The Fuel System of an air-cooled Volkswagen is not a complicated System.
But, there are some Fuel Issues which continue to plague the VW Community—some of them easily resolved with a little bit of thinking and work. These are things which most of us can do ourselves.
First, rather than running to all of the forums on the subject, it’s time to sit down to consider how the Fuel System of our Beetles works.
CAUTION: When working with Gasoline—ALWAYS work outdoors and away from any source of flame or spark!
The Fuel Tank:
Complaints about Gasoline Fumes are common. Two things usually contribute to Gasoline Odor in the Trunk. This Odor often penetrates to the Cabin area.
Let’s talk about the Tank Filler Neck. Note that there is a tiny Tube coming off the Neck
pointing towards the left side of the car. By removing the Gas Cap and looking into the Filler Neck, we can see the Tube protruding into the inside of the Filler Neck. Where it protrudes, it is slightly pinched. This is to limit the amount of liquid gasoline which can escape through the Tube. A tiny Rubber Vapor Hose (N203531—ID-2.0 mm/OD-3.5 mm) is pushed onto the tube where it exits the Filler Neck. It needs no clamp since it fits tightly and there is no pressure upon it. (Note: Vapor Hose also may be marketed as Vacuum Hose.)
The Vapor Hose loops back towards the driver, then back again to the front of the car where it is pushed through an opening and allowed to dangle several inches beneath the car. Thus, any Gasoline Vapors will exit beneath the car and will not escape through the Trunk area and into the Cabin. If the Vapor Hose is missing or improperly routed—Gasoline Vapors will permeate the Trunk area and pass into the Cabin. Be sure that the Hose is present and routed through the hole to beneath the car. 2 Hose Clips (111-201-261) keep the Vapor Hose stabilized on the Cowling Loop.
If the Tank Filler Neck Tube becomes plugged, gasoline will not flow properly from the Tank Outlet. Also, make certain that the Vapor Hose is not pinched or plugged.
The Fuel Sender:
If your car has an original factory Fuel Sender, most likely the Rubber Boot on the Sender Arm has deteriorated. When the Boot deteriorates, it allows Gasoline Fumes to leak into the Trunk Compartment and to penetrate the Cabin. There is no repair to this Boot and no replacement Boots are available. It is time to replace the Sender. Replacement Senders do not have a Boot—instead, they are manufactured in a manner which does not require the Boot.
A Clean Fuel Tank:
We want a clean Fuel Tank. What goes into the Fuel Tank will continue to pass through the Fuel System and into the Carburetor. So, we must keep an eye on our Fuel Tanks. If your Beetle’s Fuel Tank has not been cleaned in years, it is time to examine its contents. Usually by removing the Fuel Sender (5 screws), and using a strong flashlight, we owners can observe any gunk which may be deposited at the low point. The low point is where the debris will clog the Tank’s Outlet. If you observe gunk plugging the Tank—it’s time for Tank removal and cleaning. This requires the removal of the Fuel. Some of us will be unable to perform this operation. Most mechanic shops can handle this procedure. When the Sender is removed, the Sender Rubber Gasket-Seal (113-919-133) should be examined for any damage.
At the time the Tank is removed and cleaned, it is imperative to observe the Outlet Strainer (111-209-147A). The Outlet Strainer is a long, skinny fine-mesh strainer of brass or copper. The Strainer is pushed up into the Tank. Gunk accumulates at the lower part of the Strainer and begins to build, with time, until it eventually can cover the entire Strainer—resulting in a stoppage at the Outlet.
Sometimes a Strainer has corroded from moisture, which also can accumulate in the Tank. New Strainers are readily available for replacing damaged Strainers.
The next thing to check is the Strainer/Outlet Retaining Nut (also called a “Nipple) on the Fuel Tank Outlet (111-298-221A). If the gasoline-resistant washer is damaged or frayed, it’s time to replace the entire Retaining Nut and Outlet Tube.
From the Fuel Tank, gasoline flows through a short length of Fuel Hose into the Metal Fuel Line, which runs the length of the inside of the Tunnel. It is necessary to have a flexible Fuel Hose between the Tank and the Metal Line to absorb vibration/movement. If the Line were rigid between the Tank and the Metal Tunnel Line, it eventually would break due to vibration fatigue.
