Piaggio 850509 Diesel Fuel Pump – Porter 1400 Diesel Pick-up and Van (1998-2005)

The Piaggio 850509 diesel fuel pump is the mechanical AC pump that transfers diesel fuel from the tank to the injection pump on the Piaggio Porter 1400 Diesel, in the Pick and Van versions produced from 1998 to 2005. It is not electric: it is mechanically operated by the engine and has a manual priming lever to fill the circuit after a filter change or storage. The supply also includes the sealing O-ring. Code 850509, new original spare part.

✓ Strengths

• Original Piaggio spare part – not a reconditioned equivalent: many compatible pumps are on the market, this is the one with the manufacturer's code.
• Sealing O-ring included – the package includes the sealing ring, verified on the part in stock: many equivalents need to be fitted by reusing the old one or buying the gasket separately.
• Manual priming lever – allows you to fill the circuit without having to crank the starter motor for a long time after replacing the diesel filter (observed from the product photograph).
• Light alloy body – silver-coloured casting with membrane dome and two-hole fixing flange (observed from the photograph).
• Typical maintenance part – on older Diesel Porters, the AC pump is among the most common causes of difficult starting and loss of power.

Technical features

* alternative code format used by some retailers.
** data observed from the product photograph, not declared in the catalogue.
*** indicative value: weight is not declared in the catalogue. One retailer indicates 0.380 kg for the equivalent pump.

Vehicle compatibility

Do you have a Porter from a different year or trim and are unsure? Contact us for more information: with the chassis number, we can verify the exact code for your vehicle before you order.

Who it's perfect for

It's the right spare part for anyone who has a Diesel Porter that starts with difficulty, loses power uphill, or stalls under load and has already ruled out filter and hoses. It's for workshops working on light commercial vehicles and small tradespeople who use their Porter every day for work and cannot afford for it to be out of service: fitting the original part instead of a compatible pump means not having to revisit it after a few months.

Frequently asked questions

How do I know if my Porter's fuel pump needs replacing?
Typical symptoms include long or difficult starting, especially when cold, loss of power under load, sudden stalling, and the need to prime by hand frequently. Before replacing it, it's advisable to rule out a clogged diesel filter, cracked hoses that draw air, and a dirty pre-filter, which produce very similar symptoms.

Is this pump original Piaggio or an equivalent?
It is the original Piaggio spare part with code 850509, also reported by some retailers as 655.850509. Many compatible pumps with the same reference are available on the market – RMS, BCD 2707/2, Meat & Doria, Hoffer – which cost less but are not the manufacturer's part.

Is the O-ring included in the supply?
Yes. The package includes the pump and its sealing O-ring, which we have verified directly on the part in stock. This is a significant difference compared to several equivalents, which arrive without a gasket and force you to reuse the old one or order it separately.

Do I need to bleed the system after installing it?
Yes. After replacing the pump, the circuit contains air: use the manual priming lever to fill it until the diesel fuel runs clean, then start the engine and check for leaks from the mounting flange and connections. For any doubts about installation, contact us for more information.