P0087 on 2011-2015 GMC Sierra 3500: Low Fuel Pressure Causes & Fixes

What's Unique About the 2011-2015 Gmc SIERRA 3500

This generation of Sierra 3500 presents two very distinct stories for code P0087. For the 6.6L LML Duramax diesel, this code is a notorious warning sign for the failure-prone Bosch CP4.2 high-pressure injection pump. 🎬 Watch: See why the CP4 fails and how a lift pump helps. A CP4 failure can be catastrophic, sending metal debris throughout the entire fuel system and requiring a complete system replacement costing thousands. For the 6.0L gasoline V8, the issue is less severe, with GM issuing Technical Service Bulletins pointing towards fuel system contamination and weak in-tank fuel pumps as primary culprits.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2011-2015 range covers the end of the GMT900 generation (2011-2014) and the beginning of the K2XX generation (2015). Both generations used the 6.6L LML Duramax diesel and the 6.0L L96 gasoline V8. The primary causes for P0087, particularly the CP4 pump issue on the diesel, are consistent across these model years.

Symptoms You May Notice

• Reduced engine power (limp mode)
• Engine is hard to start or will not start
• Check Engine Light is on
• Sluggish acceleration or hesitation
• Engine stalls, especially under load
• Rough or surging idle
• Increased fuel consumption

Most Likely Causes

1. Failing High-Pressure Fuel Pump (CP4.2) (6.6L LML Duramax Diesel) 🔴 High Probability → Shop Fuel Pump The Bosch CP4.2 injection pump used on the 2011-2016 LML Duramax is infamous for catastrophic internal failure due to a lack of lubrication, where it disintegrates and sends metal shavings through the entire fuel system.
   How to confirm: Check the fuel filter housing and the fuel pressure regulator screen for metallic, glitter-like particles. This is the definitive sign of CP4 failure. A cracked pump housing is also a clear indicator.
   Typical fix: This is a catastrophic failure requiring replacement of the high-pressure pump, all fuel injectors, both fuel rails, and all high and low-pressure fuel lines, plus flushing the fuel tank. Many owners opt to proactively replace the CP4 with a more robust CP3 pump via a conversion kit from brands like Fleece Performance or S&S Diesel Motorsport to prevent this failure.
   Est. part cost: $2,000 - $5,000+ for parts alone. A full system replacement at a dealer can cost over $10,000.
2. Clogged Fuel Filter (All Engines) 🔴 High Probability → Shop Fuel Filter Diesel fuel systems are sensitive to contamination, and a clogged filter is the first line of defense. It's a common maintenance item that is often overlooked and a primary cause of low pressure.
   How to confirm: Replace the fuel filter; it's an inexpensive first step. On diesel models, check the fuel filter life monitor on the driver information center. Also, check for excessive vacuum on the low-pressure side. A dirty filter can cause pressure drops under load.
   Typical fix: Replace the fuel filter with a high-quality OEM-spec part (e.g., ACDelco, Racor).
   Est. part cost: $30 - $80
3. Fuel System Contamination (6.0L Gas Engine) 🟡 Medium Probability GM TSBs #16-NA-102 and #PIP5151F specifically call out customer concerns of hard start, no start, and P0087 caused by debris contaminating the fuel system. This can be anything from dirt to foreign objects left in the tank during previous repairs.
   How to confirm: Requires inspection of the fuel system components, including dropping the tank and inspecting the pump and sending unit for foreign debris as outlined in the TSBs.
   Typical fix: Requires cleaning the entire fuel system and replacing contaminated components, which most often includes the in-tank fuel pump module.
   Est. part cost: $250 - $500 for the pump module, plus labor.
4. Failing In-Tank Fuel Pump / Lift Pump (All Engines) 🟡 Medium Probability → Shop Fuel Pump The low-pressure pump in the tank feeds the high-pressure pump (on diesel) or the engine (on gas). If it weakens, it cannot supply enough volume, starving the rest of the system under load. On Duramax trucks, an aftermarket lift pump from brands like FASS or AirDog is a common upgrade for improved filtration and consistent pressure, which can help preserve the life of the high-pressure pump.
   How to confirm: Test the low-pressure fuel system pressure. On gas engines, connect a gauge to the fuel rail. On diesels, check for adequate lift pump pressure (should be around 8 psi) or excessive vacuum at the test port on the filter housing.
   Typical fix: Replace the in-tank fuel pump module. For the 6.0L gas engine, an example part is ACDelco M10266. On diesel trucks, many owners add an aftermarket lift pump.
   Est. part cost: $250 - $700
5. Faulty Fuel Rail Pressure Sensor (All Engines) ⚪ Low Probability → Shop Fuel Pressure Sensor While not as common as pump or filter issues, the sensor that reads the pressure can fail and send incorrect low-pressure signals to the ECM.
   How to confirm: Use a scan tool to compare the 'Desired Fuel Rail Pressure' with the 'Actual Fuel Rail Pressure' reading from the sensor. If the reading is erratic, stuck, or doesn't change with RPM, the sensor is suspect. On a Duramax, idle pressure is around 4,000-5,000 PSI, and can exceed 26,000 PSI under load.
   Typical fix: Replace the fuel rail pressure sensor. On Duramax engines, it is located on the driver's side fuel rail. The OEM part is GM #12651990 or Bosch #0281006313.
   Est. part cost: $80 - $240

