CHEVYTHUNDER.COM
TROUBLESHOOTING
Before you can go into troubleshooting, you'll need some important tools to help you. Without them, it will be difficult, if not impossible to diagnosis and repair fuel injection problem. The most important tools to use beside s your eyes are the fuel pressure gauge, digital voltmeter, and hand vacuum pump. There are other tools, and I'll explain them as we go along.
The first picture shows a fuel pressure gauge, with a bleeder valve line. if you are going to do troubleshooting, this tool is a definite must. A lot of problems associated with performance are fuel pressure related .
Warning!!!!!: Do not use a regular fuel pressure tester that is only rated for 15 psi! TPI fuel injection pressures can be as high as 50psi, buy a fuel pressure gauge that is rated for at least this high, most go up to 100psi rating.
The second picture shows a digital volt-ohmmeter (DVM). This tool is also a definite must have. You can spend anywhere from $20-100, the higher end models, usually have features that are not required but might be nice to have, such as temperature probe and frequency counter. The DVM is the only meter to use on troubleshooting electrical problems on tpi systems. The reason is that the digital meter has a very high sensitivity or impedance to current, usually around 10 megohms per volt, as compared to a analog (needle) meter which is around 20K ohms per volt. This means that the higher impedance has a extremely small effect on the reading, and when you are dealing in small voltage variations of one hundredth volt (.01V) down to a millivolt (.001V), this is very important. A analog meter internal impedance is so low, in fact, that it will give you false readings, which will hamper your ability to interpret problems. Also the current draw through the analogs internal power supply will damage sensitive components, such as O2 sensors.
The next picture above shows to "low tech" tools that are still extremely useful in troubleshooting. The first one to left in the picture is a 12V test light. Useful for probing wires to check for power, and to see if certain devices are getting power. The second item in the first picture is a continuity tester. Basically it is used to see if you have a broken or open circuit between to connections or terminals. This particular one is a 3V tester, and you can make one from a small cheap flashlight. Just be sure not to touch a hot wire with it or you will burn out the bulb in a flash! The second picture above is a inductive timing light. A good one will set you back around $50 or so, but well worth the money spent. The inductive type means it has a clamp on "probe" that clamps around the wire, and the induced current through the spark plug wire activates the timing light. These are the best, the others that require you to back probe your spark plug boot or remove it to add an adapter to use can be dangerous, as you will be exposed to the potential of a possibly lethal shock.
