Fuel Smell

[namba209]

Originally Posted by jvandyke (and gas smell after fill up)

Jeff, that sounds like the proverbial vent lines leak, or worse yet, like I had in Willit? the hose between the filler neck and tank.

[jvandyke]

Yes, I redid the tank vent lines but either the filler neck or fuel level sender unit gasket or T fitting small orifice is wrong, I need to do more work yet. that and fix the oil leak to hopefully kill more "fumes" hot motor smells, sorry getting OT.

[tomking]

It can also be the fuel outlet connection leaking and making the smell.

[wattiefan]

When i bought my 72 gt there was a god awful fuel smell in the car. It turns out the po had "tried" to repair the fuel sending unit but made it longer so it stuck out of the tank about an inch. So by using longer bolts and a thicker gasket, he turned a little task into a dangerous cituation. That was my culprit. After new gasket and sending unit, no more fuel smell

[kwilford]

Posts split off from the Pace-Setter Header Thread (), as if we really needed another one of these threads

[newman27]

Originally Posted by jvandyke Yes, I redid the tank vent lines but either the filler neck or fuel level sender unit gasket or T fitting small orifice is wrong, I need to do more work yet. that and fix the oil leak to hopefully kill more "fumes" hot motor smells, sorry getting OT.

The first couple tanks of gas I ran through my GT I had the fuel smell pretty bad until it got down to about 1/2 tank. On about the third tank full, the fumes were not present and have not returned. While I can't explain it, I mention this because after each fix you apply to the problem, you may want to run a half tank or two to see if the smell dissipates before you go looking for another issue.

Matt

[blancojp]

Most of the fuel smell cases come from not installing the fuel vent properly. Without the vent, gas fumes will enter the car while the tank is full. After a few days and the tank goes down, the smell goes partly away.

[jvandyke]

What could be improper? I found out (expost facto) about the odd ball T fitting. I broke one of the OEM ones and just got one from the hardware store , now I understand one opening in the T is quite small and that one is supposed to point to the filler neck, so I probably did not get the right T in the spot. I have to check that although I don't "get it", so what if some gas goes down that tube it "should" just go back to the tank and the whole system is "sealed". I did all 5/16" fuel line and screw down clamps, followed old routing pattern. I probably have issues with the filler neck or sending unit gasket.

I'll have time to tinker now, as I backed out of the garage in the GT it started to rain, prediction is for 40 mph winds, rain and snow mix later today. I took the sign and pulled the GT back in, reluctantly taking the Intrepid instead.
Party's over for the season. I've opted to keep the GT in my Intrepid's stall over the winter so I can tinker at will. Poor Dodge. Poor JoAnna, she's up in the UP where winter is arriving with a vengeance. I hate winter.

[OriginalOpelGTOwner]

My thoughts on the function of the "T" fitting. When I replaced my fuel vent lines I did notice that the "t" fitting had a small orfice that was on the side of the "t" fitting that hooks up to the line to the filler pipe. My understanding is that when you fill the tank the small orfice prevents fuel from entering the vent lines and allows trapped air in the tank to vent through the vent lines which might not vent back up the fuel filler pipe. Other than that any "T" fitting will function properly while not filling that tank with fuel. Another source of gas fumes are micro pin holes in the tank sheet metal, mainly where the steel pipes for the vent tubes are brazed to the tank.

[jvandyke]

There's another thread going now discussing the charcoal canister, my line had been cut by the rear axle and just open to the air. I replaced all the line with hose but also just left it open to the air down there. Wondering now if I should put some sort of canister on there.

[kwilford]

Originally Posted by jvandyke There's another thread going now discussing the charcoal canister, my line had been cut by the rear axle and just open to the air. I replaced all the line with hose but also just left it open to the air down there. Wondering now if I should put some sort of canister on there.

