2007.5-2010 GMC Duramax LMM Fuel System Parts

What GM built into the 2007.5-2010 Sierra HD fuel system

Fuel leaves the tank - 26 gallons with a standard box, 34 with the long box - and is pulled forward by the CP3's own gear pump through the frame-mounted filter head, which carries a hand primer and a water-in-fuel sensor. The ACDelco TP3018 element in that head is shared by every 6.6L Duramax built from 2001 to 2016. From there the CP3, tucked into the valley and turned by the cam gear, raises pressure to 26,000 psi and feeds two rails and the six-hole Bosch common-rail injectors. There is no stand-alone fuel-cooled injector driver module on a Sierra of this era; the E35 ECM that arrived with the 2006 LBZ absorbed that job. GM signed the engine off for fuel blends up to B5 biodiesel.

Where these trucks give trouble

Three patterns cover most of the phone calls. First, air on the suction side: the filter housing cracks finely or its seals loosen, the primer splits, and a Sierra that started fine begins cranking long and stumbling - often right after someone changed the filter, since the factory primer is not always up to bleeding the system. Second, low rail pressure, logged as P0087, which can trace to a restricted filter, an air leak, a worn CP3, a failing regulator or tired injectors. A loaded trailer on a hot afternoon is when it shows itself: soft power, a limp on throttle, climbing EGT. Third, plain supply shortfall. With no factory lift pump, the CP3 sometimes has a hard time keeping up, and towing or added fueling turns that into hesitation, sluggish acceleration and low-rail codes. Injector wear is a slower story here than on earlier Duramax engines, but miles do bring rough idle, haze and smoke at start-up, a drop in fuel economy and stubborn cold starts, with no published mileage figure to plan around.

Repair it or improve it

If a code or a power complaint brought you to this page, work in order: fresh filter on schedule, then eyes on the filter-head seals and primer, before anything expensive comes off the truck. Injector diagnosis means balance rates - about -4 to +4 mm3 at idle reads healthy - followed by a return-flow test, with only the proven-bad units replaced. When you want more than stock margin, a frame-mounted lift pump with added filtration is the upgrade that earns its keep on an SLE or SLT that tows: steadier supply under load, less work for the CP3, longer injector life. Hold its output pressure to the CP3 near 10 psi. For trucks built further, stock-flow replacement CP3s, 10, 12 and 14 mm stroker pumps, and factory-flow or modified-flow injectors are all cataloged for the LMM.

What we carry

Supply and filtration: air/fuel separation systems, Raptor pumps, replacement 2 and 10 micron filters, water separators and a low-pressure indicator light from AirDog; Titanium Signature Series systems, filter packs and extended-length water-separator and particulate elements from FASS; the Venom lift pump with filter and separator from BD Diesel; a diesel lift pump, installation kits with 1/2 and 5/8 inch hose, CP3 feed lines, inlet fittings, billet fuel pickup kits, a prewired relay set and a high-capacity filter from PPE; filter-head spacer and adapter kits from XDP; and the ACDelco TP3018. Service and rebuild: filter-head rebuild kits, water-in-fuel sensor O-rings, the injection pump inlet hose and the filter inlet and outlet hoses from Merchant Automotive, plus a filter base and hand-primer seal kit and a fuel transfer pump from Alliant Power. High pressure and chemistry: injectors from Exergy Performance and Dynomite Diesel Products, remanufactured injectors from Alliant Power, hardware from Fleece Performance Engineering, fuel sumps, and additives from Hot Shot's Secret and Lucas Oil.

Fitment notes

Pick tank-related parts by box length, not by badge. The standard-box 26 gallon tank and the long-box 34 gallon tank use different pickups, so sumps and draw straws follow the tank. Sierra HDs of this generation came as a regular cab with the 8-foot box and as extended or crew cabs with a standard or 8-foot box, and the 3500HD came single or dual rear wheel; Work Truck, SLE and SLT trucks share the same fuel hardware. Two model-year lines matter. A 2007 Classic Sierra HD is the previous body with the LBZ, which is why the LMM range begins at 2007.5. And 2011 brought the LML with a CP4 pump and urea injection, so later fuel parts are not backward compatible with your truck. Confirm with the VIN or the RPO sticker in the glovebox, or run the part through the fitment checker.

Frequently asked questions

Does the LMM use a CP3 or a CP4 injection pump?

A CP3. The 2007.5-2010 Sierra HD kept the Bosch CP3 in the engine valley, driven off the cam gear; the CP4 did not arrive until the 2011 LML. That is good news for parts availability, because both stock-flow replacement CP3s and 10, 12 and 14 mm stroker CP3s are cataloged for your engine.

My Sierra goes soft when I tow in the heat. Where do I start?

Start on the fuel supply side rather than at the turbo. Low rail pressure under load is a known pattern on these trucks and reads as reduced power, a limp on acceleration and high EGT, and a restricted filter or an air leak on the suction side is the cheapest cause to rule out. If the truck is loaded often, a frame-mounted lift pump with its own filtration addresses the root issue, which is that the CP3 has nothing helping it draw fuel.

Will fuel parts from a 2011 Sierra 2500HD fit my 2010?

Generally no. For 2011 the LML replaced the CP3 with a CP4 and added urea injection, so the fuel side was reworked. Some service items and filter elements span a wide year range, but pumps, lines and injectors should be ordered specifically for the 2007.5-2010 LMM.

Can I run biodiesel in my Sierra 2500HD?

Blends up to B5 were approved for this engine from the factory; higher blends were not. Whatever you run, keep the filter on schedule and the filter head and primer seals in good shape, because that is where air gets into this system.

Not sure which part matches your Sierra? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.