If this flexible length of Fuel Hose is frayed or just old, it is time to replace it. Cut a new length to match the old one. You want to have enough Hose there so that when the Tank is removed, it can be lifted to provide access to the Hose and its Hose Clamps. Although the gasoline at this point is solely fed through the Line by gravity, the Clamps provide security against the loosening of the Hose between the Tank and the Metal Fuel Line.
Metal Fuel Line:
Through the Tunnel, lies the Metal Fuel Line. The Metal Line is a 6 mm Outside Diameter Metal tube. It exits the rear of the Tunnel. At both the front, where the Metal Fuel Line enters the Tunnel, and at the rear, where the Metal Fuel Line exits the Tunnel, there are Rubber Grommets to buffer the metal of the Tunnel against the Metal Line. As well, the Grommets prevent the entrance of moisture and dirt into the Tunnel where these elements can damage the various components which reside inside the Tunnel. Replace the Grommets (111-209-189A) if they are missing or damaged.
Fuel Hose to the Engine Compartment:
At the nether end of the Metal Fuel Line (where it exits the Tunnel) there will be a length of Fuel Hose. This Hose runs to the Fire Wall where it connects to a Metal Fuel Line which passes through the Firewall Tin and into the Engine Compartment. Again, the consideration is for flexibility due to vibration of the car, especially at the Engine. If the Fuel Line were rigid from the Tunnel into the Engine Compartment, it soon would weaken and rupture.
If the Flexible Fuel Hose from the Tunnel Metal Line to the Metal Line passing into the Engine Compartment is old/damaged, it’s time to replace that Hose and to secure it at both ends using Clamps.
Metal Fuel Line into the Engine Compartment:
A Metal Line passes through the Fire Wall Engine Tin. A Rubber Grommet (111-127-591) inserted into the Fire Wall Engine Tin, buffers the two metal surfaces so that the vibration of the car/engine will not cut through the Metal Fuel Line. If this Grommet is missing or damaged, it’s time to replace it with a new one.
The Metal Fuel Line which passes into the Engine Compartment is not “free-floating”. It is secured by a small Bracket (311-127-525) to the Fan Housing. It is not unusual for this Bracket to be missing altogether. I do not know if these Brackets are available in the after-market, but they can be found at salvage yards. The Bracket requires a buffering piece of rubber which surrounds the Metal Fuel Line, so that when the Bracket is secured to the Fan Housing, the Metal Bracket and Metal Fuel Line do not vibrate against one another. In the photos (below) I replaced the old, hardened Rubber Buffer by cutting a short length of Fuel Hose and slicing it lengthwise to encase the Metal Line before installing the Line into the Bracket. For illustrative purposes, I inserted only a shortened piece of Metal Fuel Line into the Bracket.
Fuel Hose In the Engine Compartment:
The Engine Compartment Metal Fuel Line ends short of the Fuel Pump. Again, at this point, a short length of Fuel Hose is inserted. The purpose is the same as at other locations—to prevent damage that would occur should the Metal Line be rigid.
The Fuel Pump is the transfer station, if you would, which pressurizes the gravity-fed gasoline to the Carburetor.
From the Outlet of the Fuel Pump to the Inlet of the Carburetor there also is a section of flexible Fuel Hose.
This completes the journey of gasoline from the Tank to the Intake and Combustion System for the Engine.
Maintaining Clean Fuel to the Combustion System:
During the 1980s, I found it necessary to install Filters into our VWs due to the advent of Ethanol which began to be added to automotive fuels. Ethanol readily combines with water. The air contains moisture. Our vintage Volkswagens do not have a Sealed Fuel System. Each time we remove the Gas Tank Cap, we allow air (i.e. moisture) to enter the Tank. Ethanol combines with this accumulated moisture and carries it through the Fuel System—right into the carburetor. IF—if we don’t install a Fuel Filter at some point. The Ethanol also causes damage to the inner core of the Fuel Hoses. Particles begin to break loose and can enter both the Fuel Pump and the Carburetor. These particles contribute to plugging the flow of Gasoline through both the Pump and the Carburetor. As well, moisture in the Tank and Metal Lines results in oxidation—if you’ve ever opened a Carburetor, you probably have seen the resultant fine, red sediment.
