TM 10-4610-232-34
Table 2-1. Direct Support Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
DISTRIBUTION PUMP.
1. Distribution pump motor hums but will not turn.
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Check for foreign objects in pump.
Disassemble pump (para. 2-81).
Inspect pump internals for wear and damage.
Replace worn or damaged parts (para. 2-81).
Tag and disconnect motor leads (T1, T2, T3) (REF: Interconnection diagram FO-2, Sheet 10). Set multimeter
to Ohms x 1000 scale and connect test leads between each motor lead and the motor frame. Readings should
be infinity for each step.
Replace motor if the meter reading is zero (para. 2-82).
Set multimeter to Ohms x 1 scale and check for continuity between all pairs of motor leads, T1 and T2, T1 and
T3, T2 and T3. Readings should be zero or near zero for each step.
Replace motor if reading is infinity (para. 2-82).
Turn the motor shaft by hand. It should turn easily, without noise, without dragging, and without rough spots.
If rotation is not smooth, bearings are bad.
Replace motor bearings (para. 2-82).
2. Distrubution pump assembly is noisy.
Step 1. Check for foreign objects in pump.
Disassemble pump (para. 2-81).
Step 2. Inspect pump internals for wear and damage.
Replace worn or damaged parts (para. 2-81).
Step 3. Turn the motor shaft by hand. It should turn easily, without noise, without dragging, and without rough spots.
If rotation is not smooth, bearings are bad. Replace motor bearings (para. 2-82).
3. Distribution pump runs but has low or no flow.
Check pump internals for wear and damage.
Replace worn or damaged parts (para. 2-81).
HIGH PRESSURE PUMP.
1. High pressure pump is noisy. (Also, sea pressure gauge troubleshooting, malfunction 4.)
Isolate noise.
(a) A rumbling noise indicates bad crankshaft bearings. Replace the pump and repair as necessary (para.
2-78).
(b) A knocking noise indicates bad connecting rod bearings. Replace pump and repair as necessary
(para. 2-78).
(c) A clicking or tapping noise indicates valve problems. Check high pressure pump inlet and outlet valve
discs and springs. Replace any valve discs that show radial or circumferential cracks, pitting other
than normal surface wear, nicks, gouges, elongated center holes, and a “chalky” feeling/appearance
when scratched with a fingernail (para. 2-78). Replace any broken valve springs (para. 2-78).
2. High pressure pump motor is noisy.
Turn the motor shaft by hand. It should turn easily, without noise, without dragging, and without rough spots.
If rotation is not smooth, bearings are bad. Replace motor bearings (para. 2-74).
2-10
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