Rare But Worth Checking

• Leaking Fuel Injectors (6.6L LML Duramax Diesel): → Shop Fuel Injector An injector can fail internally and return excessive fuel back to the tank instead of spraying it into the cylinder. This bleeds off rail pressure. This is often diagnosed with an injector return rate test, which measures the amount of fuel bypassing the injector.
• Faulty Fuel Pressure Regulator (6.6L LML Duramax Diesel): → Shop Fuel Injection Pressure Regulator The LML Duramax has a regulator on the CP4 pump that meters fuel going in. If it sticks or fails, it can cause pressure issues. However, it's often contaminated by a failing CP4 pump, not the root cause itself.
• Corroded Fuel Pressure Sensor Connector (6.6L LML Duramax Diesel): → Shop Fuel Pressure Sensor GM TSB #20-NA-197 notes that corrosion at the fuel pressure sensor electrical connector can cause a variety of fuel pressure codes, including P0087. A visual inspection of the connector pins is required.
• Collapsed or Kinked Fuel Lines (All Engines): → Shop Fuel Line Older rubber fuel lines can soften with heat and age, causing them to collapse inward under suction from the fuel pump, especially when towing. This restricts flow and triggers P0087. A visual inspection of all fuel lines from the tank to the engine is necessary.

Diagnosis Steps

1. Identify Your Engine: Determine if you have the 6.0L Gas V8 or the 6.6L LML Duramax Diesel, as the diagnostic paths diverge significantly.
2. Check for Other Codes: Scan the ECM for any other stored trouble codes that could provide more clues (e.g., P0191 for a sensor issue, P0088 for erratic pressure).
3. (Diesel) Inspect Fuel Filter for Metal: This is the most critical first step for a Duramax. Remove the fuel filter and pour its contents into a clean container. Swirl the fuel and look for fine, glitter-like metal particles. A magnet can help confirm if the particles are ferrous. If metal is found, the CP4 pump has failed. Do not proceed with other part replacements; the entire system needs replacement.
4. (All) Replace Fuel Filter: If no metal is found (or for gas engines), replace the fuel filter with a new, high-quality part. This is a low-cost step that eliminates a very common cause.
5. Monitor Fuel Pressure with a Scan Tool: Connect a scan tool and observe both 'Desired Fuel Rail Pressure' and 'Actual Fuel Rail Pressure'. At idle, they should be very close. For a Duramax, idle pressure should be around 4-5k PSI. For a 6.0L gas engine, it should be around 50-60 PSI. If the actual pressure cannot keep up with the desired pressure under acceleration, there is a fuel delivery problem.
6. (All) Check Low-Pressure System: Verify the in-tank pump is working. On gas engines, use a mechanical gauge on the fuel rail test port. On diesels, test for 5-8 PSI of lift pump pressure at the filter head test port. A lack of pressure points to a weak in-tank pump or a restriction.

Parts You'll Likely Need

• High-Pressure Fuel Injection Pump (CP4.2) (OEM #12661059) — This is the most common point of catastrophic failure on the 6.6L LML Duramax diesel engine leading to code P0087.
  Trusted brands: Bosch
  OEM price range: $800 - $1200
  Aftermarket price range: $600 - $1000
• Fuel Filter — A clogged fuel filter is a primary cause of fuel restriction and is the first and cheapest part to replace during diagnosis for both gas and diesel engines.
  Trusted brands: ACDelco, Racor, Donaldson
  OEM price range: $50 - $80
  Aftermarket price range: $30 - $60
• In-Tank Fuel Pump Module — On gasoline engines, this is a common failure point. On diesel engines, the factory low-pressure pump can weaken, failing to supply the CP4 pump adequately.
  Trusted brands: ACDelco, Delphi
  OEM price range: $350 - $500
  Aftermarket price range: $200 - $350
• Fuel Rail Pressure Sensor (OEM #12651990) — Can fail and provide inaccurate readings to the ECM, falsely triggering the P0087 code.
  Trusted brands: Bosch, ACDelco
  OEM price range: $150 - $200
  Aftermarket price range: $70 - $120

Related Codes That Often Appear With This One

• P0088 — Fuel Rail/System Pressure - Too High. This can appear with P0087 if the fuel pressure regulator is failing erratically, causing both spikes and drops in pressure.
• P0191 — Fuel Rail Pressure Sensor Circuit Range/Performance. This code points more directly to a problem with the sensor or its circuit, but can accompany P0087 if the pressure is fluctuating wildly.
• P128E — This is a GM-specific code that is often cited alongside P0087 in TSBs #16-NA-102 and #PIP5151F related to fuel contamination on gasoline models.

Technical Service Bulletins (TSBs) & Recalls

• 16-NA-102: Addresses hard start, no start, and P0087 on gas engines due to fuel system contamination.
• PIP5151F: Predecessor to 16-NA-102, also covering fuel system contamination on gas engines with P0087.
• 20-NA-197: Notes that corrosion on the fuel pressure sensor connector can cause P0087 on Duramax models.

