Fuel Hoses: Ratings, Diameters
and When to Replace Them

What the ratings on a fuel hose mean

A hose listing reads like a short spec sheet. Each line answers a different question about where the hose can go.

As an example, FuelGear's premium diesel delivery hose lists a PVC/NBR inner layer, reinforcement from a harmonic steel wire and polyester yarn, a maximum working pressure of 435 psi, a temperature range of -30 to 80 °C, and suitability for suction and delivery of oils and diesel fuels only.

Match the hose to the fluid first

The inner layer of a hose is made for the fluids it is rated for. Use it with something else and the material can soften, swell, crack or shed particles into the fuel. That is why the fluid line on a listing matters more than any other.

• Diesel and oil. Hose rated for diesel and oils, such as FuelGear's premium delivery hose, is the standard choice for diesel transfer and refuelling.
• Petrol. Petrol needs hose and equipment rated for petrol. A diesel and oil hose is not a substitute. Transferring petrol vs diesel explains why the rest of the setup changes too.
• AdBlue. AdBlue needs hose made from materials that suit it, with no metal in contact that it can attack. See why AdBlue needs dedicated equipment.

Suction hose and delivery hose are not the same job

On the delivery side, the pump pushes fuel out and the hose is under pressure. On the suction side, the pump pulls fuel in and the hose is under vacuum. A hose that is fine under pressure can flatten under vacuum, and a flattened suction line starves the pump.

A suction line that collapses, leaks air or runs too long is one of the most common reasons a pump struggles to draw fuel. Why your diesel pump won't prime works through the suction side in detail.

Choosing the internal diameter

Hose is sized by its internal diameter, the bore the fuel flows through. A narrower bore adds resistance, and the longer the hose, the more that resistance adds up. The result is a pump that delivers less than its rated flow.

• Start at the pump. Match the hose to the pump's inlet and outlet sizes, and do not step down below them without a reason.
• Size for the flow. Higher-flow pumps need a larger bore to deliver what they are rated for. FuelGear's premium hose comes in 3/4 inch, 1 inch and 1 1/4 inch.
• Allow for length. A long run in a small bore costs more flow than a short one. If the hose has to be long, consider the next size up.
• Check the nozzle and meter. The narrowest part of the line sets the real flow, so a large hose into a small nozzle gains little.

Diesel pump flow rates explained covers how hose, fittings and lift reduce the flow a pump actually delivers.

Hose ends and fittings

A hose is only as sound as its ends. The fitting has to suit both the hose bore and the thread on the equipment it connects to.

• Barb to suit the bore. A hose barb is sized to the hose's internal diameter. FuelGear's brass hose barbs come as 3/4 inch barb to 3/4 inch BSP, 3/4 inch barb to 1 inch BSP, and 1 inch barb to 1 inch BSP.
• Thread to suit the equipment. Pump outlets, meters, filters and nozzle inlets each have a thread size and type. Check them before ordering, or allow for an adaptor.
• Secure the hose on the barb. Use a clamp or crimped ferrule suited to the hose and the pressure, and refit it properly after any change.
• Seal the thread for fuel. Use a thread sealant or tape suited to fuel on tapered threads.

Most leaks start at the ends rather than along the hose, so this is the first place to look when a line weeps.

When to replace a fuel hose

There is no single interval that suits every hose. Sun, cold, handling, pressure and the fluid all change how long a hose lasts. Inspect it, and replace it when any of these show.

• Cracks in the cover. Fine surface cracks, especially at bends and near the ends, are the start of a failure.
• Hard or stiff sections. A hose that no longer flexes like the rest of it has aged.
• Soft spots, bulges or swelling. A sign the inner layer or reinforcement has given way, or that the hose has carried a fluid it is not rated for.
• Kinks that stay. A permanent kink restricts flow and weakens the wall.
• Worn through to the reinforcement. If you can see wire or yarn, the cover is no longer doing its job.
• Weeping at a fitting. Re-terminate the end with a fresh cut and fitting, or replace the hose.
• Suction hose that flattens. If the suction line pulls in while the pump runs, the reinforcement has failed.

Making a hose last

• Keep it out of the sun when not in use. UV hardens and cracks the outer cover.
• Don't drag it over sharp edges. Tray edges and concrete wear through the cover quickly.
• Don't drive over it. Crushing damages the reinforcement even when the cover looks fine.
• Coil it loosely, or use a reel. A hose reel keeps the hose off the ground and stops tight bends.
• Don't run the pump against a closed line. Pressure builds with nowhere to go.

Rated for the fluid, sized for the flow

Choose fuel hose by the fluid it is rated for first, then by whether it is built for suction, delivery or both, its working pressure and temperature range, and an internal diameter that suits the pump and the flow. Fit ends that suit both the hose bore and the equipment thread. Inspect it regularly and replace it when it cracks, hardens, swells, kinks, weeps at a fitting or shows its reinforcement.

Frequently asked questions