Fuel vent line hoses/fuel smell inside car!!!

[jvandyke]

Originally Posted by OriginalOpelGTOwner I replaced my fuel tank vent hoses last spring with 5/16 ID fuel line. To route line through hole in the floor pan there is a clearance depression in the crossmember located just inboard of the left side market lamp for the vent line. Did you try routing the line pass the crossmember at the depression?

I routed it just like OEM (unless someone preceded me in this, which I doubt), which was down right in front of the driver's side brake light, under the tank then out a hole right near where the fuel line to carb is located. The hole through the chassis is too small for this tube (as has been said before). (Enlarging it scared me, anything sparky with all those fumes floating around is kinda scary)
(I think the diagram shows slightly different set up in '73)
Anyway, I got it down. What I'm going to do with the "loose end" under the car I don't know. PO had it just sitting there too. I sure hope this solves my gassyness (the burritos don't help either).

PS had to search to find that the nuts to release the tire/jack bracket that sits on the shelf on passenger side (has to come out to get shelf out) were in the rear wheel well, above the tire, on the outside of the car (for the benefit of those that are doing this in the future) the heads for these bolts are smooth like rivets.

[Crazy Harry]

I replaced my vent lines with fuel line as well. I didn't have to remove the tire bracket mount on the passenger to get the shelf out.

The gas smell is significantly less now, but not completely gone. Any other suggestions Does one have to change any other components back there, like the rubber section between the tank and the filler neck or a fuel level sending unit seal? I think my charcoal canister in the front has a leak, looks like rust got to it, would that make a difference?

Thanks,
Harold.

[OpelJim]

Originally Posted by jvandyke Yep, I've read up on this and downloaded the diagrams and all that, 5/16" fuel line, clamps. Don't recall about how many feet it takes now, anyone remember? Also, at some point to get through the body 5/16 was tight, maybe splice a little section of someting a bit narrow there? I have to go look through all my stuff again. I suspect as soon as I lower the car I'm okay for the moment. Probably pouring out the top left line, gas is way too expensive for this loss! http://clubs.hemmings.com/clubsites/...h/TankVent.pdf from another thread

I read Charles Goin's repair information and it is very good advise with the exception of the "5/16 th Tees" you can use from a local hardware store

The one "Tee" off the filler neck has a small pin hole opening on one side and a larger hole on the other.
There is a design reason that small hole has to be mounted towards the neck This is to lessen the amount of gas that will flow down the line when filling the tank, and lessen the vapors that go into the compartment.
If anyone wants the tech tip from Jim Petzold with instructions on how to do the repair and an easy to understand illustration too I can send them copies.

[rsefczek]

i could definitely use that explanation, jim. p.m. or personal email?

bob

[BDD]

I need that tech. sheet and explanation too.

The info. that I have shows the small opening in the tee valve, NOT in the line to the filler cap but in the tee at the line thta goes to the charcoal canister to reduce chance of gas going that way.

What size does this opening have to be? Only vapor moves through it.

Can any old tee be used, just put a press fit metal tube in that end of the tee to limit that particular orifice size?

[Anonymous D]

"Does one have to change any other components back there, like the rubber section between the tank and the filler neck or a fuel level sending unit seal? I think my charcoal canister in the front has a leak, looks like rust got to it, would that make a difference?"

In answer to your questions:

(1) Yes, there are other components involved, and it's a good idea in general, to just go ahead and replace the wide hose between the tank and filler neck tube, and to also replace the gas tank sender gasket, at the same time as you have done the labor to access the hoses off the fuel tank. I have experienced an ongoing fuel smell, even after replacing the vent hoses and clamping them off, which wasn't stopped until I took those extra steps. In many cases, these are 34-38 year-old original components that are asked to prevent a possible explosion! Certainly it's worth an extra $20 for the parts, to eliminate that scenario.

(2) It's a good idea to also connect the carbon cannister line to the tank. It helps to reduce tank pressure buildup, by providing a filtered outlet for fumes to be vented out. (Also understand, that when you rely on a tech tip, that you need to verify that the writer has actually performed the procedure and has monitored its longer term results on an actual GT. Badly written tips, which have been observed in the past, can invite complications and even injury. Variables can also include profit motives, publication deadlines, the degree (or lack) of social responsibility of the writer, and individual ego).

[carter840]

Well I want to drain my fuel tank but i can't seem to unscrew the plug in the bottom of the tank i have tried all types of sprays to loosen it but nothing has worked. Can anyone suggest another way to drain the tank i have 8 year old gas in there now that i want to get rid of. Also i noticed as well that the vent lines on the tank have fallen apart can someone recomend a good replacement hos that will work as a recplacement?

[namba209]

You can drain the tank by removing the fuel line where it attaches to the metal tube coming out of the tank. I would put a short piece of hose over the metal tube, so you can squeeze it closed or plug it to stop the fuel running out if needed. The replacment vent line hose has been discused numerous times on the site, do a search for fuel tank vent lines and you'll find a lot of posts on it, also make sure you put the "T" fitting back in the correct position when you replace the lines, there are different size holes in them for a reason. HTH.

