Gasoline odor

I need some ideas - and I also asked this on the other forum I follow. Unfortunately the ideas didn't pan out so I need some other fine minds thinking about this.

My '31 has a rear mounted gas tank - a Tanks, Inc '32 tank. It has their standard roll over valve which is also the tank vent as well as an unvented fill cap. The fumes coming out of the vent hose are b-a-a-a-d and to the point that there is even some liquid. Overnight with the garage doors closed it's unbearable until it airs out. One suggestion was to use an early '70's Chevy p/u vapor canister. Not a bad idea but they are fairly expensive (new ~$90) and in my area junk yards have processed vehicles that are that old into scrap to be shipped to Japan and made into econoboxes or they are blobs of rust in a field. Also it would require a couple of lines - a vacuum line to operate the canister and a line to the PCV or vacuum connection in the intake manifold - in other words, a sloppy mess of hoses. Do I need to vent the cap? I wouldn't think so. But....

I'm in the process of trying something I made up using an activated charcoal filter (a Brita water filter). So far, the results haven't been successful, but I forgot to water soak the filter to activate it to work. It's been soaked and on the vent now, but my guess - it ain't gonna do it!!

With that said, others must have had excessive gas fumes from their gas tank vents and on street rods. How were those fumes handled? Why this car when others didn't have that problem? And before you ask, there is only about a half tank of gas.

HELP

i think your roll over valve maybe to close to the tank if pushing fuel out the tank .could loose the roll over valve and make up a loop ?

Strange that you never mentioned or noticed the fumes before.!.! Was this the same tank in the car all this time? I used a tanks system, tank & roll over valve and have never noticed fumes around the car! Are you running a return line back to the tank?

OK guys, this is the vent/roll over valve that's in the tank top itself:

http://i70.photobucket.com/albums/i8.../Ventvalve.jpg

It's one of the two types that Tanks, Inc supply based on what vehicle the tank is for - the other is one that fits in a fill door or in a fender well and at the end of the vent line. There has always been a little bit of gas odor, but since I put more then a gallon or two in the tank(probably has 6-8 gallons now (14 gallon capacity), it's gotten much worse. Pat, I actually added about a 5' length of tubing, ran it through the frame to the back side of the rear fender and coiled it up behind a fender brace - no help. The next morning, same thing.

Mike, with a Performer carb and Carter mechanical 5-6# output fuel pump, I don't need a return line

This is an early version of the tank plumbing before I went to a 3/8" hard SS gas line. The vent/roll over valve is the brass fitting in the middle. The tubing comes from that valve to a point about an inch or so below the bottom of the tank:

http://i70.photobucket.com/albums/i8...intedpt2-1.jpg

Dave,
Evolvo was just a bit ahead of me hitting "submit", and I went back to look at your post again so I'll state that I agree with his analysis. The picture of the tank helps, as I was having a hard time envisioning your layout based on my trunk mounted Tanks, Inc tank. Your vent/rollover valve ball rolls freely in the tube, I assume? With that step down in the front of your tank the bleedback hole on the rollover valve tube could be submerged if you top off your tank, couldn't it? Doesn't explain liquid coming out with only 1/2 tank, but I think the answer is to run your overflow tube up from that fitting as far as you can before looping it back down as Evolvo said. Not sure that you couldn't just terminate it up high, like at floor level above your differential, but a little down turn is probably best.

looks like its in the lower part of the tank wrong place should be at the higher point on the tank or up higher the tank . i think it is siphoning try a riser on it or plug it and just run a vented cap or vent the filler neck

Evolvo What you are saying about that little pumping action is exactly what I believe is happening with the non vented gas cap. Yes, I could vent the cap by drilling a small hole, but then I run into two problems - possible slosh on my new $$ paint and a second fume exit.

Now, the hard part - room for much modification above the tank - not much. I have a standard 'A' trunk with a high sill that might allow a few inches for a loop, but probably not to the height of the tires. And since I actually have an access hatch for the sending unit and have to open it to fix the ground will give it a shot. If it works, then I'll do a more permanent mod, but with that expansion and contraction of the vapors, am not convinced. YET

Whatever the fume outcome - I am still enjoying driving the car:D

I like Pat's approach. If you have room immediately above you could make up a pipe riser to get the bottom of that valve at or above the top of the tank. Still does everything it is supposed to do.

