Description
PAI 645050 is an aftermarket fuel pump check valve for Detroit Diesel Series 50 (8.5L) and Series 60 (11.1L / 12.7L / 14.0L) engines, replacing Detroit OEM 23516993. The valve sits in the fuel return path and holds prime when the engine is shut down, preventing fuel from draining back to the tank and the long-crank no-start that follows. Threaded 3/8 in female × 5/8 in – 18 male, 2.40 in long, 0.87 in hex.
Signs You Need a New Fuel Check Valve
- Hard starting or extended cranking, especially after sitting overnight
- Fuel system loses prime after engine shutdown
- Air in the fuel system causing rough running or stalling
- Fuel filter / Davco bowl level drops after the engine is turned off
- Engine starts fine warm but is reluctant from cold soak
Specifications
| Manufacturer | PAI Industries (USA) |
|---|---|
| Part Number | 645050 |
| Part Type | Fuel Pump Check Valve |
| Engine Compatibility | Detroit Diesel Series 50, Series 60 (11.1L, 12.7L, 14.0L) |
| Inner Diameter | 0.200 in |
| Hex Size | 0.87 in |
| Overall Length | 2.40 in |
| Thread | 3/8 in female × 5/8 in – 18 male |
| Country of Origin | USA |
Cross References
This part replaces or is equivalent to the following part numbers:
- Detroit Diesel: 23516993
- Also known as: A-23516993, A23516993, DDC23516993, 23516919
Applications
This check valve fits the following engines:
- Detroit Diesel Series 50 8.5L (1993–2007)
- Detroit Diesel Series 60 11.1L (1987–1998)
- Detroit Diesel Series 60 12.7L (1987–2007, DDEC I through V)
- Detroit Diesel Series 60 14.0L (2001–2011, DDEC IV through VI)
Representative trucks, buses, and coaches using these engines:
- Freightliner FLD, Classic, Century, Columbia, Coronado, Argosy
- Kenworth W900, T800, T600, T660, T2000
- Peterbilt 377, 378, 379, 385, 386, 387, 389
- Western Star 4900
- Sterling A-Line, L-Line
- MCI, Prevost, Van Hool, New Flyer, Gillig, NABI buses and coaches
- Class A motorhomes (Monaco, Newmar, Country Coach, Newell) on Detroit Series 60 chassis
Verify your engine serial number and the check-valve location on your chassis before ordering — on some Series 60 installations the valve is mounted on the engine, on others it sits in the return line near the fuel tank. Use a fuel-rated thread sealant on installation.