[West Coast GT]

I've found no good way to dispose of old fuel once it's drained from a fuel tank. The 3 times I've had this issue, I've left it in the tank and followed the following procedure;

1. I install one of those semitransparent white plastic cheap fuel filters in the easiest accessible location (under the back of the car)
2. Top the fuel tank off with good fuel,
3. Add a can of fuel additive to absorb the moisture,
4. And burn the fuel through the engine.
5. Change the cheap filter when it appears clogged.
6. Add more good fuel as needed to further dilute the bad fuel.

I change the cheap filter and leave it on for a tank or two just to make sure I've captured all the crud. Then remove the filter and trust your real filter to do its job.

No Muss, No Fuss.

[George]

Do you have to take the tire shelf out to see the holes in the tee or can I go in through the taillights?I just replaced all the vent hose and didn't know the tee had two different size holes.

[baronbors]

Originally Posted by George Do you have to take the tire shelf out to see the holes in the tee or can I go in through the taillights?I just replaced all the vent hose and didn't know the tee had two different size holes.

You can go through the tail light openings unless you have huge forearms (like me- thanks to my lovely wife for her kind assistance) It is much easier through the storage compartment with the platform out-BTW- check the gasket on the fuel sending unit with the plywood out.

[carter840]

OK so today i wanted to drain my gas tank so i took out the spare tire rack just to make sure it wasn't rotted to bad. AND as most of you also saw, i saw that the vent lines where broken. Does anyone have a diagram of what all of the ports on the tank are and where the hoses go. I think i have it all down except there is one hose in the back right (from inside the cabin) that goes down (it seems like under the car)-->what does this line do and where does it go. Also on the T fitting that goes to where you put the fuel in i am unsure about where one of the lines goes. I know one goes to another T fitting but what about the other one? I do have a service book for my 1973 opel and i also have a Chiltons book niether of them have helped me with these questions maybe some of you can. Hope that wasn't to confusing. Also i replaced the line with low pressure hose from my local car quest store it was cheap at only 1.50 a foot.

Also good news i got the engine running today, well 3 out of 4 cylinders. Tomorrow i change the spark plugs and a few other things.

[jvandyke]

Here's a pdf of it, if this works.

[West Coast GT]

Originally Posted by carter840 ... I think i have it all down except there is one hose in the back right (from inside the cabin) that goes down (it seems like under the car)-->what does this line do and where does it go.

If it's transparent, or opaque from age, approximately 1 5/8 inch diameter, I believe you might be looking at a rain-water drain line.

Could some of you more experienced members confirm?

[MarkRHayes]

Originally Posted by jvandyke Yep, I've read up on this and downloaded the diagrams and all that, 5/16" fuel line, clamps. Don't recall about how many feet it takes now, anyone remember? Also, at some point to get through the body 5/16 was tight, maybe splice a little section of someting a bit narrow there? I have to go look through all my stuff again. I suspect as soon as I lower the car I'm okay for the moment. Probably pouring out the top left line, gas is way too expensive for this loss! http://clubs.hemmings.com/clubsites/...h/TankVent.pdf from another thread

thanks for the diagram, i've just replaced my fuel line hoses. one question. what are those two fatter hoses on either side of the gas tank supposed to be? it looks like they both are on the extreme left and right of the tank and tend to go forward to something but aren't connected to the gas tank in any way?

[jvandyke]

Those are water drains from the cabin vent system, from the vents on the outside above the rear window, that whole thing. They go through the bottom of the car and have "duck bill" rubber caps so water can get out but fumes/ junk can't get back up in there. I still have issues, either the T fitting with the smaller opening is in wrong or the filler neck is vapory....almost there.

[MarkRHayes]

where is hudsonville, jv? i'm in berkley, a suburb of detroit on 12 mile?

[jvandyke]

Originally Posted by MarkRHayes where is hudsonville, jv? i'm in berkley, a suburb of detroit on 12 mile?

Hudsonville is on the west side, near Grand Rapids. Michigan Opel people need a gathering next year.

[newman27]

I've had an interesting issue arise that resulted from an odd sequence of events so I thought I would post them here as I think they relate to the vent line issues discussed in this thread. Also, this may help someone else in the future because it is rather odd (to me anyway)...

My car started bucking and stalling recently for no apparent reason. After much discussion and investigation, including test driving under various conditions, it turns out that a vacuum is forming in my gas tank. Once the tank gets down to about half full, the problem starts and gets worse as the tank is drained. The only thing I changed on the car was to put on a nice new gas cap. It would appear that this new gas cap has revealed an issue with my vent lines. The new gas cap is forming such a nice seal compared to my old POS gas cap, that a vacuum is forming inside the tank (that is my current working theory). What clued me in to this was the fact that a loud hiss of air is released from the tank when the new gas cap is removed which is something that never happened with the old gas cap. In addition, while replacing a burnt out side marker bulb on the driver side, I noticed that the driver side vent tube is full of fuel!

So, on to the questions...

