Mechanical Fuel Injection Pump Removal and Installation

This procedure covers the removal and installation of the Rochester mechanical fuel injection pump on a 1966 Chevrolet Corvette 327ci V8, including disconnection of fuel lines, linkage, and timing components.

Warnings

Tools required

Parts

• Fuel injection pump mounting gasket × 1 — Use OEM specification
• Fuel line O-rings (complete set) × 1 — Rochester fuel injection service kit
• Throttle linkage bushings × 1 — Use OEM specification
• Fuel filter (recommended replacement) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Disconnect negative battery cable to prevent accidental fuel pump activation and electrical shorts.
3. Allow engine to cool completely if recently operated (minimum 2 hours).
4. Position Class B fire extinguisher within immediate reach of work area.
5. Ensure adequate ventilation in work area - open garage doors or work outdoors.
6. Gather all documentation: take comprehensive photographs of all fuel lines, vacuum lines, throttle linkage, and electrical connections from multiple angles before any disassembly.
7. Prepare labeling system using wire tags or masking tape and permanent marker.
8. Place large drain pan beneath fuel injection pump area to catch fuel spillage.
9. Have at least 10 shop rags ready for fuel absorption.

Procedure

1. 1

   Relieve fuel system pressure
   Start engine and allow it to run until the fuel tank is nearly empty or disconnect the fuel pump feed line at the tank and run the engine until it dies from fuel starvation. Crank engine for 5 seconds after it stalls to clear remaining pressure. Verify pressure is relieved by carefully loosening one fuel line connection at the pump (not removing) and checking for fuel spray. Retighten connection.
2. 2

   Remove air cleaner and throttle linkage
   Remove the air cleaner assembly by disconnecting the wing nut and lifting off the assembly. Carefully disconnect the throttle linkage from the throttle shaft on the fuel meter assembly. This includes the throttle rod from the accelerator pedal, kickdown linkage (if automatic transmission), and return spring. Label each connection point with wire tags indicating orientation and connection sequence.
3. 3

   Disconnect electrical connections
   Disconnect all electrical connections to the fuel injection system. This includes the cold start solenoid wire, fuel pump safety switch (if equipped), and any temperature sensor wiring at the manifold. Label each connector with its corresponding component location.
4. 4

   Disconnect fuel lines from injection pump
   Using line wrenches to prevent rounding, carefully disconnect all fuel lines from the injection pump. These include the high-pressure fuel supply line from the tank, the fuel return line, and the 8 individual fuel distribution lines to each cylinder nozzle. Label each nozzle line with its corresponding cylinder number (1-8). Cap or plug all open lines immediately to prevent contamination. Allow residual fuel to drain into the catch pan.
5. 5

   Remove fuel distribution nozzles and lines
   Working systematically from cylinder 1 through 8, use a line wrench to disconnect each fuel nozzle line at the cylinder head. Remove the fuel distribution lines as an assembly if possible to preserve routing and minimize chance of cross-connection. The nozzles themselves can remain in the cylinder head unless service is required.
6. 6

   Disconnect vacuum and breather lines
   Disconnect all vacuum lines connected to the fuel meter body, including manifold vacuum reference line, distributor advance line (if routed through meter), and any crankcase breather connections. Label each line with origin and destination.
7. 7

   Mark injection pump timing position
   Before removing the pump, establish the current timing relationship. Mark the pump body position relative to the mounting flange with a scribe or paint pen. Note the position of any timing marks on the pump drive coupling. If the pump drive has offset drive dogs, mark the orientation carefully. This reference is critical for initial reassembly timing.
8. 8

   Remove injection pump mounting hardware
   Remove the 2 bolts securing the fuel injection pump to the timing cover mounting pad. These are typically 9/16" hex head bolts. Support the pump body with one hand while removing the second bolt to prevent the pump from dropping.
9. 9

   Remove fuel injection pump assembly
   Carefully pull the fuel injection pump straight away from the engine. The pump is driven by a gear that meshes with the camshaft gear inside the timing cover. Pull steadily but gently to disengage the drive coupling. Once free, immediately cover the timing cover opening with a clean shop rag to prevent debris entry. Place the removed pump on clean shop rags away from the work area.
10. 10

    Inspect drive gear and coupling
    With the pump removed, inspect the exposed drive gear and coupling at the timing cover for wear, damage, or metal contamination. Check teeth for chipping, scoring, or unusual wear patterns. Rotate the drive gear by hand (with ignition disabled) to verify smooth operation. Any binding or rough spots indicate internal timing gear damage requiring further investigation.
11. 11

    Clean mounting surfaces
    Remove the old gasket material from both the pump mounting flange and the timing cover mounting pad using a gasket scraper. Be extremely careful not to allow any debris to fall into the timing cover opening. Keep the opening covered except when actively cleaning the immediate mating surface. Clean both surfaces with solvent and wipe dry with lint-free shop rags.
12. 12