Platform-Specific Known Issues

• 6.6L LML Duramax CP4.2 Pump Failure: The most significant issue for this truck. The pump is known to fail, sending metal fragments through the entire fuel system, leading to repairs that can exceed $10,000. The presence of metal shavings in the fuel filter is the tell-tale sign.
• Gasoline Engine Fuel Contamination: TSB #16-NA-102 and #PIP5151F address an issue where debris in the fuel system can cause P0087, hard starting, and no-start conditions. The fix involves a thorough cleaning of the fuel system and replacing affected components.
• Diesel Fuel Filter Head Air Leaks: The housing for the fuel filter on Duramax engines can develop air leaks, especially at the primer button, allowing air to be drawn into the system and causing a loss of fuel pressure.

Mechanic-Grade Diagnostic Values

• 6.6L LML Duramax - Low-Pressure Fuel System Vacuum — expected: 5 to 8 inches of vacuum under full load.. Failure: More than 8 inches of vacuum indicates a restriction (e.g., clogged filter, collapsed line). Less than 2 inches may indicate an air leak into the system.
• 6.6L LML Duramax - High-Pressure Rail Pressure (Scan Tool) — expected: Desired vs. Actual should be nearly identical. Idle: ~4,000-6,000 PSI. Wide Open Throttle (WOT): ~26,000 PSI.. Failure: If Actual pressure is more than 2,000 PSI below Desired pressure under load, it signifies a high-pressure side issue (pump, injectors, regulator).
• 6.6L LML Duramax - Fuel Rail Pressure Sensor Voltage (KOEO) — expected: Approximately 1.5V to 1.8V with Key On, Engine Off.. Failure: Readings outside this range can indicate a faulty sensor or wiring issue.
• 6.0L Gas - Fuel Pressure (Mechanical Gauge) — expected: 50-60 PSI at the fuel rail test port.. Failure: Pressure below this range indicates a weak in-tank pump, clogged filter, or restriction.

Scan Tool Commands That Help

• GDS2 / Tech2 or equivalent professional scanner: Command Max Rail Pressure at Idle — For 6.6L Duramax, this test helps determine the health of the high-pressure pump (CP4). If the pump cannot achieve maximum commanded pressure while at idle, it is likely failing.
• GDS2 / Tech2 or equivalent professional scanner: Fuel Injector Return Flow Test — For 6.6L Duramax, this command, used with physical measurement tools, helps identify leaking injectors that are bleeding off rail pressure. The scan tool controls the engine while the technician measures the physical return volume from each injector.
• GDS2 / Tech2 or equivalent professional scanner: Fuel Pump On/Off Command — For all engines, this allows a technician to activate the in-tank fuel pump without the engine running, which is useful for testing pump operation and checking for leaks in the low-pressure system.

Wiring & Ground Locations

• Fuel Pump Relay (Gas Engine) — In the main engine fuse box on the driver's side of the engine compartment.. A faulty relay can prevent the in-tank fuel pump from activating, leading to a no-start and P0087. Some models may not have a discrete relay and use a Fuel Pump Control Module instead.
• G300 / G305 (Grounds) — G300 is located below the driver's door on a body mount. G305 is under the vehicle to the rear of the left B-pillar at the third body mount on the frame.. These are chassis grounds. The fuel pump and its control module rely on a solid ground connection. Corrosion or looseness at these points can cause intermittent low voltage to the pump, reducing its output and triggering P0087.
• Fuel Rail Pressure Sensor Connector (LML Duramax) — On the driver's side fuel rail, near the firewall.. TSB #20-NA-197 specifically identifies corrosion within this connector as a cause for P0087. The pigtail wiring order is reportedly Blue/Black, Black/Blue, Yellow.

Real Owner Repair Stories

• Race Ready Fab on YouTube (2010 Duramax LMM (similar architecture to LML)) — Intermittent P0087 low rail pressure code, truck would die in the parking lot.
  ❌ Tried (didn't work) Replaced fuel filter with an AC Delco part., Replaced fuel filter again with a Wix filter., Installed a rail pressure relief valve plug.
  ✅ What actually fixed it Upon dropping the fuel tank to install a lift pump, the technician found debris inside the tank blocking the suction line. A previous technician had left the paper installation manual for the sending unit inside the tank, which was getting sucked up and restricting fuel flow.
• Reddit user r/Duramax (LMM Duramax with P0087) — P0087 code would return regularly, especially under load with a tune.
  ❌ Tried (didn't work) Adding a lift pump (only temporarily helped).
  ✅ What actually fixed it The final fix was replacing the CP3 high-pressure pump and all fuel injectors. The injectors were found to be returning too much fuel. The user also noted that soft fuel lines near the transmission had collapsed/kinked with age, which is a known issue contributing to fuel restriction.

OEM Part Supersession History

• 12611873 → 12651990 — Standard part revision and consolidation by GM.
  Heads up: Part number 12651990 is the current correct OEM replacement fuel rail pressure sensor for the 2011-2016 LML Duramax engine.