Figure 3-90. Main throttle shaft shim check.

*TM 9-2815-213-34

line connections between tank and

pump for tightness. Check for proper

mating of gear pump to pump housing.

Insure that fuel supply tank is full.

(2) Adjust Vacuum.

(a) Open test stand flow control valve

completely.

(b) Increase pump speed to 100 rpm below

engine rated speed of 3000 rpm.

line to obtain 8 on vacuum gage (fig. 3-80).

(3) Set Pump Flow.

(a) Set pump speed to 3000 rpm.

(b) Close flow control valve (fig. 3-80) until

flow meter registers 540 p.p.h.

the flow meter.

Figure 3-90. Main throttle shaft shim check.

NOTE

Disregard change in vacuum meter

g. Calibration Procedure (Flow Meter Method:

readings.

CAUTION

(4) Set Ground Speed.

Test stand motor switch is marked "RE-

(a) With throttle wide open, increase pump

VERSE" and "FORWARD." For all

speed to point where fuel pressure just begins to

testing of this pump the stand switch

decrease (peak point). This should occur at speed of

must be set to the "FORWARD"

3020 to 3040 rpm. Check speed twice as fuel pump

position.

This corresponds to the

tachometer drive is turning at /2 engine speed.

rotation requirements of "L" on the pump

(b) If peak point speed is lower than

name- plate (fig.

3-84).

Refer to

specified, add shims (fig. 3-92) between governor

paragraph 3-104.d. (1).

spring and retainer. To reduce speed, remove shims.

Each 0.001 inch shim thickness will change speed

(1) Check Pump Seals.

approximately 2 rpm.

(a) With test stand operating at 5C rpm

(5) Set Throttle Leakage.

(throttle wide open) close control valve in fuel pump

(a) Insure that flow-meter reading is 540

suction line till vacuum gage reads 1 inches vacuum.

The fuel flow control or need valve should be open

during this check.

(b) Put a small amount of Lubriplate ( light

cup grease over the vent or "weep" hole main shaft seal

bore of fuel pump front cover (fig. 3-91).

the 15-inch vacuum setting, it is an indicate that the seal

will not permit proper fuel pun performance and should

be replaced.

(d) Perform the above check on the throttle

shaft to check the shaft O-Ring. App lubricant at the

throttle.

(e) Remove tachometer cap and fill the

tachometer seal bore with test fuel from the stand. If the

fuel is drawn into the pump, r place the seal.

Figure 3-91. Weep hole leakage.

NOTE

During the above checks observe the

flow meter for the presence of air

bubbles. Air bubbles are an indication of

air leakage into the system. Check the

3-49