Heavy Duty Reliability
Building engines isn’t easy; engine regulations change quickly, and demand for specific engine types also varies. When it comes to engines used for bigger and more robust vehicles, specs are often more predictable, with the most important aspect being reliability and dependability.
You’d be surprised to know that medium-duty vehicles like buses, fire trucks, dump trucks, and even RVs use a specific engine from one builder. Cummins is known as the diesel king, having specialized in developing and powering multiple heavy-duty vehicles with Cummins diesel engines. Most of these engines are known to be bulletproof, but a recently announced recall shows that sometimes you can’t control the quality of everything.
Cummins/YouTube
Faulty Fuel Hose
The National Highway Traffic Safety Administration (NHTSA) issued a safety recall report No.26E066. It details an issue with the Cummins L9 in-line 6 diesel engine. The recall is specific to the remote fuel filter hoses (part numbers: FF90942/91044 PN6316754, FF90943 PN6316757, FF90944 PN6316899) that may be loose and detach, creating fuel leaks. This problem is a concern because any leak or breach in the fuel hose can deprive the engine of a proper, sufficient fuel supply.
Furthermore, the NHTSA recall states that the L9 diesel fuel hose might not only cause a stalled engine (due to a lack of fuel supply) but could also cause a crash or, worse, a fire if leaked fuel comes into contact with an ignition source. According to the recall report, the loose-fitting hose may be caused by “insufficient crimping of the connector, possibly resulting in insufficient hose retention.” You may notice the issue by a fuel smell or visual cues, or by an engine malfunction indicator lamp.
Tiffin
The Affected
NHTSA’s safety recall report lists the affected engines as being built from Dec 07, 2020 – Apr 10, 2026, with a total of 39,052 affected engines. As mentioned, there are multiple applications for the L9 engine, but the recall report does list certain manufacturers that have possibly bought the affected engines: Big Rig, Battle Motors, Grove Worldwide, Temsa, Tiffin Motorhomes, Shyft Group, Suthpen Corporation, Nova Bus, Autoacar LLC, New Flyer Industries LTD, Gilig Corporation, DTNA, PACCAR.
The fix is relatively simple, as explained in the recall report: replace the faulty hose with a better, more robust one.
Stellantis
