Fuel Pump - TM-10-3930-634-340060

TM 10-3930-634-34

resting on the ends of exhaust valve when

t i g h t e n i n g rocker shaft bracket bolts. Note

position of exhaust valve bridge before,

during, and after tightening the rocker shaft

bracket bolts.

(d) Move rocker arm assembly into position and

t i g h t e n rocker arm bracket bolts to 50-55 lb-ft. of

torque.

CAUTION

Do not bend fuel pipes and do not exceed

specified torque. Excessive torque will twist

or fracture flared end of fuel line and result

in leaks. Lubricating oil diluted by fuel oil can

cause serious damage to engine bearings.

(e) Tighten the fuel pipe connections to 12-15

lb-ft. of torque.

(f) Adjust the exhaust valves (para 3-12, b).

(g) Time the fuel injectors (para 3-12, c).

(h) Install the rocker arm cover (para 3-16).

i. Checking Spray Tip Concentricity.

(1) Place the injector in the concentricity gage as

illustrated in figure 3-51 and adjust the dial indicator

to zero.

(2) Rotate the injector 360 and note the total

runout as indicated on the dial.

(3) If the total runout exceeds 0.008 inch, remove

the injector from the gage. Loosen the injector nut, re-

center the spray tip, tighten the nut to 75-80 lb ft.

torque and recheck the concentricity.

(4) If after several attempts, the spray tip cannot

be positioned satisfactorily, check the reassembly of

(b) Connect a flexible tube to the fuel return line

the entire injector.

as illustrated in figure 3-53.

3-19. Fuel Pump

(c) Start and run engine at approximately 1200

RPM.

a. General The fuel pump is a positive displacement

(d) Collect the fuel from the return line for a pe-

gear type which transfers the fuel from the supply

riod of one minute.

tank to the fuel injectors. The pump circulates an ex-

(e) Stop the engine and measure the fuel col-

cess supply of fuel through the injectors which purges

lected. The volume of fuel collected must be not less

the air from the system and cools the injectors. The un-

than 1/2 gallon.

used portion of fuel returns to the fuel tank by means

(f) If fuel flow is insufficient for satisfactory

of a fuel manifold and return line.

engine performance, clean or replace fuel strainer.

b. Testing.

(g) If fuel flow is still insufficient, replace sec-

(1) Fuel Pressure Test.

ondary fuel filter and recheck fuel flow. If fuel flow is

(a) Remove rocker arm cover (para 3-16).

unsatisfactory, replace fuel pump.

(b) Connect a pressure gage as illustrated in fig-

(h) Remove flexible hose and reconnect return

ure 3-52.

line to fuel supply tank.

(c) Start and run engine at 2500 RPM.

c. Removal.

(d) Observe fuel pressure on pressure gage. The

(1) Remove the fuel pump (TM 10-3930-634-12).

pressure must be not less than 35 psi. Nominal fuel

(2) Cap fuel lines.

pressure at 2500 RPM is 45-70 psi.

d. Disassembly.

(e) If pressure is below 35 psi repair the fuel sys-

(1) Disassemble the fuel pump in numerical se-

tem.

quence as shown in figure 3-54.

(f) Remove gage, replace fuel pipe and install

(2) Remove seals (13 and 14, fig. 3-54) as shown

rocker arm cover.

in figure 3-55.

(2) Fuel Flow Test.

e. Cleaning. Clean all parts with cleaning solvent

(a) Disconnect the fuel return line from the fuel

P-D-680 and blow dry with compressed air.

supply tank.

3-32