Volkswagen Air-Cooled 1970-1981 Repair Guide

Mechanical Fuel Pump

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All 1970-74 Type 1 and 2 models utilize a mechanical fuel pump. The pump is located to the left of the generator/alternator on Type 1 and 2/1600 models, and located next to the flywheel on dual carburetor Type 2 models. On Type 1 and 2/1600 models the pump is pushrod operated by an eccentric on the distributor driveshaft. On Type 2/1700 and 2/1800 twin carb models, the pump is operated by a pushrod which rides on a camshaft eccentric.

REMOVAL & INSTALLATION Types 1 and 2/1600



See Figures 1, 2 and 3

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Fig. Fig. 1: To remove the mechanical fuel pump on upright engines, disconnect and plug the fuel lines ...



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Fig. Fig. 2: ... then remove the two fuel pump attaching bolts



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Fig. Fig. 3: Lift the fuel pump off of the engine case-make sure to remove the old gasket from the engine

See Figure 4

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Fig. Fig. 4: Exploded view of the fuel pump used on 1970 Type 1 models

  1. Disconnect the fuel lines at the pump and plug them to prevent leakage.
  2.  
  3. Remove the two securing nuts.
  4.  
  5. Remove the fuel pump. If necessary, the pushrod, gaskets, and intermediate flange may also be removed.
  6.  
  7. When installing the fuel pump, it is necessary to check the fuel pump pushrod stroke. This is done by measuring the distance that the pushrod projects above the intermediate flange when both gaskets are in place. The rod must project 1 / 2 inch. If not, remove or insert enough bottom gaskets under the flange until it does.
  8.  
  9. Fill the cavity in the lower part of the fuel pump housing with grease. Total pushrod length is 4.252 in. for all Type 2/1600 and for Type 1 models equipped with generators. Pushrod length is 3.937 in. for all 1973-74 Type 1 models equipped with alternators. Replace any worn pushrod.
  10.  
  11. Using new gaskets, install the fuel pump and tighten the two securing nuts.
  12.  
  13. Install the fuel hoses.
  14.  

Types 2/1700 and 2/1800 With Twin Carburetors See Figure 5

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Fig. Fig. 5: Exploded view of the fuel pump used on 1972-74 Type 2 models equipped with the twin carburetor system

  1. Remove the engine.
  2.  
  3. Once the engine is removed, remove the upper and lower deflector plates and the carburetor preheater connection to gain access to the pump mounting bolts (adjacent to the flywheel).
  4.  
  5. Disconnect and plug the fuel lines to the carburetors.
  6.  
  7. Remove the two retaining bolts and lift off the fuel pump, gaskets and intermediate flange.
  8.  
  9. Reverse the above procedure to install, using new gaskets. Remember to coat the pushrod and lever with grease.
  10.  

Prior to installation of the fuel pump, check the action of the camshaft eccentric driven pushrod. Install just the intermediate flange on the engine with 2 gaskets underneath and one on top. Turn the engine over by hand until the pushrod is on the highest point of the camshaft eccentric. Then, measure the distance between the tip of the pushrod and the top gasket surface. Adjust, as necessary, to 0.2 in. by removing or installing gaskets under the intermediate flange. Total pushrod length should be 5.492 in. minimum. Replace, if worn.

TESTING & ADJUSTING



The maximum fuel pump pressure developed by the Type 1 and 2/1600 fuel pump is 3-5 psi at 3,400 rpm for the Type 1 (4,000 rpm for the Type 2). The maximum fuel pump pressure developed by the Type 2 Twin carb fuel pump is 5 psi at 3,800 rpm.

All fuel pumps deliver 400 cc of fuel per minute at 3,800-4,000 rpm.

The only adjustment possible is performed by varying the thickness of the fuel pump flange gaskets. Varying the thickness of the gaskets will change the stroke of the fuel pump pushrod. This adjustment is not meant to compensate for a pump in bad condition; therefore, do not attempt to vary the height of the pushrod to any great extent.

The fuel pumps used on 1970 Type 1 and 2 models, and 1972-74 Type 2 models may be disassembled for cleaning or repairs. All other mechanical pumps are permanently sealed and must be replaced if found defective.

 
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