This package includes five (5) Cap/Block-Off Tool
The TamerX Diesel Fuel Injector Cap / Block-Off Tool for 5.9L Dodge/Cummins is a toolbox essential for everyone working on common rail Cummins fuel systems.
When a Cummins common rail engine fails to start, your first troubleshooting step should be to check fuel rail pressure. If the pressure is under 5,000 PSI (on a 5.9L engine), the most likely culprit is a defective diesel fuel injector returning excess fuel back to the tank. A return flow volume test will allow you to determine if excessive fuel return flow is the issue.
To identify the individual cylinder that is at fault, you will use this cap/block-off tool. The diesel fuel injection line is removed from one cylinder at a time and the cap is then installed on the fuel rail in place of each injection line. When the bad injector is blocked off, the fuel pressure at the rail will increase and your engine will start.
In some situations, it can be useful to have multiple block-off tools, because multiple diesel injectors returning a small amount of diesel fuel will display the same symptoms as an individual diesel injector returning an excessive amount of fuel.
The diesel injector cap tool can also be used for diagnosing engine knocking sounds that could possibly be caused by a diesel injector or a single cylinder issue, especially on engines where you can’t use a scan tool or if a scan tool is unavailable.