Volvo Penta D3 Fuel Delivery Pipe 31251173 | OEM Common Rail Cylinders 3-4

Part Information

• Part Number: 31251173
• Brand: Volvo Penta
• Official Product Type: High-Pressure Fuel Delivery Pipe — Cylinders 3 and 4
• Supersedes: 31303608
• Replaced By: No current supersession on record
• Diagram Position: Common-Rail Fuel Injection System — Delivery pipe serving cylinders 3 and 4 (D3 fuel injector / delivery pipe assembly, generations D–H)

Overview

The Volvo Penta 31251173 is a genuine OEM high-pressure fuel delivery pipe for the common-rail fuel injection system on Volvo Penta D3 marine diesel engines. It connects the distribution rail to the injectors serving cylinders 3 and 4, and supersedes the earlier reference 31303608. The D3 fuel system uses four position-specific delivery pipes — each precision-formed for a specific routing path and cylinder connection. They are not interchangeable, and high-pressure common-rail pipes must never be reshaped or modified to fit.

Compatible Applications

• Volvo Penta D3-110I (generations D–H)
• Volvo Penta D3-140A / D3-140I (generations D–H)
• Volvo Penta D3-150I (generations D–H)
• Volvo Penta D3-170A / D3-170I (generations D–H)
• Volvo Penta D3-200A / D3-200I (generations D–H)
• Volvo Penta D3-220A / D3-220I (generations D–H)

Confirm your complete engine model, generation suffix, and serial number against the Volvo Penta D3 fuel injector and delivery pipe diagram before ordering.

Serial Number Requirements

The D3 common-rail system uses several position-specific high-pressure pipes, each formed for a particular injector or pump connection. Always confirm by engine model, generation suffix, and serial number. Do not substitute delivery pipes between cylinder positions.

System

Fuel System — Common-Rail High-Pressure Fuel Injection / Distribution Rail to Injectors (Cylinders 3 & 4)

Related Parts — D3 Common-Rail Fuel System

The following components are part of the D3 fuel injection system and should be inspected during delivery pipe service:

• Delivery Pipe — 31251172 (cylinders 1 and 2)
• Delivery Pipe — 31251174 (cylinder 5 / fuel-pump circuit)
• Delivery Pipe — 31251175 (fuel-pump connection)
• Distribution Pipe — 30777759
• Pressure Sensor — 30787950
• Control Valve — 31216313
• Injector — 3801385
• Retaining Clamp — 31272772
• O-ring Kit — 31272771

Dimensions & Weight

• Weight: Approximately 0.5 kg
• Pipe routing and dimensions are specific to the cylinders 3 and 4 position — confirm via Volvo Penta D3 fuel system diagram

When This Part Needs Replacement

Replace the delivery pipe if any of the following apply:

• Pipe is bent, kinked, or physically damaged
• Corrosion or external damage to the pipe body or fittings
• Leaking at a high-pressure connection (rail or injector end)
• Damaged during injector or fuel rail service
• Unable to seal correctly at the fitting after reassembly

High-pressure common-rail pipes must not be reshaped, bent, or modified to fit. If the pipe is damaged, replace it with the correct OEM part.

Installation Notes

Use the applicable Volvo Penta D3 service procedure for all high-pressure fuel system work. Tighten all fuel connections to the specified torque values — over- or under-tightening high-pressure fittings can cause leaks or fitting damage. Inspect the injector and rail fittings for damage before installing the new pipe. Replace the O-ring kit (31272771) at the same time if fittings have been disturbed.

Technical FAQ

Q: What superseded part number does 31251173 replace?
A: 31251173 supersedes the earlier Volvo Penta reference 31303608. Always order by the current active OEM number to ensure you receive the updated pipe.

Q: What is the difference between 31251172, 31251173, 31251174, and 31251175?
A: These are four separate position-specific high-pressure delivery pipes in the D3 common-rail fuel system. 31251172 serves cylinders 1 and 2, 31251173 serves cylinders 3 and 4, 31251174 serves cylinder 5 and the fuel-pump circuit, and 31251175 is the fuel-pump connection pipe. They are not interchangeable.

Q: Can I reshape a delivery pipe to make it fit?
A: No. High-pressure common-rail fuel pipes must never be bent or reshaped. The pipe geometry is precision-formed for the specific routing path and connection angles. A modified pipe can fail under operating pressure.

Q: How do I confirm this is the right pipe for my engine?
A: Confirm your engine model, generation suffix (D, E, F, G, or H), and serial number, then cross-reference with the Volvo Penta D3 fuel injector and delivery pipe diagram to verify the cylinders 3-4 position.

Parts Desk Insights

The most common issue with D3 delivery pipe orders is customers ordering by engine family without specifying the cylinder position. All four pipes look similar and are close in price, but they are formed to different routing paths and are not interchangeable. The fastest way to confirm the right pipe is to pull up the D3 fuel injector diagram for the specific engine generation and identify the pipe by its cylinder position. It’s also worth noting that 31251173 supersedes 31303608 — if a customer references the old number, this is the current replacement. Recommend the O-ring kit (31272771) at the same time if any fittings are being disturbed.