As you know, 1967beetle.com advocates the installation of a Fuel Filtering Device either at the outlet of the Gas Tank or at the rear of the car before the Fuel Line enters the Engine Compartment. Once installed, the Fuel Filter must be monitored regularly– especially if your Gas Tank has not been recently cleaned. Create a Maintenance Schedule Sheet that includes the Monitoring of the Fuel Filter.
Understanding the Fuel System of your Beetle will help you to diagnose future problems. When you have what appears to be a fuel problem…mentally trace the System rather than to play a guessing game. Knowledge is power—use it wisely!
I want to thank David Brown of Pennsylvania for supplying missing VW Part Numbers. We are fortunate to have Volkswagen Trained individuals like David who are willing to spend time working with us to enlarge our understanding of our Vintage ’67 Beetles! David has a 1967 Standard-Standard Beetle–which I keep encouraging him to restore. Maybe we will say something in the future about what is a “Standard-Standard” Beetle.
Neva Salser contributed to this Article through her photographic skills. Thank you, Neva!
As always Jay excellent text and photos! Great job Neva! Another reference keeper!
Hello, Dick…Thanks for the comments. I especially like to have the VW Part Numbers–it certainly helps when ordering parts and one doesn’t know what to call the “thingy”! LOL May you, Carolyn and Arron have a great Christmas! jay
The clarity of your prose is a pleasure to read. It is poetry. Punctuation used in a manner for which it was invented, outstanding.
Hello, Hank…You are generous with your praise. I thank you. I do work hard at making things understandable. It comes from being a buyer in years past and from my contracting business
of almost 30 years. It sure hurts to buy the wrong product and have to eat the loss! Ouch!
Hank–you and yours have a wonderful Christmas Season. jay
I want to say a word about the Editor of 1967beetle.com–Eric Shoemaker receives my copy, then works miracles with it. I never cease to be amazed by how he highlights, separates, poses the illustrations and gets these articles into the hands of his Readers! Eric and Amanda Shoemaker put a lot of money, blood, sweat and maybe even tears into the ’67 Volkswagen Community. The results are truly splendid. Thank you, Eric and Amanda! (PS–Eric also cracks the whip once in a while–hahahahaha!) jay
Thanks.. It’s all you. I simply digest the content and display it the way (I think) a reader would want to see it. You’re a poet; a huge asset in my life… and I think a lot of ’67 owners around the world feel the same.
I loved the little poke at our current tendency to run to the forums when confronted with a problem. Seems we have forgotten how to investigate, formulate, implement and review, as part of problem solving. Now we immediately bleat out for help.
Yikes…Was it THAT evident? LOL I think that we need to put aside out timidity about these cars and
investigate. Investigating implies knowing/learning how something works. As I said, knowledge is power. When we first had VWs, I took one for a tune-up. It ran no better when I got it home. I discovered that the mechanic had not gapped the plugs–at all. I did that by finding the correct gap number and correcting things. The car ran well. Next time I saw the mechanic, I mentioned that little tidbit to him and he just shrugged his shoulders. I thought to myself–“Jay–you are an idiot! You can read!” So, I began to self-educate. Believe it or not but this is true–I used to go to the wrecking yards on the weekends. I needed parts for our every-present stable of VWs. As a part of my “continuing education”, I would remove a part, studying the process–then replace it just as it came off! The guys at the yard didn’t care. I was buying their parts. I learned a lot of things that way. I’m not ashamed to admit it! jay
In my humble opinion it all starts with a dash of curiosity and a sprinkle of ambition. So many don’t have that. One day consideration should be given to publishing a compilation of your articles. Keep up this good work. I truly enjoy the periodic postings.
