| Auto Fuel Delivery System -- Fuel Injection and Carburetor Basics |
From "Weekend Mechanic"
episode WKM-101 |
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Automotive fuel-injection systems can be intimidating for the do-it-yourselfer. But if you start with the right tools, perform the right diagnostic procedures, replace any necessary components and take care of related preventative-maintenance in the process, fuel injection systems are something you can master.
The problem: Our project car, a 1993 Ford Taurus, exhibits hesitation, stalling and has noticeably lost power. The symptoms indicate the problem is with fuel delivery.
DIY Difficulty Rating for Repair: 2 out of a possible 5.
Diagnosing and repairing a fuel delivery system is a substantial weekend project. There are a number of parts involved, and the process is fairly time-consuming. The project should take about a day and a half. We give it a difficulty rating of 2 on a 5-point intermediate-level scale. In a fully equipped shop with professional mechanics and diagnostic computers, the job would take about half a day.
In addition to standard auto-mechanic's tools, some of the specialty tools (figure A) that will be needed for this project include universal spark tester, universal noid light, rpm gauge, and fuel-pressure gauge.
Safety Alert : Fuel-related projects require a well-ventilated work area.
Fuel-Injection and Carburetor Basics
- Traditional basic carburetors (figure B) were functional units, but it was difficult for vehicles to consistently meet government environmental and emissions standards when using them.
- Auto-makers next tried putting electronics on basic carburetors (figure C) to help control their operation. However, when the electronics failed, emissions could be even higher than with earlier standard carburetors.
- The throttle-body design utilized fuel-injectors mounted above the throttle plates of a carburetor chassis (figure D). This design worked fairly well.
- The most efficient fuel delivery system, however, is achieved using a port fuel-injector (figure E). Fuel is introduced into one end of the injector, and the car's computer controls how that fuel passes through into the combustion chamber.
- With a fuel injection engine, the problem exhibited by this vehicle could possibly be related to a malfunction in the on-board computer. Checking a car's computer requires expensive diagnostic equipment or, at least, a trip to a service center. Those options might cost anywhere from $60 to $300. (Some auto centers do, however, rent out diagnostic gear.) The techniques used in this episode follow the more old-fashioned, less expensive approach.
In the segment that follows, a visual inspection is conducted on the engine, followed by three specialized tests that should help pinpoint the exact problem.
RESOURCES :
The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books
Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896
Fuel Injection: Installation, Performance Tuning, Modification
Model: 0879387432
Author: Jeff Hartman
Motorbooks International (MBI Publishing)
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