Good idea, Pat!!

Pat and Roger, you snuck in there while I was doing my two finger typing.

I'll not only try the vent line higher, I'll add a riser of sorts. I do want to keep that valve in there. Off to Home Depot in the morning as I need more tubing and some fittings. A pipe nipple and a couple of bushings and I'll take that valve right out of the tank. If I don't get ahead of myself, photos to follow

(It's a b@#$h to get in there)

Easy fix. Like others have already stated you need to build some elevation into the vent hose to prevent the fumes. Think of the way a sink trap works (in reverse) with standing water in the J-Tube to prevent the sewer gas smell from backing up into your house.

Just connect the vent hose to a piece of 5/16" steel flared tubing. Run the tubing up through the trunk floor or behind the rear seat. Run it all the way up to the highest point and bend a 180 (u-turn) in it, and then back down through the floor again. I then took a 1/8" NPT Ford type carb fuel filter and screwed it into the boxed frame and a short piece of hose connecting it to the new vent tube. The gas tank is vented to atmosphere through the frame "outside of the body" but running the tube through the body allows the height needed to prevent the fumes. Just make sure you size the vent tubing based on your estimated fuel consumption. It works!

2 finger typing :3dSMILE: i'm impressed, i'm still using 1 :(

I've had a similair problem and solved it by takeing the breather pipe up to just below the height of the tulip panel and then back down again through the floor.

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Originally Posted by IC2

Pat and Roger, you snuck in there while I was doing my two finger typing.

I'll not only try the vent line higher, I'll add a riser of sorts. I do want to keep that valve in there. Off to Home Depot in the morning as I need more tubing and some fittings. A pipe nipple and a couple of bushings and I'll take that valve right out of the tank. If I don't get ahead of myself, photos to follow

(It's a b@#$h to get in there)

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I'm off to get some plumbing supplies and give some version of all that's been suggested a try. I just wish this had reared its ugly smelly head before the upholstery was done as some parts really aren't going to be easy:CRY::CRY:
To get a high point on one side, I need to pull the battery, the other, the trunk lift - which will be the easier of the two. But I knew when I built this car there was going to be some 'interesting' days, so no big deal:D

I'll report back so at least there will be some record that others can use

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Originally Posted by IC2

OK guys, this is the vent/roll over valve that's in the tank top itself:

http://i70.photobucket.com/albums/i8.../Ventvalve.jpg

Mike, with a Performer carb and Carter mechanical 5-6# output fuel pump, I don't need a return line

http://i70.photobucket.com/albums/i8...intedpt2-1.jpg

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Wasn't thinking you needed a return, just couldn't remember your setup! Since I have the same tank arrangement as you I'm curious how you correct it as I may need to repeat it on mine!;)

What I have done so far is to take the vent out of the tank. Evidently it can become immersed in gasoline - and was actually wet on the bottom half inch. There isn't that much gas in the tank - possibly a half tank.

I made up a well using common galvanized pipe as shown and in this order from the tank:

- 1/4" close nipple
- 1/4 to 1/2 coupling
- 1/2 x 6" nipple
- 1/4 to 1/2 coupling
- vent valve

I attached about 10 feet of 1/4" vacuum line, ran a loop to about an inch below the tank bottom, back up to about the tank middle then through an opening between the frame and body. I then ran a -6-8" diameter loop behind the fender brace.

As of 4:17, (5 minutes ago), no odor from the hose and it's 89*, plenty hot enough to expand the fuel to give off gas.

I really can't take a photo where that set up is - heck I could hardly see the arrangement.

Dave, I don't think you want that first part of your loop because if you will tend to condense vapors over time and they will settle in that low spot. I believe your hose should slope up from the vent connection to your high point, then perhaps turn down. I still don't see any value in having it drop down to tank level, but I don't think you want any low points in that line.