    Prepare replacement or serviced pump
    If installing a replacement or rebuilt pump, verify the drive coupling orientation matches your timing marks from removal. Pre-lubricate the drive gear teeth with clean engine oil. Install new O-rings on all fuel line ports on the pump body, lubricating them lightly with clean gasoline or fuel system assembly lubricant.
13. 13

    Position new mounting gasket
    Install the new fuel injection pump mounting gasket onto the timing cover mounting pad, aligning the bolt holes. The gasket may have locating pins or offset holes to ensure correct orientation. Do not use gasket sealer unless specified by the pump manufacturer.
14. 14

    Install fuel injection pump
    Align the pump drive coupling with the drive gear inside the timing cover, referencing your timing marks from disassembly. The coupling has offset engagement dogs that must align correctly. Gently rotate the pump body slightly while applying light inward pressure until the coupling engages and the pump seats fully against the gasket. The mounting bolt holes should align naturally when coupling is properly engaged.
15. 15

    Install pump mounting bolts
    Install the 2 pump mounting bolts finger-tight initially. Verify the pump is seated squarely against the timing cover. Tighten the mounting bolts in a cross pattern to draw the pump down evenly. Without specific torque specifications available, tighten to approximately 18-22 ft-lbs, using feel to achieve secure mounting without overtightening the aluminum timing cover bosses.
16. 16

    Reconnect fuel distribution lines
    Reconnect the 8 individual fuel distribution lines to the pump body in their original positions using your labels. Each line must connect to its correct cylinder to maintain proper injection sequence. Start all fittings by hand to avoid cross-threading, then tighten with line wrenches to approximately 12-15 ft-lbs. Do not overtighten as these are precision fittings.
17. 17

    Reconnect main fuel supply and return lines
    Reconnect the high-pressure fuel supply line from the tank and the fuel return line to the pump body. Ensure fittings are clean and O-rings are properly seated. Tighten with line wrenches to secure without overtightening.
18. 18

    Reconnect vacuum and breather lines
    Reconnect all vacuum and breather lines to their original locations using your labels and photographs as reference. Ensure each connection is secure and hoses are not kinked or stretched.
19. 19

    Reconnect electrical connections
    Reconnect all electrical connections including cold start solenoid, fuel pump safety switch, and any temperature sensors. Verify each connector is fully seated and locked.
20. 20

    Reinstall throttle linkage
    Reinstall the throttle linkage to the fuel meter throttle shaft in reverse order of removal. Install new bushings if originals show wear. Ensure all linkage moves freely through full throttle range without binding. Adjust return spring tension to provide positive throttle closure.
21. 21

    Reconnect battery and prime fuel system
    Reconnect the negative battery cable. Turn the ignition key to ON position (not start) to activate the fuel pump and pressurize the system. Listen for pump operation. Cycle the key on-off 3-4 times to fully prime the system. Carefully inspect all fuel line connections for leaks while system is pressurized. Wipe any fuel residue with shop rags and verify no active leaks are present.
22. 22

    Initial startup and leak check
    With fire extinguisher at hand, start the engine. It may take extended cranking (10-15 seconds) to fully prime the injection system. Once started, allow engine to idle and immediately inspect all fuel connections for leaks. Look for fuel seepage, drips, or spray at every connection point. Shut down immediately if any leaks are detected and repair before proceeding.
23. 23

    Set initial injection pump timing
    With engine at operating temperature, connect a timing light to cylinder 1. Check base ignition timing first and set to specification (typically 4-8 degrees BTDC for 1966 327, verify with emission decal). The fuel injection pump timing must be synchronized with ignition timing. Loosen the pump mounting bolts slightly and rotate the pump body to advance or retard injection timing as needed. This is a critical adjustment requiring precise coordination between fuel delivery and ignition. Refer to factory service manual for exact procedure and timing specifications for your specific Rochester fuel injection system variant.

Reassembly

1. Torque specifications are critical for this procedure but are not currently in the database. Until verified specifications are available, use careful mechanical judgment and follow industry-standard practices for aluminum timing cover components and fuel system fittings.
2. All fuel line connections must be leak-free under full system pressure before the vehicle is driven.
3. Injection pump timing is the most critical final adjustment and directly affects engine performance, emissions, and longevity.

Verification

• Perform complete fuel system leak check with engine running at idle and at 2000 RPM for 5 minutes minimum. Inspect every fuel connection with engine running and system at full pressure.
• Verify smooth idle quality with no hunting, surging, or misfiring. Rochester mechanical injection should provide very stable idle when properly timed.
• Test drive vehicle and verify smooth acceleration, no hesitation, no detonation or pinging under load, and proper high-speed operation.
• Recheck all fuel connections for leaks after test drive when system is hot and at maximum operating pressure.
• Verify throttle linkage provides full throttle opening and returns completely to closed position.
• Monitor fuel pressure with mechanical gauge if available - system pressure should be 30-50 PSI at idle, 80-100 PSI at wide open throttle depending on specific system configuration.

More procedures for this vehicle