When it comes to fuel line sizes vs. fuel supply restriction — also known as pressure drop — there is a lot of misinformation in the marine industry. And it is essential to have a clear understanding of the relationship between fuel line size and fuel pressure if you are planning a fuel delivery system. When pressure loss caused by fuel line size is not taken into account, the fuel system will end up functioning incorrectly.

Does Fuel Line Size Matter?

Fuel line size is an essential factor for marine diesel engines. The diameter and length of the line must be considered to deliver fuel at the correct pressure and rate.

One source of pressure loss is friction. The longer a fuel line is, the more friction there will be. As the flow rate through the line increases, so does the friction. Fuel lines that feed into pressure gauges experience the least amount of pressure loss because the flow of fuel reaches nearly zero.

What Is Fuel Supply Restriction?

Fuel supply restriction refers to a drop in pressure in the fuel line. This pressure drop is measured using a negative number because it is on the suction side of the supply pump or fuel lift. Issues like a clogged filter could cause pressure drop, although it can also be a result of the fuel line size.

What Is the Connection Between Fuel Line Size and Fuel Supply Restriction?

To understand the connection between diesel fuel line sizes and fuel supply restriction, the first thing to consider is the maximum fuel flow to the engine at rated speeds and horsepower output. Next, you’ll need to know the maximum pressure drops that the engine can handle and still work correctly for both the supply and return sides.

On the supply side, fuel lines need to be large because the lines are longer. When the lines are longer, there will be more valves, manifolds, fittings and so on required, so a larger fuel line will result in less fuel supply restriction.

For the fuel return system, the maximum pressure drop is usually two to four times more, and the return flow is less than the total fuel flow. Therefore, fuel lines can be smaller on the return side than the supply side. You can use a larger line on the return side, but it is often more manageable and cost-effective to use smaller lines.

Buy Your Marine Supplies From Diesel Pro Power Today

From fuel lines to transmission components, Diesel Pro Power has the parts selection that will meet all your marine equipment needs. We carry Detroit Diesel engine parts, Cummins engine parts, gauges, cables, filters and much more.

When you buy from Diesel Pro Power, you will receive your parts quickly thanks to our 24-hour shipping and worldwide delivery. You can also order directly from our secure, easy-to-use website. If you have any questions or need help determining which parts you need, contact us today and our customer service specialists will be able to help.

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