Q. My dad is considering the purchase of a new pickup, having finally worn out his ’84. He’s concerned about the fact that all the current trucks have fuel injection, and he’s not familiar with it and can’t work on it. Can you shed some light on the pros and cons of fuel injection compared to his beloved four-barrel carburetor?

Tom Fowler,

San Martin, Calif.

A. I can appreciate your dad’s concern about wanting to be able to work on his new truck. New skills and tools are necessary for many service operations but modern EFI systems require virtually no maintenance and are incredibly reliable.

Let’s take a look at how they work and some of the benefits.

Electronic fuel injection has been around in two forms – throttle body and multiport since the late 1980s. Throttle body systems (one or two centrally located fuel injectors) were the essence of simplicity but are now defunct due to ever-tightening emissions regulations. Multiport fuel injection systems place an individual fuel injector near each cylinder’s intake port, insuring an identical and superbly atomized fuel charge.

EFI systems use a high-pressure electric fuel pump located in or near the fuel tank. A large capacity fuel filter traps contaminants and a fuel pressure regulator maintains the specified pressure during all engine conditions, and except for the latest systems, returns unneeded fuel to the tank.

Fuel injectors are simple yet accurately functioning spray nozzles. When an electrical signal is received, a ball or pintle is lifted, allowing fuel to pass through one or more orifices to the intake manifold. Each injector is pulsed for a few thousandths of a second, once per intake cycle, with the pulse duration varied to match operating conditions.

The system is managed by the PCM (powertrain control module), which receives information from close to a dozen sensors, and executes appropriate commands to the fuel-pump relay, injectors, ignition system, and related engine-management and emission-control devices.

Depending on the vehicle, the PCM also might control the automatic transmission, air conditioning or cruise control. The PCM can detect the slightest circuit or component faults and alerts the driver via the MIL (malfunction indicator-check engine lamp), and records a specific diagnostic trouble code.

EFI systems, compared to a carburetor, offer greater performance, improved fuel economy and reduced exhaust emissions. An EFI system’s electric-electronic components are far more reliable than a carburetor’s many internal and external mechanisms. The few EFI soft spots are the fuel pump and throttle position sensor. Their mechanical components are good for perhaps 100,000 to 150,000 miles. Other than performing the minimal scheduled maintenance, dad should have very little reason to spend much time under the hood.

Brad Bergholdt teaches automotive technology at Evergreen Valley College in San Jose, Calif.

E-mail him at under-the-hoodjuno.com or write to him in care of Drive, Mercury News, 750 Ridder Park Drive, San Jose, Calif. 95190. He cannot make personal replies.)

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AP-NY-06-18-04 0619EDT