Mechanical Fuel Injector Service

Service and rebuild the Rochester mechanical fuel injection system on a 1966 Corvette 327ci V8, including cleaning, adjustment, and testing of all injection components.

Warnings

Tools required

Parts

• Fuel injection rebuild kit (Rochester) × 1 — Use OEM specification for 1966 Rochester FI
• Fuel injector nozzles (set of 8) × 1 — Rochester part
• Fuel filter element × 1 — Rochester inline filter
• Fuel pressure regulator diaphragm × 1 — Rochester FI regulator kit
• Fuel meter body gaskets × 1 — Included in rebuild kit
• Throttle body gasket × 1 — Rochester FI throttle body
• Fuel line O-rings × 1 — Various sizes per application

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Allow engine to cool completely if recently operated
4. Place drip pans under fuel injection system components
5. Relieve fuel system pressure by loosening fuel inlet line at fuel meter body slowly
6. Have fire extinguisher positioned nearby
7. Remove air cleaner assembly and intake plenum to access fuel injection components
8. Label all fuel lines, vacuum lines, and electrical connections with tags for reassembly reference
9. Take photographs of component positions before disassembly

Procedure

1. 1

   Remove fuel lines and disconnect system
   Using fuel line wrenches, disconnect the main fuel supply line from the fuel meter body inlet. Disconnect the fuel return line from the pressure regulator. Disconnect the 8 individual fuel injector lines from each nozzle at the intake manifold, working from front to back. Cap all open fuel lines immediately with clean plugs to prevent contamination.
2. 2

   Remove fuel injector nozzles
   Remove the 8 fuel injector nozzles from the intake manifold ram tubes using appropriate wrench. Each nozzle has a banjo fitting that connects the fuel line. Keep nozzles organized by cylinder number for inspection. Inspect nozzle sealing washers and replace if compressed or damaged.
3. 3

   Remove throttle body assembly
   Disconnect throttle linkage and return springs from throttle body. Disconnect vacuum lines from throttle body ports (label each connection). Remove the 4 throttle body mounting bolts and carefully lift throttle body away from fuel meter body. Remove and discard old throttle body gasket.
4. 4

   Remove fuel meter body
   Disconnect fuel pressure regulator vacuum line. Remove the fuel meter body mounting bolts (typically 6 bolts securing unit to intake manifold). Carefully lift fuel meter body straight up to avoid damaging internal passages. Remove and discard all gaskets.
5. 5

   Clean and inspect fuel injector nozzles
   Examine each nozzle for carbon buildup, varnish deposits, or physical damage. Clean nozzles using fuel injection cleaning solvent or ultrasonic cleaner. Inspect nozzle spray patterns by back-flushing with compressed air (never blow through nozzle tip directly). Replace any nozzles with plugged orifices or damaged tips. Test nozzle opening pressure on test stand if available; specification is 120-150 psi.
6. 6

   Service fuel pressure regulator
   Remove the 4 screws securing fuel pressure regulator cover. Inspect diaphragm for cracks, holes, or stiffness. Replace diaphragm if any defects found. Clean regulator body with solvent and compressed air. Inspect regulator spring for corrosion or deformation. Reassemble regulator with new diaphragm and gasket from rebuild kit.
7. 7

   Clean fuel meter body exterior and passages
   Using appropriate solvent and soft brushes, clean all external surfaces of fuel meter body. Blow out all fuel passages with compressed air, working from inlet to outlet. Clean fuel filter screen inside inlet fitting. Do not disassemble internal metering valve unless experienced with Rochester FI calibration. Inspect all mounting surfaces for warping or damage.
8. 8

   Replace fuel filter element
   Locate inline fuel filter in fuel supply line (typically near fuel meter body). Disconnect fuel lines using fuel line wrenches. Remove old filter element and inspect for contamination level. Install new fuel filter with arrow pointing toward fuel meter body (direction of flow). Reconnect fuel lines with new O-rings if applicable.
9. 9

   Clean throttle body
   Remove throttle plates if heavy carbon buildup exists by removing the 2 screws per plate. Clean throttle bore, plates, and shafts with throttle body cleaner. Inspect throttle shaft bushings for wear or play. Clean idle air bleeds and passages. If throttle plates were removed, reinstall with new screws and stake lightly to prevent loosening.
10. 10

    Reinstall fuel meter body
    Install new fuel meter body gasket on intake manifold surface. Carefully position fuel meter body, ensuring alignment with mounting holes. Install mounting bolts finger-tight, then torque in crossing pattern to ensure even seating. Reconnect vacuum line to fuel pressure regulator.
11. 11

    Reinstall throttle body
    Install new throttle body gasket on fuel meter body mounting surface. Position throttle body and install 4 mounting bolts, torquing in crossing pattern. Reconnect all vacuum lines according to labels and photographs. Reconnect throttle linkage and adjust for smooth operation with slight freeplay. Install throttle return springs.
12. 12

    Install fuel injector nozzles
    Install new sealing washers on each injector nozzle banjo fitting. Install nozzles into intake manifold ram tubes in correct cylinder order. Tighten nozzles securely but do not overtighten. Reconnect individual fuel lines from fuel meter body distribution block to each nozzle, working systematically from front to back.
13. 13

    Reconnect main fuel lines
    Reconnect main fuel supply line to fuel meter body inlet using fuel line wrench. Install new O-ring if applicable. Reconnect fuel return line from pressure regulator to fuel tank return. Ensure all connections are tight and properly seated.
14. 14

    Initial fuel system pressurization and leak check
    Reconnect negative battery cable. Turn ignition key to ON position (do not start engine) to activate fuel pump. Observe all fuel connections, injector nozzles, and fuel meter body for any fuel leaks. Cycle ignition 3-4 times to build full system pressure. Repair any leaks before proceeding.
15. 15

    Start engine and perform initial adjustments
    Start engine and allow to warm to operating temperature. Check for smooth idle and proper throttle response. Adjust idle mixture screws on fuel meter body for highest manifold vacuum and smoothest idle (typically 1.5-2 turns out from lightly seated). Set idle speed to 750-800 rpm using throttle stop screw. Check fuel pressure at test port: should read 15-18 psi at idle.

Reassembly

1. Reinstall intake plenum and air cleaner assembly after all adjustments are complete
2. Double-check all fuel line connections for tightness
3. Verify all vacuum lines are properly connected and secured
4. Ensure throttle linkage operates smoothly through full range without binding

Verification

• Engine should idle smoothly between 750-800 rpm when fully warmed
• Fuel pressure should read 15-18 psi at idle with engine running
• No fuel leaks should be present at any connection points
• Throttle response should be crisp with no hesitation or stumbling
• Engine should accelerate smoothly through full RPM range
• Manifold vacuum at idle should be steady at 18-21 inches Hg
• All injector nozzles should spray evenly (listen for smooth operation)
• Test drive vehicle to verify proper performance under load

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