Expansion tank bypass

[classic240z]

The hoses going from my fuel tank to the expansion tank are all rotted and leaking. My Z is a daily driver so I don't have time to pull the tank and replace the hoses. I cut and plugged all but one hose and routed it to the filler neck hoping that would be enough ventilation for it, but it takes about ten minutes to get all the gas squeezed in it will take. There seems to be an air pocket in the top of the tank; from bone dry to full (for it) is only about twelve gallons. Maybe thats full, but someone told me it should hold more like fourteen. Any ideas on what to do (other than replace every hose)?

Thanks,

Classic240z

[2ManyZs]

By all means, replace the hoses!! Some of the hoses can be replaced with fuel line if you don't want to spend the money for the original replacement hoses. Motorsport Auto has the hoses you will need. They are expensive, but a couple of the hoses have curves that a regular fuel line will not make without pinching shut.

I would be very nervous with the hoses plugged off. By doing this you may be building pressure in the tank which could lead to a disaster. Not only is there no way to vent the gas fumes but by having gas being returned to the tank you may build up quite a bit of pressure in the tank if your gas cap does not vent.

A 240 gas tank should hold 16 gallons. I believe the 280's held about a gallon more.

[Mike]

Yes, certainly replace the hoses. Don't just cap them off.

I wasn't able to find fuel hose that size. I just used some black heater hose. I found it in bulk at my local auto store.

I was concerned about using the heater hose due to fuel deterioration. However, I came to the conclusion that the heater hose is ok because these hoses are used to carry fuel vapor (not fuel itself).

[EScanlon]

In their Premiere issue Sport Z Magazine had an excellent article on replacing the fuel tank vent hoses. The author even went to the trouble of providing the part numbers from a McMaster Carr catalog.

I found you can get all but one of the hoses from NAPA. The only hose you can't get is the 1.25" hose that goes from the top of the filler neck to the vapor recovery tank. The biggest problem you may encounter is in getting a couple of the hoses to effect the tight 180° turn. You can however, get metal springs in the right diameter to fit snugly inside the hose which will allow you to bend the hose without kinking it.

It's most important to remember that the tank has three vent orifices that connect to the recovery tank. The recovery tank has 5 orifices. The extra two go to the filler neck and to the return line from the engine compartment.

By plugging the lines at the recovery tank you've made it so that only so much gas can get into the tank before it starts compressing the air bubble above the gas. Additionally, you've also plugged one of the vent lines from the engine compartment. Don't know what that could / will do, you'll have to ask one of the engine guru's but you're taking a short cut that may lead to trouble down the road.

Yes it is a pain to have to drop the tank to get to the hoses, but the end result should be a better smelling vehicle after filling your tank, and it will also allow you to clean under the rear deck and avoid any rust problems later.

Hey, it's just my 2¢ worth.

[classic240z]

I appriciate all the information. I figured most responses would be "pull the tank". I've had the hoses plugged since I first started driving the car seven years ago. It's done fine other than not holding a full tank of fuel. So as much as I hate to do it, I guess I'll just do it right. Thanks a lot...and if anybody wants to come to Oklahoma City to do this for me; feel free!

[Daniel]

The longest most expensive /most problem to replace/one that causes the interior fuel smell is the one across the back under the rear panel that hides the taillights.I was told once that that hose was a calif. emission thing .I don't know if thats true.Anyway I removed mine and plugged it off at the tank and the exp. tank.The tank is taller on the fuel inlet side.That hose is on the low side.Any air would go to the high side.My 73 has been without that hose since 1976.I would use all three of the other vent connections.The tank is easy to remove.If you do pull it out may I suggest go ahead and have it cleaned out and dipped.Then you will never touch it again.

[Mike]

I own a '71 and it has a plastic fuel vapor recovery tank. This tank sits behind the plastic panel on the right side of the car (near the fuel filler).

After I pulled the plastic panel, I discovered that the inlet connection to the recovery tank was CRACKED and broken. This was a large cause of fuel smell in my Z. It was especially bad when I filled the car completely. Thus, I had to fill it only 3/4 to keep the smell down.

I also had exhaust smell in my Z, but, that's a different issue I can cover in another post.

[kmack]

Go ahead and replace the hoses.

