2007.5-2010 GMC Duramax LMM Fuel Injectors

Injectors on the 2007.5-2010 Sierra 2500HD/3500HD LMM

Fuel on a Sierra HD of this era starts at the tank and is pulled forward by the CP3's own gear pump. There is no factory electric lift pump anywhere in the system. The CP3 is mounted in the valley between the heads and turned by the cam gear, and it sends fuel to two rails at up to 26,000 psi. Each cylinder gets a six-hole Bosch common-rail injector. Injector control is handled inside the ECM on the LMM, since the separate fuel-cooled FICM disappeared when the E35 controller arrived on the LBZ, so a FICM search on one of these trucks comes up empty by design. The factory calibration also accepts B5 biodiesel.

What fails and why

Injector trouble here reads as wear rather than sudden failure. Higher-mileage trucks and trucks fed dirty fuel drift first, and no mileage threshold is published for it. The tells are a rough idle, a haze or puff of smoke at startup, worse economy and a Sierra that cranks longer on a cold morning. Before condemning injectors, rule out supply. Low rail pressure (P0087) comes from a plugged filter, an air leak, a worn CP3 or a faulty regulator just as readily as from worn injectors, and it tends to surface the first hot day you hook up a trailer: reduced power, a limp when you get into the throttle, high EGT. The filter housing itself cracks finely around the seals and at the hand primer, letting air into the supply, which an owner usually experiences as a hard start or a long crank right after changing the filter.

Stock replacement vs. upgrade

Most of the Sierras shopping this page want factory flow back, not more of it. Remanufactured injectors are rebuilt to that spec and are the usual repair; brand-new sets are the choice when you would rather not inherit someone else's core. If the balance-rate problem traces to tired spray ends and the bodies check out, a nozzle set is the smaller job. Modified-flow injectors are cataloged for the LMM as well, but they assume a fuel supply and calibration built around them, so they are a planned project rather than a repair part. Supporting fuel supply matters either way: a frame-mounted lift pump with added filtration steadies delivery under load and takes work off the CP3.

What we carry

Everything listed is LMM injector hardware. Dynomite Diesel Products is the deepest line here, with brand-new and reman sets, stock-flow singles and nozzle sets. BD Diesel and XDP list remanufactured stock-horsepower injectors, and S&S Diesel Motorsport covers the built-fuel-system end. Alliant Power remanufactured injectors appear here too, and a few Alliant listings are cross-year, so read the fitment line on the product before you add it to the cart. Sealing hardware comes from Merchant Automotive (body seal kits, copper seal eight-packs, return line seals) and Mahle. The Duramax hub has the rest of the platform.

Fitment notes

These injectors are for the GMT900 Sierra HD with the LMM. The 2007 Sierra HD Classic is the previous GMT800 body with the LBZ, and it is a different page. 2011 and later Sierra HDs moved to the LML with its CP4 pump and ninth injector, so nothing from that generation interchanges. Work Truck, SLE and SLT trims, 2500HD and 3500HD, single or dual rear wheel all share the same engine-side parts, as do the chassis cab and box-delete trucks. Seal kits are sometimes published across 2004.5-2016 because the washers and seals carried over; injectors do not. Verify by VIN or use the fitment checker.

Frequently asked questions

What do healthy balance rates look like on an LMM?

Roughly minus four to plus four cubic millimeters at idle is the healthy window. One cylinder sitting well outside while the others are tight points at that injector, and a return-flow test confirms it before anything is ordered.

Can I reuse the copper washers?

No. Treat the copper seals, the injector body seal and the fuel return line seals as single-use any time an injector is pulled. Merchant Automotive and Mahle kits on this page cover the set, and the eight-packs match an eight-cylinder job.

Does a lift pump help injectors last longer?

It helps. A frame-mounted lift pump with extra filtration gives the CP3 clean, steady supply and takes strain off it under load, which is the environment injectors live in. Keep the feed pressure modest; owners generally hold it to about ten psi at the CP3.

Are Sierra and Silverado LMM injectors the same part?

Yes. The badge changes, the 6.6L Duramax underneath does not, so an injector cataloged for a 2007.5-2010 Silverado HD fits the matching Sierra HD. Differences between the two are body and trim items, not fuel system. Confirm by VIN if the truck has had engine work.

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.