The Trainer #138: Fuel System Performance Testing Using The Scope (featuring Autel DSO)

There are only four things that can make an engine run badly.

One is a mechanical problem that is preventing the engine from sealing the combustion chamber or pressurizing the air/fuel charge.

The second is an inability to breathe – a problem with volumetric efficiency. 

The third is ignition; that is, the ability of the ignition system to deliver a good, strong spark consistently and at the right time. 

And last, but certainly not least, is fuel. 

Let’s first define what I mean by fuel. This covers everything from the fuel pump to the tip of the injectors and every component related to their proper operation. Critical is the ability of the fuel system to deliver the right quantity of fuel at the right time and in the proper configuration – or spray pattern. And this can be one of the most challenging performance components to narrow down.

But the use of the DSO, or digital storage oscilloscope, can make this task a lot easier. It can also be more efficient and more accurate than many of the traditional testing methods you may be used to. In this edition of "The Trainer," I'll show you how to use the Autel scope module and related accessories to aid you in narrowing down fuel system faults, from a weak fuel pump to a sticking fuel injector. We'll also discuss how the ECM controls this process so you can use that information as your diagnostic pathway. Don't have the Autel scope? No worries - the techniques apply to whatever scope you have at hand.

Let's get started!