CLAMP-HOSE 1272836 - Caterpillar

3408 (67U) Industrial 3408 (99U) Marine, 3408 (78Z) Generator Set;
3412 (38S) Industrial, 3412 (7BL, 60M) Marine, 3412 (81Z) Generator Set EnginesField reports indicate that the fuel transfer pump relief valve may be may be opening at a lower than specified pressure. The fuel transfer pump relief valve should open and bypass fuel to keep the fuel pressure at the outlet of the fuel transfer pump at 230 35 kPa (33 5 psi) at full rated load. Indications of low fuel transfer pump outlet pressure include hard starting and low power.
Location of fuel transfer pump components. 7S-4440 Bolt (1). 4B-4863 Washer (2). 6N-1069 Spring (3).If low fuel transfer pump outlet pressure is suspected, install a gauge to measure that fuel pressure. To increase the pressure, 4B-4863 Washers (2) can be installed between bolt (1) and spring (3). See the illustration. Measure the fuel pressure at the outlet of the fuel transfer pump at full rated load each time a washer is installed. Install washers (2) as required to obtain a pressure of 230 35 kPa (33 5 psi).
A 4N-7465 Gasket is required between bolt (1) and the fuel transfer pump housing. Tighten bolt (1) to a torque of 37 4 N m (27 3 lb ft).
Current production engines have two washer added to the fuel transfer pumps. The addition of 4B-4863 Washers is effective with: 3408 (67U17055) Industrial Engine3408 (99U8235) Marine Engine3408 (78Z5349) Generator Set Engine3412 (38S17548) Industrial Engine3412 (7BL53, and 60M5762) Marine Engine3412 (81Z17332) Generator Set Engine
The parts manuals do not currently show this modification.