EVIL ENERGY M20*1.5 Diesel Fuel Rail Plug For 2007.5-2012 6.7L Dodge Cummins & 2004.5-10 GM 6.6L Duramax

Diagnosing the Problem

Q: My 2010 Ram 2500 6.7L Cummins sets P0087 under heavy throttle. Will the EVIL ENERGY fuel rail plug fix it?

A: Only if the relief valve is the cause. P0087 means actual rail pressure fell below what the ECM commanded. That can come from a weak PRV, but also from clogged fuel filters, low lift pump pressure, a worn injection pump or a failing pressure sensor. If the filters are fresh, supply pressure is healthy and the code appears only at high load, a PRV opening early is the likely cause, and the plug addresses exactly that.

Q: What does P1093 mean on a 6.6L Duramax, and when does a fuel rail plug help?

A: P1093 is low fuel rail pressure during power enrichment, meaning the ECM asked for more pressure under load and didn’t get it. On LLY, LBZ and LMM trucks with a tune or bigger injectors, a relief valve that cracks open early is a known cause. A fuel rail plug stops that bleed-off. It won’t fix a weak lift pump or a tired CP3.

Q: Can a leaking relief valve cause hard starts on a 6.7L Cummins?

A: Yes. The rail has to build pressure before the injectors fire, and a valve that seeps fuel back to the tank slows that down, which means longer cranking. Blocking the port with a fuel rail plug lets pressure build faster on cold and hot starts.

Before You Buy

Q: Does the EVIL ENERGY fuel rail plug fit a 2013–2018 Ram 6.7L Cummins?

A: The EVIL ENERGY plug is listed for 2007.5–2012 6.7L Cummins. Some aftermarket rail plugs are sold for later model years too, so the port may be shared. Before ordering for a 2013+ truck, confirm that your relief valve uses the same M20 × 1.5 thread. If you’re unsure, contact support with your VIN.

Q: Will the fuel rail plug fit an LB7 Duramax?

A: No. The fitment covers 2004.5–2010 6.6L Duramax only (LLY, LBZ and LMM). The 2001–2004 LB7 is not listed.

Q: Do I need a custom tune to run a fuel rail plug?

A: Not to install it. The ECM still controls rail pressure through the pump’s metering valve. The plug only removes the mechanical relief path. That said, most trucks that need a plug already run a tune or upgraded injectors, because that is when the factory valve starts to open too early.

Q: Is a fuel rail plug legal on a street-driven diesel truck?

A: The plug doesn’t remove or alter any emissions component. It does replace a factory safety relief valve, and several brands sell rail plugs for off-road or competition use. Check your state’s inspection rules before installing one on a truck that gets inspected.

Installing It

Q: Do I really have to remove the intake manifold to install the fuel rail plug on a 6.7L Cummins?

A: In practice, yes. The two options are removing the EGR and intake manifold, or removing the fuel rail itself. The intake route is faster, and it avoids disturbing the hard-to-reach line fittings at cylinders #5 and #6.

Q: What torque does the fuel rail plug need, and should I reuse the O-ring?

A: Torque it to 72 ft-lbs on both the 6.7L Cummins and the 6.6L Duramax, using a torque wrench rather than guessing. Lubricate the O-ring with clean diesel fuel or engine oil. Reuse the original O-ring only if it’s undamaged and still flexible; otherwise use the O-ring included with the plug.

Q: How do I keep dirt out of the injectors while the rail is open?

A: Clean around the valve before loosening it, and cap every open line and port right away. Never wipe the sealing faces with a shop rag that sheds lint. Common rail injectors have extremely tight tolerances, and a single grain of grit can damage a nozzle.

After the Install

Q: What should I check after the first drive with the fuel rail plug installed?

A: Look for any wetness around the plug with the engine running, then again after the drive. With a scan tool, compare desired and actual rail pressure under load. They should now track closely at full throttle, where they used to split apart.

Q: With the relief valve gone, what protects the rail if pressure spikes too high?

A: Nothing mechanical; the ECM’s pressure control is the only safeguard. If you ever see P0088 (fuel rail pressure too high) or rough running, stop driving and diagnose the pressure sensor and metering valve before going further. Keep the stock relief valve in a clean bag in case you need to reinstall it for troubleshooting.