Mysttoo Common Rail Fuel Injector Block-Off Caps, 5pc Set M12–M20, Carbon Steel Anti-Rust

Mysttoo 5PCS Common Rail Fuel Injector Block-Off Caps are a five-piece steel cap set designed to seal injector ports for pressure diagnostics and to isolate individual cylinders on Cummins, Duramax and Ford Powerstroke engines.

If you need to diagnose faulty injectors, track down engine knock, or temporarily seal the common rail during service, this complete set covers the common thread sizes found on many diesel engines from 2001–2022. Each cap is machined from carbon steel with anti-rust treatment and thread profiles that match OEM fitments, making them a straightforward tool for workshops and DIY mechanics performing fuel system tests and repairs.

Which engines and model years will these caps fit?

The Mysttoo set is engineered to fit modern diesel common rail systems across major platforms: Cummins, Duramax and Ford Powerstroke. Coverage spans model years approximately 2001–2022 depending on configuration, offering broad compatibility for service and diagnostics.

• Covers 2003–2022 Cummins, 2001–2022 Duramax and 2008–2022 Ford Powerstroke applications
• Five thread sizes included: M12x1.5, M14x1.5, M16x1.5, M18x1.5, M20x1.5
• Designed for common rail injector port threads used in diagnostic procedures

How do these block-off caps help with injector testing and troubleshooting?

These caps let you isolate a cylinder by blocking fuel flow to a specific injector, which helps identify a leaking or misfiring injector and narrow down sources of cylinder noise. They’re also useful when conducting pressure checks or performing injector removal without fuel spraying from the rail.

• Seal individual injector ports to stop fuel flow during checks
• Enable step-by-step isolation to locate faulty injectors or knock
• Provide a safer, cleaner way to perform pressure diagnostics on the rail

What are these caps made of and will they resist corrosion and wear?

Each cap is made from carbon steel and receives anti-rust treatment to withstand repeated use in workshop environments. The material and finish help prevent thread wear and stripping when tightening and removing during multiple service cycles.

• High-strength carbon steel construction for durability
• Anti-rust surface treatment to extend service life
• Precision threads to reduce risk of stripping during use

What’s included and what warranty support is provided?

The kit contains five distinct caps sized M12x1.5 through M20x1.5 to address the most common injector thread sizes. Mysttoo supports the product with a 24-month quality guarantee and offers customer support for fitment or usage questions.

• Set of 5 caps: M12x1.5, M14x1.5, M16x1.5, M18x1.5, M20x1.5
• Packaged as a full diagnostic set for workshops and home mechanics
• 24-month quality guarantee and customer support from Mysttoo

Who is this for? The Mysttoo 5PCS Common Rail Fuel Injector Block-Off Caps suit professional diesel technicians, mobile mechanics, and competent DIYers who perform injector diagnostics, rail pressure tests, or cylinder isolation on Cummins, Duramax, and Ford Powerstroke engines. If you need a durable, ready-to-use assortment of thread sizes to stop fuel flow during service and help pinpoint injector faults, this kit gives the practical coverage and corrosion resistance expected in a busy repair environment.