OK, I am a bit amazed that you thought the fuel smell wasn't related to the gas tank vent just dumping vapours under the car. The only way to finally get rid of the gas smell is to install a charcoal cannister ANYWHERE in the vent line ON THE WAY TO THE CARB. The cannister merely stores vapours when the tank vents during the periods of time the engine isn't running. When the engine starts (or is simply running), the vapours from the cannister (or directly from the tank) gets ingested into the carb, where they are burned. There are probably 10 links to the tank vent system somewhere here, so I won't go looking for it, not to mention at least five threads of how to hook a Weber up to the cannister. If you allow tank vapours to simply vent outside and not into the carb intake, it isn't a matter of "if" you smell gas fumes, but "when".

[jvandyke]

Originally Posted by kwilford OK, I am a bit amazed that you thought the fuel smell wasn't related to the gas tank vent just dumping vapours under the car.

Oh, my ability to amaze is, well, amazing!
Somewhere I picked up that as long as it was outside the car no biggee. Obviously that's NOT conventional Opel wisdom. I'll hunt down a canister and plumb it up to the Weber's air filter, T'd with the large valve cover as I've NOW read. I'm feeling a bit stupid over here, but I can take it.

wonder if this would work, Feiro

[kwilford]

Originally Posted by jvandyke Oh, my ability to amaze is, well, amazing!

Oops, sorry, too strong of words on my part

Some folks do what you have done, or even just disconnect the cannister up under the hood, and don't report gas vapours. But if you smell vapours, it is pretty easy to hook up the tank vent system so that they are burned, rather than allowed to waft carefree around your car, looking for an open window.

When "emissions controls" became a dirty word back in the mid seventies, a common reaction was to "rip tham damn commie hoses out and go back to what worked in the fifties when my pappie taght me haw to spl.." Except the Opel gas tank is sealed, hence the ventilation system, and it can become a concentrated source of gasoline vapours if left open. Worse, some folks just plugged them damn commie hoses (sorry, I am in the groove) and the tanks either over-pressured, or went into a vacuum and starved the fuel pump.

I guess I was thinking that this topic had been discussed so many times that it was "common knowledge". Sorry again, my bad

[jvandyke]

No problem. I'm going to stop by an "old car" place to see what they might have for a canister. Otherwise that Fiero one looks plausible and cheap ($30). I'm not quite sure if that's my whole problem though just because it seems worse in the car and you'd think it would smell outside the car, especially after sitting in a closed garage all night. I just have to go through it all again back by the tank. Can't help but wonder if you couldn't just run that line straight to a T in the little vacuum line between rocker cover and intake. If I'm understanding it, the canister is basically a holding tank for vapor that will get sucked into the intake when the engine is running. Not much vacuum when cruising so can't imagine you'd create a problem for fuel delivery. Also can't imagine fumes would find their way all the way UP (gas fumes prefer to go down anyway I believe) through that vacuum hose, through the intake and up through the closed throttle plates and become troublesome....just thinking out loud again.

[namba209]

Jeff, you do not want to "T" the fuel tank vent line to the smaller vacuum source fitting at the valve cover. You gotta remember the fuel tank is a sealed unit, it needs to be vented so fuel will flow out of it. If you put a vacuum source to the vent line, fuel will eventually cease to flow out of it. The modern charcoal cannisters have internal valving that will pull the fumes from the vent line, then allow the tank to be vented through the bottom or back plate of the cannister. HTH.

[George]

Originally Posted by jvandyke Yes, I redid the tank vent lines but either the filler neck or fuel level sender unit gasket or T fitting small orifice is wrong, I need to do more work yet. that and fix the oil leak to hopefully kill more "fumes" hot motor smells, sorry getting OT.

I just replaced all the vent lines with gas line hose.Where is this orifice at and what does it do?Would that be in the tee fitting close to the filler neck?

[kwilford]

Originally Posted by jvandyke Can't help but wonder if you couldn't just run that line straight to a T in the little vacuum line between rocker cover and intake. If I'm understanding it, the canister is basically a holding tank for vapor that will get sucked into the intake when the engine is running.

