Thread: Gasoline odor

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



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:

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.

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

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)

2 finger typing 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.

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)

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
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

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

Originally Posted by IC2

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



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

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.

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.

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

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

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.