Jay, Eric. Thanks for the writeup. Excellent. I also have had my share of fuel system issues, some of which you have identified. I have had a leaking gasket in the cap for the tank, loose screws holding the fuel sender on, and more recently, the bottom of my tank rusted out around the spigot, requiring a full tank replacement along with spigot and screen. I had noticed a fuel smell in the car, and these steps eliminated that. I also then noticed the grommets for the fuel line were missing, and no clamps on the fuel line. So those were replaced. Finally, I also had a leaking throttle shaft in the carb, requiring a rebuilt/rebushed carb installation. Gas was actually dripping off the shaft into the hot engine. I thought I had resolved that, and while I now have no dripping, there is still signs of gas at the throttle shaft. Further investigation determined that the fuel pump pressure (an aftermarket Brazilian model, not repairable) was over pressure. So what happens when I shut the engine off, after a minute or so, the residual pressure in the pump pushes gas past the needle and seat in the carb, causing fuel to drip from the main discharge tube on to the throttle, then eventually on to the throttle shaft where a bit gets by the bushing. So now in the process of installing a new fuel pump. I thought all this gave me a complete perspective on the fuel system, and now in reading your article I notice I do not have the fuel line clamp on the side of the fan housing. So my next job after the pump is to manufacture and install one of those. So thanks for pointing that out. Finally, in doing all this, I realized the ignition line to the coil, which then branches to the choke, fuel cutoff valve and backup lights is not fused. So a short circuit and dripping fuel seemed to spell potential disaster, so I now have a fused line going into the engine. This has been lots of fun and a learning excercise as well!
Hello, Dave…I have not heard from you in some time. I am so glad that you bring up many other issues which we should be observing while we have “custody” of these fine Volkswagens! BTW–I have Part II in process, so I will touch on some of the things which you bring up. While our son was in college, he took a job which required his taking calls from customers who needed technical help. The first thing our son did was to explain that he had a series of questions to ask which would help him to pin-point the problem His first question: Can you see that the computer power cord is properly plugged into the wall socket? He told me that some customers took exception to this seemingly prying question–but, he added–you’d be surprised at how many people found that, indeed, their computers were NOT properly connected to a power source. We, with our vintage VWs can ask ourselves these same types of questions–just begin at the beginning and follow the path. Have a great Christmas with your Family, Dave! jay
Thanks for your note Jay, and yes, I should post my experiences a bit more. My first car was a ’67 that I bought in ’69. As a 40 plus year veteran of the IT business, I really enjoyed your son’s experiences and empathize fully with him. I do have one question, does the fuel line in the engine compartment also snap into the little clip that holds the spark plug wires? I can’t recall from my original car,a and my current setup doesn’t look right. I do have a 3 way clip which I think is for that on the fan shroud. Also, a very Merry Christmas to you, Neva and the family! Dave.
Dave…Here is some information on the routing of the Engine Compartment Metal Fuel Line. This comes from David Brown of Pennsylvania: David says…” Thru 1970, the fasteners holding the Fuel Line Bracket/ Fan Housing ( as well as the right side an Housing ) are originally Slotted Screws. With the ’71 Dual Port Engine they changed to 10mm Wrench Bolts as a screwdriver no longer fits easily behind the Manifold ends. The Fuel Line also was changed to eliminate the Metal Clip (what I, Jay. call a Bracket) and now attaches to the 3 place Plug Wire Holder on the left side. Note that this 3 place Holder has 2 places for Plug Wires and a smaller space for the Fuel Line. Installing the Holder upside down causes the Plastic clip to cut the Plug Wire Insulation and the Fuel Line doesn’t clip into the larger Place because it’s smaller in diameter that the Plug Wire. Note that the 71-74 Fuel Line is reshaped and a slightly different length than the 66-70 Line to accommodate this change.” David’s comments answer several things–take a minute to digest.
My illustration has an incorrect fastener for the Fuel Line Bracket–it should be a Slotted Screw! jay
Hello, Amanda! It’s good to hear from you! I know that you stay busy with the family as well as the 1967beetle.com and LaneRussell Sites. A personal thank you for all that you do to keep these two valuable Sites running at their optimum! Give the Twins a squeeze for Neva and me, please! jay
I too would like to thank everybody for their help and could use some more. I have done my homework by the way.
