Drive gear on camshaft, Left. Porsche 911 69-73  ›  90111002300

MFI Pump Drive Gear on Camshaft, Left

The OE Match MFI pump drive gear is a replacement component for the left-hand camshaft on Porsche 911 models manufactured between 1969 and 1973 and equipped with mechanical fuel injection (MFI).

This gear forms part of the drive system for the Bosch mechanical fuel injection pump, transferring rotational movement from the left camshaft to the injection pump through the toothed drive belt.

Correct operation of this drive system is essential for maintaining the mechanical relationship between the engine and fuel injection pump, helping ensure accurate fuel delivery and consistent engine performance.

What Does the MFI Pump Drive Gear Do?

The MFI pump drive gear is mounted on the left-hand camshaft and drives the toothed belt connected to the mechanical fuel injection pump.

As the engine rotates, the camshaft turns the drive gear, which operates the injection pump in synchronisation with the engine.

This allows the mechanical injection system to deliver fuel at the correct point in the engine's operating cycle.

Why Does It Fail?

Although designed for long service life, the drive gear can deteriorate through age, wear or damage.

Common causes include:

• Worn or damaged gear teeth
• Corrosion or surface deterioration
• Incorrect toothed belt tension or alignment
• Damage during engine or injection system repairs
• Wear or damage to the gear mounting arrangement
• Long-term mechanical stress

A damaged gear can affect the operation of the injection pump drive system and may eventually cause the toothed belt to slip or lose correct engagement.

When Should It Be Replaced?

Replacement is recommended when the original drive gear shows visible tooth wear, cracking, corrosion or mechanical damage.

The gear should also be inspected during:

Incorrect injection pump timing, irregular engine operation or damage to the MFI drive belt may indicate a problem within the drive system and should prompt further inspection.

Confirm compatibility using the original part number and engine specification before ordering.

Installation Notes

Correct installation and alignment are essential for reliable mechanical fuel injection operation.

Inspect the toothed drive belt, associated injection pump gear, mounting hardware and related components for wear or damage.

Following installation, check the drive belt tension and mechanical fuel injection pump timing according to the Porsche workshop procedure.

Porsche 911 Mechanical Fuel Injection Pump Drive Gears & MFI Components

The mechanical fuel injection system fitted to selected early Porsche 911 models relies on accurate mechanical synchronisation between the engine and Bosch injection pump.

The left-hand camshaft drive gear is an essential component of this arrangement, transmitting rotational movement through the toothed belt to operate the fuel injection pump.

Over time, wear, corrosion or damage to the drive gear can compromise the reliability of the MFI drive system.