technician in the shop

Your fuel system is comprised of a variety of parts, each tasked with keeping your engine running strong - Chevy, Ford, and Ram all have small differences, and diesel systems have changed over the years with innovation in the field; however, the fundamentals haven’t changed. At Harold's Used Auto Parts Inc, our technicians are familiar with the differences between models and generations, but for the intents and purposes here they aren’t necessary to know. Here’s an overview of the major components you’ll find in most diesel fuel systems.

Electronic Fuel Pump - In gas engines, the fuel pump delivers pressurized fuel directly through the fuel lines to the injectors. On diesel engines, the injection pump is responsible for pressurizing the fuel - the fuel pump is only there to pull fuel out of the tank and deliver it to the injection pump.

Injection Pump - Also known as the high-pressure fuel pump, the injection pump is probably the most complex component in a diesel fuel system. The injection pump is powered by the camshaft; inside, there are pistons and a crankshaft, which pressurize the fuel to a level an electric pump isn’t capable of generating. The pistons in the injection pump ramp up the pressure to tens of thousands of PSI.

Fuel Filter/Water Separator - Almost any fuel system will have a fuel filter - but on diesel engines, it’s especially important. Gelled diesel or debris in the fuel will wreak havoc on expensive, intricate components, so it’s essential they are caught before reaching the injection pump. Diesel systems are frequently also equipped with a water separator or water trap - water will damage components that are lubricated by diesel fuel, causing damage in addition to poor running conditions.

Injectors - Injectors deliver the fuel into the cylinder. There are a few types of injectors and injection systems, but they work basically the same way. Injectors withhold pressurized fuel, until fuel pressure, oil pressure, or an electronic charge triggers them to open. They then release a mist of highly compressed fuel into already warmed and compressed air, at the exact moment where combustion is most effective.

Most of these components are complex, and it’s important that they’re maintained by a professional technician. Filter replacements, fuel system flushes, and component repair all factor into keeping these parts in great shape. At Harold's Used Auto Parts Inc, we monitor and diagnose issues and maintenance for the needs of your truck, based on condition, what it is, and how you use it.



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5347 Whitby Ave
        Philadelphia, PA

(215) 472-1552
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MON-FRI | 8:30 AM - 5:30 PM
SAT | 8:30 AM - 2:00 PM
SUN | CLOSED
Closed every third Saturday of the month