VW Bug Carburetor Problems

Written by stephannie hibbard
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VW Bug Carburetor Problems

Because the Volkswagen Beetle engine is air-cooled, the air delivery system is vital to maintaining the proper running temperature of the car. This makes the fuel to air mixture, regulated by the carburettor, an integral part, not only to fuel efficiency and engine power, but to the overall health and performance of the engine.

Location and Function of the Carburetor

The carburettor on a standard VW Beetle engine is located almost directly in the centre of the visible part of the engine when the deck lid is opened. The main function of the carburettor is to regulate the fuel to air mixture, changing the amount of air combined with fuel as it enters the cylinders of the engine. This regulation, by changing the chemical composition of the fuel mixture in the engine, also changes the rate at which the fuel explodes (combustion) and burns, which in turn changes how much pressure is placed on the cylinders and, therefore, how fast they push outward and inward.

Carburettor Adjustments

Problems with a VW Bug carburettor are among the easiest to recognise. Any problem with the carburettor will immediately change the way the car runs. It will often also change the way the engine sounds and the way the engine exhaust looks or smells.

Often, however, the carburettor is not malfunctioning, but needs to be adjusted. Adjusting a VW carburettor is straightforward: you need either a carburettor adjustment tool, which resembles a very narrow-bladed screwdriver, or a very narrow-bladed screwdriver.

The carburettor adjustment screw is in the centre of the carburettor. Turning this screw to the right or left raises or lowers the amount of air mixed with the fuel in the engine.

Adjusting the Carburetor

Carburettor adjustments should be done with the engine running. Turn on the engine, set the parking brake, and shift the car into neutral to allow it to continue running without the clutch depressed. Open the deck lid, and turn the carburettor adjustment screw to the right or left. Due to variations in engines and wear and tear, there is no definite answer as to which direction will accomplish the needed adjustment.

While you are turning the adjustment screw very slowly, listen to the engine and observe the exhaust. The engine should run smoothly without any obvious popping sounds or uneven idling and should not sound like the accelerator is being pressed. VW Bug engines are slightly loud, so turning the screw until the engine is quieter may lower the air to fuel mixture too far. However, if your Beetle is roaring, you may need to tone the mixture down until it reaches a more reasonable noise level.

When the Carburetor is Adjusted Properly

The exhaust should be clear and you should not be able to smell gasoline or any burning smell. The presence of an identifiable fuel odour means that you have turned the mixture down too far and the fuel is not being used before it reaches the exhaust. The presence of a burning smell indicates fuel is burning too fast and you have turned the mixture up too far.

When You Need a New Carburetor

If you cannot achieve the right air to fuel balance through adjusting your carburettor or you notice the carburettor leaking anywhere, you may need to replace it. Replacement Beetle carburettors are available through speciality Beetle parts replacement houses and online. Many auto parts stores will also carry basic engine parts for Beetles such as alternators and carburettors. Be sure that your replacement carburettor is the correct one for your engine size and model year. If you are replacing a stock carburettor, check for the OEM (Original Engine Manufacture) label, which will ensure that your replacement carburettor matches as closely as possible the specs of the original.

Replacing the Carburetor

The carburettor, along with many other vital engine parts, is relatively simple to replace. You will need a set of metric wrenches--all VW Beetle parts are measured in centimetres. The process of replacing the carburettor is straightforward: remove all the connections, clean the mounting posts of any remaining seal material, place the new seals, mount the new carburettor, bolt it down and replace all the connections. Once the new carburettor is in place, start the engine and check for fuel leaks. Follow the earlier adjustment instructions to fine-tune the mixture and your Beetle is once more ready to go.

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