Another fantastic and well articulated article from Jay Salser. Our timing lights are pointed in your direction. Thank you for all you do here at 1967beetle.com.
I commonly hear the words—“I had a vapor lock!”
We mostly think of vapor in conjunction with heat. So a BIG question arises when the “vapor lock” occurs under cool circumstances. This renders such a diagnosis suspect.
It is very easy to blame a poorly functioning air-cooled engine on a “vapor lock”. When someone calls to ask what can be done to cure a “vapor lock”, I ask lots of questions.
I want to hear how the car-engine acted. I want to hear about the circumstances that led to the problem. I want to hear about the ambient temperature.
My mind follows the Fuel System from the Tank to the Fuel Pump. And I literally ask the caller questions during my mental perusing of the Fuel System. It’s like a movie playing through my brain as I listen and ask questions.
In any case usually no firm diagnosis is reached and the next time it happens, the same scenario plays out.
One person reported that his car stalled at the roadside. A passing motorist stopped to give aid. He produced a bottle of water and poured it over the Fuel Pump. Soon, the engine started and the driver resumed his journey homeward. The assumption—the Fuel Pump had suffered a “vapor lock”—even though the weather wasn’t even hot.
Recently, Frank Salvitti talked to me about the “vapor lock” which temporarily put his car out of commission. He had driven a few miles, parked his Beetle and gone into the store to make his purchases. When he came out—the car would not start. He said that he could not see any fuel in the Fuel Filter (mounted, still, in the engine compartment). Eventually, after the engine had cooled, he surmised, the car started and he drove home.
Here’s what I asked Frank to do. I asked him to get a Fuel Pressure Gauge to connect between the Fuel Pump and the Carburetor. In a few days, he reported Fuel Pressure in excess of 5 PSI. This is far too much pressure.
The Float Valve (commonly called the Needle Valve) in the top of the Carburetor cannot withstand such High Pressure. Gasoline forces its way into the Bowl and begins to overflow down the throat of the Carburetor. When this happens, not enough air can mix with the un-atomized gasoline and the engine is choking to death on raw fuel. It either stalls or won’t restart after having been turned off.
Until all of that raw gas has dispersed and evaporated.
Think of the Bowl of the Carburetor as a toilet tank. If we hold the float down, water continues to fill the tank until it finally overflows. We have generated “excessive pressure” on the tank float—overpowering the cut-off mechanism.
Sometimes the Pressure is so great that gasoline can be seen percolating in the filter (if it is connected between the Pump and the Carb). With the Air Breather removed, raw gas sometimes can be seen over-flowing down the throat of the Carburetor. This especially can be seen if the car has been parked nose-uphill.
First, let’s review how the Fuel Pump operates through the following photographs.
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.
Not a week goes by here at 1967beetle.com without someone sending photos of their vintage pride and joy, fresh from bodywork and paint. More times than not, their car has an aftermarket front fender. If you didn’t know, the ’67 Beetle front fenders (German) are another one of those fantastic one year only items. If you look at the vintage market, you’ll see plenty of folks claiming, “high end restoration.” However, (sadly) people often use cheap parts for max profit. The power is being able to tell the difference. I’d like to explain how can you tell if you’re dealing with genuine German VW metal. Let’s discuss below, with photos to help illustrate how simple the difference really is. I’d love to know how many readers actually go outside and look at their cars after reading this.
Turn signal holes This is by far one of the easiest ways to distinguish the real deal from aftermarket. On the right we have a genuine German VW fender. If you remove your top turn signal assembly, the hole punched should be round. On the top of the hole, if you looked close enough you’d also see that the fender is stamped with a VW logo mark. Over time, these are often worn away. However, they are there from the factory. Also, the metal of German fenders is much thicker. On the left, we have an aftermarket fender with a goofy oblong hole. Why the folks making these did not use proper tooling to produce something that matches an OE fender is beyond me.
Gasoline is a wonderful “invention” but one which we should respect because of its evaporative and, thus, flammable qualities. We must use great care when working with gasoline. My number one rule is to work with gasoline outdoors so that gas vapors cannot accumulate
I frequently am asked by fellow Volkswagen enthusiasts what to do about gasoline spillage. This is a valid concern. When changing the fuel hoses, there always is the possibility for some gasoline to be spilled.
THERE IS A BETTER WAY!
While talking with my good 1967 Beetle friend, Frank Salvitti, of Long Island, New York, this past weekend, the subject of fuel spillage came up.
Says Frank—“Oh…that’s no problem! I use Line Clamp Pliers.” Now, Frank is a seasoned mechanic and knows things that a lot of us DIY-ers don’t. I asked Frank to explain his process and he told me that he would send some photos to illustrate his tool of choice.
Over the years, I have seen screws inserted into the ends of hoses, pieces of whittled wood, and other variations, in order to avoid the loss of gasoline while the person is working to change fuel hoses. But it takes time to insert something into the hose. In the meantime, the gasoline is draining. I laugh now, but I recall the many times I was beneath a VW, working on a fuel hose, and had the fuel to drain right onto my face or clothing. Not much way to avoid it if you are working with the fuel hose over head!
Frank emphasized the simplicity of the Line Clamp Tool and how to use it. The beauty is that if anything at all spills, it will be a couple of drops which remain at the end of the hose after it has been clamped. A paper towel can be placed there when the hose is disconnected and will take care of such a small amount.
The Clamp is applied appropriately—THEN—the fuel hose is disconnected.