My problem is that I had to replace my fuel sending unit and it’s leaked ever since. At first I thought it was the seal and I tried 2 more of each, the cork and the rubber but with no luck. As it turns out, the leak is coming from the center of the sending unit. (In you picture above, about where the red speck is). When you fill the tank past 2/3 full it spills out.
I’ve tried 3 different sending units all of which leak. I talked with a shop in Phoenix (didn’t have my car but always stop in when there) and also had my car at a local shop here and nobody can explain.
I do know the old one had a rubber cone in that area but none of the new ones do.
Anybody have any ideas?
Hello, Rick…Since I cannot see any of the Sender Units which you mention, I am going to throw out this idea. When I was putting my car together, I went through the original German Senders and found them all to have a cracked Rubber Boot at the critical point–where the Arm protrudes through the Sender Body. At that point, the Arm swings back and forth–according to the level of gas in the Tank. The Rubber Boot affixes to seal the Arm to the Sender Body at that point–to keep gasoline from seeping up around the Arm. I looked at some other Senders and found one which uses a tiny O-ring on the bottom-side of the Sender body where the Float Rod goes into the Sender Body (the old O-ring was either gone or no good–can’t recall presently). I bought a tiny O-ring at a plumbing supply and “carved” on it until it fit the space where the Float Rod enters the Body. That did the trick and after years of use, I have no leakage. Go through your Senders to see if that could be the case. There are Parts Houses which sell every size of O-ring imaginable. I do not understand why manufacturers seem to be unable to produce parts which operate properly. Let us know what you learn here. And–hopefully, someone will comment to give us a solution–anyone?
David Brown of Pennsylvania adds a relevant comment about the Gas Tank Vapor Hose. As you recall I say that the Hose is also marketed as Vacuum Hose. This is because, as David says: “The Loop in the Fuel Tank Vent Line (I, Jay, call this the Vapor Hose) acts as a Vapor/liquid separator, same as the loop in the Distributor Vacuum Line.” Thanks for this comment, David. jay
Jay, once again a spectacular article! Your article brought back vivid childhood memories when in the late seventies (I was 11 years old) we had a 74′ Sunbug. My dad, God rest his soul, was more into function than maintenance and at one point the bug “wreaked” so bad of gas fumes my sister, mother and I often become ill on longer trips. In addition, my parents were both chainsmokers!! What could go wrong?
Fortunately I’m here to tell about it! Lol
Thanks again for his splendid article….
Oh, wow! Gavin! Sigh…Memories–not always such happy ones from our VW days. Those, we try to forget, don’t we. The later Beetles had more gasoline vapor resolution equipment–which could go wrong! And..did go wrong, obviously from your report and from I have heard time and time again. Gavin–did you participate in the Hagerty Customer Appreciation Day free gas fill-up in Traverse City, MI? I saw the story about that and immediately thought of you. You and Mary and Family have a wonderful Christmas! jay
Thank you once again for outstanding work. Have you ever replaced the fuel line down through the tunnel? My ’67 sat for 37 years and it needs replacing. The entire fuel system needs replacing. Just wondering what pitfalls I can expect with regards to attaching a new line where the old one used to be. Thank you in advance for any feedback you might have
Hello, Frank! No, I never have had to replace the tunnel fuel line. Replacement usually is done on the bottom of the car, routing the metal line along the safest places. But…do you think that it is possible, using compressed air, to blow through the original line to clear any blockages? I did that with a ’65 Bug which I once owned. It blew all sorts of junk out the other end. You might try that, first. If all fails–then install a line along the bottom of the car. I will check with my trusted VW mechanic to see if he has any suggestions about replacing the line in the tunnel. I have your contact information. jay
Hello, again, Frank. I talked to an expert who told me that aside from cutting holes in the tunnel to route a fuel line, it’s next to impossible to run a new metal line through the tunnel. Getting it into the tunnel isn’t the problem–it where the metal line must exit the tunnel–where it makes a bend. He installs the replacement metal line using the body-to-chassis bolts as the tie-down points. You can get or make tabs to bolt on at those points from front to back. A bit circuitous but it works. I reckon that there are lots of VWs out there with this adaptation. But–again–I’d try blowing through the old line using compressed air to see if anything gives. Let us know what you discover, Frank! jay
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