And do not use heater hose. I used that initially, but still had to replace them a few years down the road. The fuel vapors will harden the heater hose and cause it to crack, causing leaks.

The only 2 hoses I've ever seen that needed to be replaced are the long 1/2" hose and the 5/8" hose w/ 180 degree bend. The short 1-1/4" hose from the filler neck to the expansion tank typically is fine. (I've looked at over 10 cars in junk yards and on everyone of them this hose was fine.) The 1/2" & 5/8" hose can be bought at any NAPA store for around $1.25 per foot. Not bad, but not cheap. Make sure you get the fuel line grade hose.

I bought 5' of the 5/8" and 8' of the 1/2" hose when I did mine just to be on the safe side. To make the 180 degree bend you'll need a piece if 1/2" OD steel tubing (preferrably stainless) about 6" long. (Do not use copper tubing! The fuel will degrade the copper over time and could ruin your fuel system.) You can probably find a place that sells this (plumbing shop would be a good place to start) and they'll most likely be able to bend it for you. I used a bench mounted vise. Painfull and time consuming, but it worked. Once you have the tubing bent, just slide it in the 5/8" hose and hook it all up. It's pretty easy from there.

While you're at it, you might as well replace the 3/8" hose going to the hard fuel lines and to the carbs if they haven't been changed already.

Good luck and don't forget to drain the gas tank! It's amazing how heavy about 8 gallons of gas feels when it's sitting on your chest! Don't ask....

[EScanlon]

Definitely drain the gas tank! And what's more don't just use the hose syphon method and hope that that got all the gas out.

The gas tank has a drain hole pretty much at it's lowest point. If you have the car up on jacks or on ramps then IT IS NO LONGER THE LOWEST POINT.

Like you found out, gas can be heavy, and when you are finally lowering the tank it's easy to think that, geez the tank is heavy. Only to discover that OH SHEET! as a gallon or so of gas suddenly spills all over your garage / driveway.:eek: I won't ask Kmack about his 8 gallons of gas if you promise not to ask about how the carpet in the garage smells. (A note aside, do you know how long it takes to get a gallon of gas to dissipate out of a garage?? Especially when it's cold?? NOT FUN!! And no matter how much you like to work on cars, there's something about the overpowering smell of gasoline that just ... :sick: )

As it is, you know you're going to have some spillage, but not more than a little bit. So keep this in mind.

By the way Mike, the later 71 and 72 recovery tanks were metal, unless you are going for concours restoration, get the metal one, also, unless they pop the panel, how are they going to know?

[240z72]

I did my hoses last month after reading the old post from z car.com. So here goes, first off you do not need to drop the tank. If kyou place molding door or floor between the rear part of the tank and the body you will get a little more room for the hose in on the rear passanger side. I would only use the hose from motor sport about $60.oo this will save you more in time and energy which will make up for the price ie well worth the $60.00. All the rest of the hoses can be bought at napa except for the one foot hose which probably does not need to be change.I did because i orded some of the hose from the place listed in above posts. I did not even have to put the car on a lift to do it .good luck

[jdowen2]

I just dropped my tank and found most of the hoses were hard and splitting. The hoses routed through the floor and behind the taillight panel had a splice in it (hose clamp, tubing, hose clamp). I called a few Z car parts places and almost died when I heard the prices. I was talking this over with a friend at work and he suggested trying a Marine supply store. I picked up the larger hoses that are Coast Guard fuel rated and got the smaller diameter hoses at NAPA. I am going to use a plumbing 90 degree elbow for the one bend near the expansion tank. While I had the tank removed I used POR-15 fuel tank repair kit and cleaned, etched and sealed it for $50.00.

[Mike]

Originally posted by EScanlon

By the way Mike, the later 71 and 72 recovery tanks were metal, unless you are going for concours restoration, get the metal one, also, unless they pop the panel, how are they going to know?

Hmm... really? Maybe the metal tank someone sent me is from a '72 or later car. Because it just didn't want to fit.

If I can find a metal tank for my project, I don't mind using it. I just didn't want to pay over $150 for a new one. At that time, I just had to draw the line on expenses.

My metal tank was 'donated' to me, so, I'll offer the same to someone else. More than likely, it's for a '72.

[m]