Chrysler Full-Size Trucks 1967-1988 Repair Guide

Mechanical Fuel Pump

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REMOVAL & INSTALLATION



See Figures 1 through 7


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the fuel lines from the inlet and outlet sides of the fuel pump.
  4.  



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Fig. Fig. 1: Disconnect the fuel lines at the pump assembly

  1. Plug these lines to prevent gasoline from leaking out.
  2.  
  3. Unscrew the retaining bolts from the fuel pump and remove the fuel pump from the engine.
  4.  



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Fig. Fig. 2: After you have unthreaded the mounting bolts, remove the pump from the engine

  1. Remove the old gasket from the engine and/or fuel pump.
  2.  
  3. Clean all mounting surfaces.
  4.  
  5. Using a new gasket, install the fuel pump in the reverse of the removal procedure.
  6.  



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Fig. Fig. 3: Before installation, cleaning all traces of the old gasket, then position a new one on the pump

TESTING



See Figures 4, 5, 6, and 7

Pressure Test

See Figure 8

Before proceeding with this test, verify there is no leakage. If leakage is found, repair or replace components as necessary.

If leakage is not apparent, the following pressure test should be performed.

  1. Insert a "T'' fitting into the fuel line at the carburetor.
  2.  



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Fig. Fig. 4: Mounting for a 5-225 engine fuel pump

  1. Connect a 5 in. (152mm) piece of hose between the "Tee'' fitting and a pressure gauge.
  2.  



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Fig. Fig. 5: Mounting for a V8-318/360 engines



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Fig. Fig. 6: Mounting for a V8-361/413 engines



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Fig. Fig. 7: Mounting for a V8-400/440 engines

  1. Drain the fuel line leading to the carburetor in order to allow the pump to operate at maximum capacity.
  2.  
  3. Connect a tachometer and start the engine. Allow the engine to run at idle speed. The fuel pump pressure should be 5.5-5.0 psi (24-34 kPa) for 5-cylinder engines or 4.0-7.0 psi (34-48 kPa) for V8 engines. When the engine is stopped, the pressure should return to zero very slowly. If it rapidly or instantly drops to zero, a leaky outlet valve is indicated.
  4.  

Volume Test
  1. Disconnect the fuel line from the carburetor. Place the end of the line in a container holding at least 1 quart.
  2.  



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Fig. Fig. 8: Pressure testing the fuel pump

  1. The fuel pump output should be 1 quart in 1 minute or less at 400 rpm.
  2.  
  3. If the pump doesn't operate as specified, replace the fuel filter and check for a pinched and/or blocked fuel line. If the pump output is still insufficient, replace the pump.
  4.  

 
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