Fleece Performance 11-16 6.6L LML Duramax Truck PowerFlo In-tank Lift Pump (Long Bed Only)
Running an 8 ft long bed 2011-2016 Silverado or Sierra HD with the 6.6L LML? This Fleece Performance PowerFlo, part FPE-34564, is the long bed version of their in-tank lift pump. It is for the owner who wants to stop asking the CP4.2 to suck fuel the full length of a long wheelbase truck, or who just lost a CP4.2 and refuses to do it twice.
Fleece points out that a factory LML has the CP4.2 pulling fuel from the tank by vacuum. On a long bed truck the tank sits farther back, so the pump pulls through a longer run of line and the filter before it ever builds rail pressure. The CP4.2 depends on diesel for lubrication, and any restriction, air or water on the inlet shows up as wear. With the PowerFlo, two gerotor pump sections inside the tank push fuel forward at a positive pressure. Fleece gives 10-13 psi at idle and rates it to support up to 800 hp. The built-in active fill bucket keeps the pickup supplied when the tank is low or the truck is parked nose up on a ramp.
Pull the fuel filter and inspect it. Metal in the element means the high pressure pump is already damaged and debris has likely reached the rail and injectors. In that case plan on a full repair, like the Industrial Injection LML disaster kit, not just a lift pump. A clean filter plus rail pressure that sags under load is the case this pump solves. Verify your rail pressure sensor reading is believable before blaming the supply. Shudder or harsh shifts on the same truck are a separate problem; our Allison TCC shudder guide covers them.
Listed for 2011-2016 GM Silverado and Sierra 2500HD/3500HD LML pickups with the 8 ft bed. Fleece crosses it to GM 13578389 and 13578388. Note that Fleece shows the same GM numbers for the 6.5 ft short bed pump, FPE-34563, so bed length is how you choose:
Give us your VIN and bed length if you want us to check it. Parts for the Allison behind this engine are on the Allison 1000 page.
Towing heavy with this truck? An Allison 1000 cooler line kit for the LML is cheap insurance, and an Exergy CP4.2 covers a pump that already failed.
| Brand | Fleece Performance |
| Part number | FPE-34564 |
| Fits | Fleece Performance 11-16 6.6L LML Duramax Truck PowerFlo In-tank Lift Pump (Long Bed Only) |
| Type | Fuel Pump Hangers |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. FPE-34564 is built for the 8 ft bed tank. Short bed trucks use FPE-34563.
No. Fleece lists it for single tank pickups only. Cab and chassis owners must check their factory pump number against the Fleece cross-reference first.
Fleece cross-references it to GM 13578389 and 13578388.
No. Metal means the CP4.2 is already failing and debris may be in the rail and injectors. Plan on a full high pressure system repair, then add the lift pump.
No. It uses the factory lines. The ports accept -8 O-ring fittings if you later want custom lines.
Fleece rates it at 10-13 psi at idle.