I think I will add a riser like yours to my trunk mounted tank, just for grins. My vent line will run up to the top of the trunk, only about 6", then drop down to a drain fitting through the floor.

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Originally Posted by rspears

Dave, I don't think you want that first part of your loop because if you will tend to condense vapors over time and they will settle in that low spot. I believe your hose should slope up from the vent connection to your high point, then perhaps turn down. I still don't see any value in having it drop down to tank level, but I don't think you want any low points in that line.

I think I will add a riser like yours to my trunk mounted tank, just for grins. My vent line will run up to the top of the trunk, only about 6", then drop down to a drain fitting through the floor.

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Roger, at this point it's trial and error with the hose held only by cable ties. What I did is put a basic liquid trap in the line. If it doesn't work, then I'll see what else can be done including your suggestion. Unfortunately I'm trying to work with a fully upholstered car, including the trunk and really don't want to pull it out unless that's the last resort:HMMM::CRY::CRY:

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Originally Posted by IC2

Roger, at this point it's trial and error with the hose held only by cable ties. What I did is put a basic liquid trap in the line. If it doesn't work, then I'll see what else can be done including your suggestion. Unfortunately I'm trying to work with a fully upholstered car, including the trunk and really don't want to pull it out unless that's the last resort:HMMM::CRY::CRY:

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Dave,
I understand the pain of working with a newly finished car, and I would consider this to be a winter project, if needed. My concern is that a liquid trap is going to work. You will condense in that line over time, and then once you have a seal the tank pressure has to overcome that seal to vent. At some point you are going to get enough condensation that on a nice, hot day you fill the tank, park in the sun and as the tank expands you will finally overcome the head pressure on the liquid seal and burp fuel out your vent line. I think a vent needs to slope up from source to the peak. A "J" at the top keeps water from entering if you are planning to ford creeks, but other than that I believe it can terminate at the apex. Any condensation of vapors will then run back to the tank.

I guess that the next step will have to wait until Sunday/Monday - I got up at 0 dark 30 this morning and have driven to the furthest corner of Virginia from home, 677 miles. When I left home, no trace of odor, but......more to come, I'm sure:HMMM:.

Quote:

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Originally Posted by IC2

I guess that the next step will have to wait until Sunday/Monday - I got up at 0 dark 30 this morning and have driven to the furthest corner of Virginia from home, 677 miles. When I left home, no trace of odor, but......more to come, I'm sure:HMMM:.

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Did you drive the roadster?

well i think it you coil up15 feet of hose lay on top of the tank off the nipple and then run it up thru the trunk till you go up as hi as you can then a 90 run it back out . use a vented cap that should do the job that would be over 20 feet that should do it..... over kill you bet yep i maybe kidding here but not to much if your talking a J bend you could very well start in back of trunk run it up going forward till the back panle of the back of your seat hide it under your side trim of the 1/4 panle hook it to trunk drip rail then run it on the upper back side of the top of the rear 1/4 panle running the hose back thru the hole were it came and then out give you more then a J bend and if the tank get hot and fuel move s up that what really going on here with that low vent point on the tank every time you hit the brakes or if you sitting on a low front rake she going to want to siphon the the vent should be at the hi point of tank just a bad deal less it has some trick baffle and if so its not working very good ?

Dave,
Did you get rid of your gas odor in the garage? I installed a rollover vent extension like yours to be sure I'm above the liquid, but I ran my vent hose out at the 90 and down to a fitting in the floor. I'm getting a strong gas odor, and I guess I need to put a "J" loop in the tubing to hopefully stop the fumes.

Roger - occasionally I'll still get a gas odor, but for the most part gone.

I have some today, but I just had much of my gas line apart for replacement of some "claptrap" so might have a minor leak - which I'm abut to check

This is really strange. After reading the entire thread I can't imagine what would make fumes like that. We had 3 of our cars sitting in the shop with fuel in the tanks and never get any hint of gas odor. We even have one open jerry can that Dan has been using to draw gas out of for his RPU and no fumes from that one either.

