Fuel-Injector Types

The present short article would be the 1st in a series about automotive fuel-injectors. It really is assumed the reader includes a basic understanding of what an injector is and it’s part within the injection system of a vehicle, as well as standard knowledge about fuel-injection technique terminology. Get more information about fuel injector seals

Automotive fuel-injectors appear to become all of the identical but they differ in shape, size and capacity to flow fuel.

Probably the most popular injector will be the top-feed form. You’ll find o-ring injectors which might be typically inserted within a metallic or plastic fuel rail. A different type would be the rubber-hose injector.

Within this variety of injector a rubber hose is directly attached to the injector inlet.


There are generally two kind of side-feed injectors. The very first type of injector is utilised in MPFI (Multi-Port Fuel-Injection) systems. This injector fits inside the fuel rail. The second, is employed in TBI (Throttle-Body Injection) systems and typically fits inside an injector pod. TBI systems are usually confused with electronic carburetors.

This really is not the case. TBI are full-electronic EFI (Electronic Fuel-Injection) systems. They use injectors as opposed to carburetors that depend on pressure differential, venturi, jets, metering rods, energy valves, chokes, floats, and so forth.

TBI EFI makes use of none of those. The only similarity is that fuel is discharged, and travels by way of, the intake manifold.


Direct fuel-injection is really a fuel-injection technologies that enables gasoline engines to use fuel a lot more effectively, resulting in greater energy levels, cleaner emissions, and elevated fuel-economy.

In a popular MPFI program (whether batch or sequential fire) fuel is sprayed towards the intake valve inside the cylinder head ports. This final results in a far more precise fuel-metering compared together with the preceding TBI setup.

Direct Fuel-Injection goes a step additional by placing the injector straight within the combustion chamber, just like a spark-plug. Gone would be the days of 43psi of fuel-pressure considering that a direct fuel-injection system uses pressures as higher as 2500psi. This high fuel pressure is necessary to overcome internal cylinder stress in systems that meters fuel throughout the compression stroke (incredibly related to a diesel engine).

In actual fact this kind of fuel-injection mimics the intake stroke of a Diesel engine thus the 30% benefit in fuel-economy compared to similar displacement gasoline engines.

This sort of injection is referred to as stratified injection, where some amounts of fuel are injected through the compression stroke achieving super lean ratios of 69:1 and an increase in fuel-economy up 30% greater in comparison to a standard sequential-fire fuel-injection program.

Now you realize the fundamental and most typical kind of automotive fuel-injectors. In future articles I’ll speak about injector service and maintenance ranging from fundamental flush to ultrasonic cleaning.

Remain tuned for more about fuel-injectors! Place your comments and happy wrenching!

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