As Ron says, do NOT connect the tank vent to a vacuum line! That is a sure fired way to suck the tank down and FOR SURE lose fuel pump suction. In a stock Solex, the cannister outlet connects to a Solex-only port that vents directly into the throat of the carb. Since that is a Solex-only solution, the next best place on a Weber or Holley is anyplace downstream of the air filter, as the pressure drop across the filter is the ONLY amount of vacuum that the tank can tolerate and is sufficient to evacuate the cannister. Webers typically use a square filter that has a fitting in the base, that is inside the filter (i.e. between the filter and the carb throat). It's the same place that the large valve cover hose connects to on that kind of air filter. If you are using a stock GT Filter housing, then the cannister can connect to a tee in the large hose that connects to the snorkel.

HTH

[jvandyke]

Originally Posted by George I just replaced all the vent lines with gas line hose.Where is this orifice at and what does it do?Would that be in the tee fitting close to the filler neck?

Yes, supposedly, the T that comes off the tank filler neck has a small hole pointing toward the neck to discourage gas from going down that way during filling. When I redid my lines I did not know that and didn't pay attention so that might a problem in my case. Seems like you could just raise that line up a bit too so gas wouldn't go down it but I haven't looked back there since I messed with it all last spring to know if that's even possible.

[namba209]

Originally Posted by jvandyke Seems like you could just raise that line up a bit too so gas wouldn't go down it but I haven't looked back there since I messed with it all last spring to know if that's even possible.

Jeff, there's a couple of clips to hold the hoses, under the shelf below the rear window. without using the clips the hoses will fall and rest on the tank then get pinched by the spare tire shelf that goes on top of the tank. HTH.

[jvandyke]

Thanks Ron, I'll shut up until I can work on it, too easy to sit at work and raise conjecture all day (and waste peoples' time with posts like this )when the job itself would likely take 1/2 hour.

[namba209]

Originally Posted by jvandyke Thanks Ron, I'll shut up until I can work on it, too easy to sit at work and raise conjecture all day (and waste peoples' time with posts like this )when the job itself would likely take 1/2 hour.

Methinks it will take a bit longer than that Jeff, considering you'll have to pull the spare tire shelf out to access the area. But what the hey, it's called gaining experience.

[jvandyke]

I undid last spring's work. I took the T's out. I might have lucked out in that I broke the non-little orifice one, therefore I still have the T with the small hole if pic #1 is showing the little hole in there. Pic #2 shows the other passage through the T and it's wide open. I put it back the way it "should be": small opening toward filler neck. Another post with another pic to follow.

[jvandyke]

Here's a picture for posterity. That vent hose attaches so high on filler neck, could gas really get down there? Wouldn't it just run into the tank anyway? When I fill up I slow down the pump when I get close to full, then put the nozzle in deep so the cut off stays low and I don't get much if any gas up in the filler tube. Hose and gasket look fine and dry. Will likely just replace anyway, and hope there's no holes in the tank.

[jvandyke]

Took another look back there after driving to work in her today. Was obvious now that the whole top of the fuel level sending unit is wet with gas. Hmmm, that ain't right. Good excuse to work up another order to OGTS!

[jvandyke]

I resealed the sending unit and I still get fumes in the car after she sits shut up for a bit.
Revisiting the canister issue.
I've read through the threads but have some questions yet. (sorry if I've missed the answer).
Could one just run the tank vent line straight to the carb bowl vent port? (my 38 has one and it's open and I put a fitting in it (currently just capped).
Is there much of a vacuum situation in the float bowl chamber?
Or would this effectively "close up" the system creating a vacuum in the tank?
I guess it could.
I'm thinking of going to an adapter and stock filter housing intake. If so, where do you hook up the large valve cover line? Somewhere on the snorkel I read?
Does one really need a cannister I guess is the question too.
Normally the system would pull in replacement air for the tank through the carb throat fitting (Solex) through the cannister, back to the tank.
Weber: through the air filter housing (T-d at large valve cover hose) through the canister to the tank.
Weber via adapter and stock air filter/snorkel: through a T as with Weber filter, through canister to tank.
How about T on large hose at valve cover running straight to the tank, any needed make up air would come from with the air filter housing/snorkle or would that leave the possibility of fumes in the engine compartment?