Originally Posted by jvandyke ...Gas actually poured out of the passenger side vent hose when I pulled it off the tank. I guess if you really fill this tank up, you fill up the vent lines too, as you can fill the filler neck, you could have gas in the vent lines quite high (probably why the lines are clipped to the roof of the compartment, to keep them high...

I think I have managed to overfill the tank - that is my theory on how the vent line became full of fuel (although I stick the pump nozzle as far as it will go into the filler neck when filling up and do not "top off" once it clicks off). I assume as I drive the car, the fuel in the vent line will drain into the tank as the level in the tank decreases. Or, is it possible for the vent lines to hold fuel permanently? If so, that must be the reason the vacuum is forming in the tank. If not, then is it a gas cap issue and I need to vent that gas cap somehow? I'm basically looking for folks that have had their vent line fill up with fuel relate what they did once discovering the issue. Clearly, I don't want this to happen again.

Originally Posted by OpelJim I read Charles Goin's repair information and it is very good advise with the exception of the "5/16 th Tees" you can use from a local hardware store. The one "Tee" off the filler neck has a small pin hole opening on one side and a larger hole on the other. There is a design reason that small hole has to be mounted towards the neck This is to lessen the amount of gas that will flow down the line when filling the tank, and lessen the vapors that go into the compartment. If anyone wants the tech tip from Jim Petzold with instructions on how to do the repair and an easy to understand illustration too I can send them copies.

I read this thread and Charles' information but couldn't find the tech tip from Jim Petzold. Is it posted somewhere here?

I know the subject of the vent lines has been discussed ad nauseam but I thought this particular sequence of events involving the gas cap and the vacuum situation in the tank might be of interest. I also want to know if I should do more than just drain the vent line that is full of fuel, stop filling the tank all the way up, and move on. Comments and suggestions appreciated!

Thanks,

Matt

[namba209]

That's interesting, and I've heard of it happening before. I'm trying to think if the original GT gas cap is a non-vented or vented type. After looking at Willit?s cap it appears to be a vented type, but I'm not sure. So that begs the question, do you have an original cap or after market, and if aftermarket, is it a vented or non-vented? Looking at the routing of the vent lines, and presuming all is functional, the flow of vacuum presumably would be, starting at the intake manifold/carb, to the charcoal cannister, back to the gas tank, through the tank vent lines and in from the gas cap. Again presuming, equal vacuum in the tank and vent lines, the fuel sloshed in to the vent lines down low at the tank would eventually drain back in to the tank, because they are mounted under the floor of the rear window shelf. So it says in the fine print. The tech tip that Jim M. of USA Opel has is not loaded on the site, he infers he has copies he can send out. HTH.

[newman27]

Originally Posted by namba209 That's interesting, and I've heard of it happening before. I'm trying to think if the original GT gas cap is a non-vented or vented type. After looking at Willit?s cap it appears to be a vented type, but I'm not sure. So that begs the question, do you have an original cap or after market, and if aftermarket, is it a vented or non-vented? Looking at the routing of the vent lines, and presuming all is functional, the flow of vacuum presumably would be, starting at the intake manifold/carb, to the charcoal cannister, back to the gas tank, through the tank vent lines and in from the gas cap. Again presuming, equal vacuum in the tank and vent lines, the fuel sloshed in to the vent lines down low at the tank would eventually drain back in to the tank, because they are mounted under the floor of the rear window shelf. So it says in the fine print. The tech tip that Jim M. of USA Opel has is not loaded on the site, he infers he has copies he can send out. HTH.

I'm using an NOS Opel gas cap. I have no idea if it is vented or not. Also, I no longer have the charcoal canister so my set-up is not stock. It is an interesting scenario. Right now, I am just letting the air out of the tank every now and then by opening the gas cap. I can do that as long as necessary until I figure out the correct solution. I'm just happy to have narrowed it down to this. Any other thoughts much appreciated...

Thanks!

Matt

[ungermm]

I tested 2 of my original gas caps and they both seem to be vented. Your cap must not be vented by the fact that there is a vacuum being created. I would think the vent lines would help to alleviate any vacuum. However, if they were blocked you would get the symptoms you are describing with a non-vented cap. And, since you have fuel in the vent line, it does make sense that you have an overfill situation. I would check the vapor cannister and see if it has fuel in it also. I'm not sure, but I can imagine that if fuel got it there it would block up the whole system.
Jerry

[ungermm]

Oh, didn't see you didn't have the cannister. Where do your vent lines go then?

[kwilford]

The OEM Opel gas caps are non-vented, to minimize gasoline vapour emissions, hence the evaporative system (vent lines, charcoal cannister and connection to the carb throat). If your vent lines are plugged, it would certainly cause the tank to pull a vacuum, and starve the fuel pump and carb for gas. I wouldn't have thought that gasoline in the vent lines would block the lines enough to pull the tank into a vacuum, but perhaps. As ungerman has asked, what are you doing with the vent lines if your cannister is removed?

[tomking]

I agree with KWilford, just having fuel in the vent line should not cause it to pull this much vacuum. It suggests your vent line is plugged or kinked and therefore NOT venting.