GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Fuel Pressure Relief

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Prior to servicing any component of the fuel injection system, the fuel pressure must relieved. If fuel pressure is not relieved, serious injury could result.

TBI MODEL 300 OR 700 (2.5L ENGINE)



  1. Place the transmission selector in PARK (automatic transmissions) or NEUTRAL (manual transmissions), then set the parking brake and block the drive wheels.
  2.  
  3. Loosen the fuel filler cap to relieve tank pressure.
  4.  
  5. Either remove the FUEL PUMP fuse from the fuse block in the passenger compartment (early model vehicles) or disengage the three terminal electrical connector at the fuel tank (late model vehicles). If you are unsure which method works for your truck, try removing the fuel pump fuse. If this does not disable the pump, the electrical connectors at the fuel tank must be disengaged.
  6.  
  7. Start the engine and allow to run until it stops due to lack of fuel.
  8.  
  9. Engage the starter (turn key to start) for three seconds to dissipate all pressure in the fuel lines.
  10.  
  11. Turn the ignition OFF , then re-engage the connector at the fuel tank or install the fuel pump fuse.
  12.  
  13. Disconnect the negative battery cable to prevent accidental fuel spillage should the ignition key accidentally be turned ON with a fuel fitting disconnected.
  14.  
  15. When fuel service is finished, tighten the fuel filler cap and connect the negative battery cable.
  16.  


CAUTION
To reduce the chance of personal injury when disconnecting a fuel line, always cover the fuel line with cloth to collect escaping fuel, then place the cloth in an approved container.

TBI MODEL 220 (2.8L AND 4.3L ENGINES)



  1. Disconnect the negative battery cable.
  2.  
  3. Loosen fuel filler cap to relieve fuel tank pressure.
  4.  
  5. The internal constant bleed feature of the Model 220 TBI unit relieves fuel pump system pressure when the engine is turned OFF . Therefore, no further action is required.
  6.  

Allow the engine to set for 5-10 minutes; this will allow the orifice (in the fuel system) to bleed off the pressure.

  1. When fuel service is finished, tighten the fuel filler cap and connect the negative battery cable.
  2.  

 
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