegrated, you need to get some new grommets/boots and a tube of silicon sealer. Mine was actually gone when I bought the car. Check every place where something goes through the firewall. My hood release and speedo cables were especially leaky spots.

One last thing: you mentioned that letting off the gas while driving could also produce fumes. It's worth checking your crankcase ventilation systems for leaks, bad or dirty valves (PCV valves are cheap and easy to replace), cracked hoses, leaky valve cover gasket, that sort of stuff. If you have an EGR system, it might be worth looking that over for leaks, too. Just a thought.

Hopefully this is helpful. You can at least triage a lot of these potential interior leaks with just a tube of silicon (like $2 at the hardware store). And that'll last a good while. The "right" way really is to get new weatherstrips/boots/grommets, but that is more work and money, so this way you at least have some choices.
good luck,
Dave

 

I had an exhaust leak that proved to be hard to find.... replaced all hoses, filler, everything including the weird metric vapor line and the one that is threaded through the frame... ALL OF THEM!!! I installed new inner and outer hatch gaskets.. purchased and installed new hose boots through floor, taililght gaskets, hatch plugs, etc, etc, etc... it still smelled like fumes in the cockpit...

It turns out that some bad bodywork had left a gap btween the rear quarter and the floor extension on the driver's side.... I sealed that up with some seam sealer and all was fixed...

The car still stinks up a garage... but that is because it has triple weber DCOE 152s installed... there is nothing to catch evaporating fuel vapors... I jsut store it in the garage not attached to the house.

 

Well, I let my mechanic try again with a smoke tool he borrowed. I didn't have much gas in the car when I left it for him in case he wanted to drop the tank. I got it home, filled it up the next day and sure enough it still stinks. He said he didn't drop the tank, but he checked the charcoal canister, vent and vacuum lines and the vent lines at the vapor can end. (I made sure to tell him these things) He said he had found a craked hose and thought that would be the end of it, but it's an old car and I bet there are many cracked hoses, I don't think he should have stoped at the one. Anyhow... he wants to try again with it having a full tank of gas. He is a great mechanic, but I've about had it with his attemps on this problem. I'm going to drop my own tank and take that pannel off in the back and see what's going on for myself. I am really good at working on the Datsun, I just have an office job and have kinda liked taking to the shop! keeps my hands looking nice! But screw that, I'm going in! I bet I can find it for myself better. I'm not sure if he's telling me the whole truth, I think he just hoped it was the one little hose. I am wondering... is there a gasket of some kind on top of the gas tank? Also I have the Nissan shop manual on the car, but it's for a 77... I think the 76 and 77 are pretty much identical don't you?

 

Whew... you can go figure that the lines are bad... there are many lines running between the vapor recovery tank and the fuel tank... It really is silly for anyonew to waste all that time trying to troubleshoot a 30+year old fuel system... the first thing to do is replace EVERY SINGLE LiNE... This means drop the tank... and start hunting them down...

There are 2 hard to replace lines... one that runs THROUGH the passenger side rear frame... and there is a large diameter hose that is an odd diameter... There is also a tendancy for several of the hoses to KINK when everything is bolted back up... but these issues are minor compared to the assinine trouble shooting that has been performed on a 30 year old set of rubber lines...

You would think that a mechanic would realize that the job would involve a complete hose replacement from the start... I can only imagine that this guy is younger than the car he is trying to work on.. to him a 1999 car is old.. LOL!!! and tell him I said so...