My 23 just had a simple vented cap,and my 27 and Dons T have simple hose loops out of the tank vents. Very strange that you are having that issue. :confused:

Don

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Originally Posted by Itoldyouso

This is really strange. After reading the entire thread I can't imagine what would make fumes like that. We had 3 of our cars sitting in the shop with fuel in the tanks and never get any hint of gas odor. We even have one open jerry can that Dan has been using to draw gas out of for his RPU and no fumes from that one either.

My 23 just had a simple vented cap,and my 27 and Dons T have simple hose loops out of the tank vents. Very strange that you are having that issue. :confused:

Don

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Don - that vented gas cap may be what I need to install. I shouldn't need one with the rollover valve, but that's about the only thing I haven't done since I don't have a spare plus I really don't want gas to slop on my nicely painted '32 style gas tank (it's a '71 Jimmie cap, I believe that Tanks supplies)

I never had a problem with my '23 either and that only had a roll over valve and an unvented early Jag(?) flip open cap.

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Originally Posted by Louey

Have you thought about using a small charcoal canister ? To store the fumes, until you start, and run the engine ?

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I still can't understand why any of that would be necessary. On our stuff we are running nothing special, just looped hose or not even that, just vented caps, and not a whiff of odor. Something is odd with this one IMO, maybe that rollover thingie is doing something strange. :confused: I could stand right behind any of our cars and even remove the caps and get no smell.

Don

Just a thought, maybe the heat from the exhaust is just enough to expand the gas to start a siphoning cycle, its happened on my `64 pu, with the tank in the cab, on a real hot day, pushed the gas right past the cap and ran back down the filler tube into the cab, it was bad for a week...:whacked:

Could it be that with a vented cap the odours are released slowly but with a non vented cap pressure builds up and then releases quickly make the odour more pronounced ??? just an idea

Steve - that's a thought as well, but until I get a spare 'petrol' cap am not going to start drilling holes yet.

I just went through my partially replumbed gas line and no leaks. Interesting that the Edelbrock carb seemed to have a slight gas odor around it so I did snug the input fuel line just a tad - but it does make me wonder about the carb itself. This is/was a brand new carb and all of the settings were checked when I originally set it up identical to an earlier carb that was on a 351W. I don't have a pressure regulator on it, but possibly it needs one as I have no idea what my fuel pressure is except that the Carter mechanical fuel pump was supposed to be the 6psig version - (hmmmm more AN fittings) The gas cap was loose so that might account for some odor. That cap does have a check valve to allow air in, but not out.

Oh well - gonna reset the coil overs and shock adjustments as I've procrastinated long enough about crawling under the car:o.

I just talked to Lee at Tanks, Inc and learned a few things. First, my billet cap did not have the thick o-ring gasket, so my odor in the trunk is most likely due to my cap not being sealed. Tanks is sending me an O-ring which they say is very thick and heavy, rated for fuel service.

Second, their brass anti-rollover valve actually is designed to fit down into the tank as it has two check balls - one is phenolic and floats up to seal the vent with slosh with a full tank (not supposed to be topped off, but if it is...), and the second is stainless to drop down if the tank/valve becomes inverted. Mounting it extended above the tank is fine, but Tanks does not consider that to be necessary with their dual check ball design.

Lee says that it is normal and expected to have a slight gas odor from the vent in a closed garage, especially as the tank warms as ambient temperatures increase since our applications do not have the modern OEM vapor recovery systems and charcoal filters.

Hopefully the O-ring gets rid of a lot of my gas aroma, and I am still going to get a longer hose for a up & down loop seal.

Those billet caps can be a PITA on a steel filler neck. Crossthreads, galling, etc. I had to replace mine because Gibbon had cross-threaded it. Every now and then, I put a little anti-seize on the threads.

I also installed the Tanks, Inc. rollover valve, and once I replaced the cap, I had no gas odor.

Since I don't have a billet cap, I can't blame that:LOL: Tanks was temporarily out of production of that filler when I bought my tank. And like Jack said, they have been a problem for a friend and his '32. Gas odor - mine is like Chanel #5 perfume compared to his!!!

