2007.5-2010 Chevy Duramax LMM Fuel System Parts

How the fuel system works on the 2007.5-2010 LMM Duramax

The Bosch CP3 sits in the valley between the cylinder heads and is driven off the cam gear. It does two jobs: it pulls fuel from the tank, and it pressurizes that fuel to 26,000 psi for the two rails and the six-hole Bosch common-rail injectors. On the way up, fuel passes through the frame-mounted filter head with its hand primer and water-in-fuel sensor, and the factory element there is the ACDelco TP3018 that every 6.6L Duramax from 2001 to 2016 shares. Tank size follows the box: 26 gallons behind a standard box, 34 gallons behind the 8-foot box. Injector control lives in the ECM on this truck - the separate fuel-cooled injector driver module went away when the E35 controller arrived with the 2006 LBZ. Blends up to B5 biodiesel were approved from the factory.

What fails and why

Low rail pressure is the complaint we see most. A P0087 can come from a plugged filter, an air leak on the suction side, a tired CP3, a bad pressure regulator or worn injectors, and it usually shows itself first towing in summer heat: reduced power, a limp on acceleration, high EGT. The filter housing is a known weak spot in its own right. Micro-cracks and loose seals let air seep into the supply, and the primer can crack, which is why a truck that ran fine yesterday hard-starts, stumbles and cranks a long time right after a filter change - and why the factory primer is often not enough to bleed it back out. Because nothing feeds the CP3 but the CP3, supply can simply fall behind under load; owners who tow or who have added fueling report hesitation, sluggish acceleration and low-rail codes. Injectors wear too, far less dramatically than on the earlier LB7, and the signs are rough idle, haze and smoke on start-up, a drop in economy and harder cold starts. No manufacturer threshold is published for when that happens.

Stock replacement vs. upgrade

Start with the cheap, correct steps. Change the filter on schedule and inspect the filter-head seals and the primer before you start replacing pumps over a rail-pressure code. If injectors are suspect, read balance rates first - roughly -4 to +4 mm3 at idle is considered healthy - then confirm with a return-flow test, and replace only the ones that prove faulty rather than all eight on suspicion. On the upgrade side, the single most useful addition to an LMM is a frame-mounted lift pump with extra filtration: it steadies supply under load and takes work off the CP3, which extends pump and injector life. Keep the pressure it delivers to the CP3 modest; the long-standing rule of thumb is no more than about 10 psi. Past that, OEM-flow replacement CP3s, 10, 12 and 14 mm stroker CP3s, and both factory-flow and modified-flow injectors are cataloged for this engine.

What we carry

This page gathers the supply side, the filtration side and the high-pressure side in one place. Merchant Automotive covers the service parts: filter-head rebuild kits from a basic seal set up to a master kit, water-in-fuel sensor O-rings, the injection pump inlet hose, and the inlet and outlet hoses at the filter. PPE brings its diesel lift pump, lift-pump installation kits with 1/2 and 5/8 inch hose, CP3 feed-line kits in 3/8 and 1/2 inch with and without fittings, CP3 inlet fittings, billet aluminum fuel pickup kits, a ported fuel rail fitting, a rail-pressure gauge harness and a high-capacity filter. AirDog and FASS supply complete air/fuel separation systems along with their replacement 2 and 10 micron elements, water separators, particulate filters and Raptor pumps, and BD Diesel has the Venom lift pump with filter and separator. For the high-pressure end there are injectors from Exergy Performance and Dynomite Diesel Products, remanufactured injectors, a fuel transfer pump and a filter base and hand-primer seal kit from Alliant Power, hardware from Fleece Performance Engineering, filter-head spacer and adapter kits from XDP, the ACDelco TP3018 element, fuel sumps, and fuel additives from Hot Shot's Secret and Lucas Oil.

Fitment notes

Box length drives the fuel tank, and the tank drives the hardware: the 26 gallon standard-box tank and the 34 gallon long-box tank use different pickups, so sump and draw-straw kits are chosen by tank, not by trim. Work Truck, LT and LTZ Silverados all share the same fuel system. Two dates matter more than any badge. The LMM only came in the new GMT900 body, which is why this range starts at 2007.5 - a 2007 Classic Silverado HD is the older body with the LBZ behind it, and not every part listed here will match it. At the other end, the 2011 LML dropped the CP3 for a CP4 and added urea injection, so 2011-and-up fuel parts do not cross back to your truck. Regular cabs came with the 8-foot box, extended and crew cabs with a standard or 8-foot box, and the 3500HD came single or dual rear wheel. Check your VIN or the RPO sticker, or use the fitment checker on the product page, before you order.

Frequently asked questions

Does a 2007.5-2010 Silverado 2500HD need a lift pump?

It does not need one to run. GM never fitted an electric lift pump to the 2001-2016 Duramax, and the mechanical pump at the rear of the CP3 does the lifting. It is still the most common addition on these trucks, because a frame-mounted pump with its own filtration steadies supply under load and takes work off the CP3. If you add one, keep delivery pressure to the CP3 modest - about 10 psi is the accepted ceiling.

What fuel filter does the LMM take?

The factory element is the ACDelco TP3018, the same filter used across the 2001-2016 6.6L Duramax engines. A fresh filter on the manufacturer's schedule is the first move when rail pressure or power is off, and it is a lot cheaper than chasing the code with parts. While you are under there, look closely at the filter-head seals and the hand primer.

My truck hard-starts and cranks a long time after a fuel filter change. What is that?

Air in the supply side, most likely. The filter housing is known for micro-cracks and loosening seals, the primer itself can crack, and the factory primer is often not strong enough to bleed the system properly afterward. Rebuild kits for the filter head and fresh seals exist for exactly this complaint, and replacing the hoses in and out of the filter at the same time is cheap insurance.

How can I tell whether my LMM injectors are worn?

Read balance rates on a scan tool first; roughly -4 to +4 mm3 at idle is considered healthy. Confirm with a return-flow test, then replace only the injectors that prove faulty. Rough idle, haze or smoke on start-up, falling economy and harder cold starts are the symptoms that usually send owners looking, and there is no published mileage at which it happens.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.