Since I'm doing a bunch of other punch list items on my car, I'm rerouting my vent line - again, this time in a more permanent fashion, but since there was no gas odor today...............damn:eek:

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Originally Posted by rspears

I just talked to Lee at Tanks, Inc and learned a few things. First, my billet cap did not have the thick o-ring gasket, so my odor in the trunk is most likely due to my cap not being sealed. Tanks is sending me an O-ring which they say is very thick and heavy, rated for fuel service.

Second, their brass anti-rollover valve actually is designed to fit down into the tank as it has two check balls - one is phenolic and floats up to seal the vent with slosh with a full tank (not supposed to be topped off, but if it is...), and the second is stainless to drop down if the tank/valve becomes inverted. Mounting it extended above the tank is fine, but Tanks does not consider that to be necessary with their dual check ball design.

Hopefully the O-ring gets rid of a lot of my gas aroma, and I am still going to get a longer hose for a up & down loop seal.

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I used this same valve and have it mounted externally on a short section of hose. No loops in the line and no odors found. I also have the aluminum cap with the heavy o-ring on a steel neck and haven't had any problems. I also apply never-sieze out of habit!

IC2 -
I have a below the bed tank on my 48 truck. My vent line only raises maybe two inches. I've had gas in the tank for a year now, with no fume problems, except in the beginning, when I installed the fuel line. Turned out the fitting into my tank(on the bottom) had a small leak where it dripped very slowly, so it was hard to tell, but boy what a stink. I'm posting here mostly to get updates so I can follow this thread. Problems like these drive people nuts. It's always good to see them fixed! Hope all your efforts pay off. It may also not reoccur until next time it heats up enough for the tank to expand, now that we are headed into cooler weather. Hang in there.

I read this thread six months ago and installed a length of fuel line along the inside of the right rear quarter panel up over the highest 1" square tubing bar in my Bebops roadster. I still have a garage gasoline odor and I am going to check my installation against every aspect mentioned here.

Don Shillady
Retired Scientist/teen rodder

If its an odor in the garage don't overlook lawn mowers, snow blowers, rotor tillers,leaf blowers or possibly some gas can-----------

Also don't forget the spouse after burrito night!;)

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Originally Posted by Don Shillady

I read this thread six months ago and installed a length of fuel line along the inside of the right rear quarter panel up over the highest 1" square tubing bar in my Bebops roadster. I still have a garage gasoline odor and I am going to check my installation against every aspect mentioned here.

Don Shillady
Retired Scientist/teen rodder

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Something that gets overlooked quite a bit is two fold, the first being a fuel line not compatible with modern day fuels. The second is a gas cap that no longer stays seated and sealed.


Bill S.

I waited until the temp went up this afternoon and found two items. First, I checked with Rock Valley Antique Auto who made my tank out of 14 gauge stainless and found I did not have any rubber O-ring in the screw-on cap. "Chris" of Rock Valley said "without doubt" there will be a gas smell without that gasket/sealer so I ordered the recommended O-ring. Second, I checked the end of the vent hose and found it slightly moist with gas. Note that I had topped off the tank three times two weeks ago during mileage tests so with the level of gas slightly up in the neck of the fill pipe vibration could have sent liquid up the vent hose. My vent hose goes steadily upward from the front corner of the tank over the 1" square tubing under the rear deck about 12-14" above the tank and then down to a hole in the floor under the right rear fender about at the front edge of the right rear tire. This looks a lot like a siphon until there is a vapor gap at the tank level so I probably did lose some gas through that tube. When I came into the garage this morning the gas odor was very slight and much less than when I was doing the fill-ups for the mileage tests. I also got the hint to put some anti-seize grease on the threads of the cap, thanks for that suggestion. I think the recent smell was due to the topping off of the tank right into the neck during my mileage tests so let me see if the O-ring and less-than-totally full levels reduce any smell. Jerry's comment is accurate since I have a wooden floor in my garage and there have been many spills of rear gear oil, a LOT of spilled prestone and some motor oil spills that have soaked into the wood! Thanks for a lot of helpful comments on this thread.

Don Shillady
Retired Scientist/teen rodder